記述言語：英語   掲載種別：研究論文（学術雑誌）  

Pseudomonas syringae pv. tabaci 6605 (Pta6605) is a foliar plant pathogen that causes wildfire disease on tobacco plants. It requires chemotaxis to enter plants and establish infection. While chemotactic signals appear to be the main mechanism by which Pta6605 performs directional movement, the involvement of aerotaxis or energy taxis by this foliar pathogen is currently unknown. Based on domain structures and similarity with more than 50 previously identified putative methyl-accepting chemotaxis proteins (MCPs), the genome of Pta6605 encodes three potential aerotaxis transducers. We identified AerA as the main aerotaxis transducer and found that it possesses a taxis-to-serine-and-repellent (Tsr)-like domain structure that supports a periplasmic 4HB-type ligand-binding domain (LBD). The secondary aerotaxis transducer, AerB, possesses a cytosolic PAS-type LBD, similar to the Aer of Escherichia coli and Pseudomonas aeruginosa. Aerotaxis ability by single and double mutant strains of aerA and aerB was weaker than that by wild-type Pta6605. On the other hand, another cytosolic PAS-type LBD containing MCP did not make a major contribution to Pta6605 aerotaxis in our assay system. Furthermore, mutations in aerotaxis transducer genes did not affect surface motility or chemotactic attraction to yeast extract. Single and double mutant strains of aerA and aerB showed less colonization in the early stage of host plant infection and lower biofilm production than wild-type Pta6605. These results demonstrate the presence of aerotaxis transducers and their contribution to host plant infection by Pta6605.

DOI： 10.1264/jsme2.ME21076

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

担当区分：最終著者,　責任著者   掲載種別：研究論文（学術雑誌）  

DOI： 10.5423/ppj.oa.06.2021.0087

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その他リンク： http://ppjonline.org/journal/view.php?doi=10.5423/PPJ.OA.06.2021.0087

担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Elsevier BV  

DOI： 10.1016/j.micres.2021.126869

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： https://doi.org/10.1016/j.micres.2021.126869

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER SOC MICROBIOLOGY  

Pseudomonas amygdali pv. tabaci strain 6605 is the bacterial pathogen causing tobacco wildfire disease that has been used as a model for elucidating virulence mechanisms. Here, we present the complete genome sequence of P. amygdali pv. tabaci 6605 as a circular chromosome from reads using a PacBio sequencer.

DOI： 10.1128/MRA.00405-21

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担当区分：最終著者,　責任著者   掲載種別：研究論文（学術雑誌）   出版者・発行元：Elsevier BV  

DOI： 10.1016/j.bbrep.2021.100944

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担当区分：最終著者,　責任著者   掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer Science and Business Media LLC  

DOI： 10.1007/s00438-020-01745-y

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その他リンク： http://link.springer.com/article/10.1007/s00438-020-01745-y/fulltext.html

担当区分：最終著者,　責任著者   掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer Science and Business Media LLC  

DOI： 10.1007/s10327-020-00961-z

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その他リンク： http://link.springer.com/article/10.1007/s10327-020-00961-z/fulltext.html

担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：KOREAN SOC PLANT PATHOLOGY  

Pseudomonas syringae pv. tabaci 6605 has two multidrug resistance (MDR) efflux pump transporters, MexAB-OprM and MexEF-OprN. To understand the role of these MDR efflux pumps in virulence, we generated deletion mutants, Delta mexB, Delta mexF, and Delta mexB Delta mexF, and investigated their sensitivity to plant-derived antimicrobial compounds, antibiotics, and virulence. Growth inhibition assays with KB soft agar plate showed that growth of the wild-type (WT) was inhibited by 5 mu l of 1 M catechol and 1 M coumarin but not by other plant-derived potential antimicrobial compounds tested including phytoalexins. The sensitivity to these compounds tended to increase in Delta mexB and Delta mexB Delta mexF mutants. The Delta mexB Delta mexF mutant was also sensitive to 2 M acetovanillone. The mexAB-oprM was constitutively expressed, and activated in the Delta mexF and Delta mexB Delta mexF mutant strains. The swarming and swimming motilities were impaired in Delta mexF and Delta mexB Delta rnexF mutants. The flood inoculation test indicated that bacterial populations in all mutant strains were significantly lower than that of WT, although all mutants and WT caused similar disease symptoms. These results indicate that MexAB-OprM extrudes plant-derived catechol, acetovanillone, or coumarin, and contributes to bacterial virulence. Furthermore, MexAB-OprM and MexEF-OprN complemented each other's functions to some extent.

DOI： 10.5423/PPJ.OA.11.2019.0273

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER JAPAN KK  

Quorum sensing (QS) is a mechanism for bacterial cell-cell communication using QS signals. N-acyl-homoserine lactones (AHLs), QS signals in Pseudomonas syringae pv. tabaci (Pta) 6605, are synthesized by an AHL synthase (PsyI) and recognized by the cognate transcription factor PsyR. To reveal the role of PsyR in virulence, we generated a psyR mutant and complemented strains of Pta 6605 and found that the psyR mutant is remarkably reduced in AHL production and ability to cause disease and propagate in host tobacco leaves. The phenotypes of complemented strains were restored to that of the wild type (WT). Because the psyR mutant lost nearly all AHL production, we investigated the function of PsyR in the transcription of psyI and production of AHL. Electrophoretic mobility shift assays suggested that the recombinant PsyR protein binds the promoter region of psyI but not psyR without AHL. The addition of AHL did not significantly affect this binding. The binding core sequence of this region was identified as a 20-bp lux box-like sequence. To reveal the function of PsyR and AHL on psyI transcription, we constructed a psyI promoter::lacZYA chimeric reporter gene, and inserted it into the WT and psyI mutant of Pta 6605. beta-galactosidase activity increased in a bacterial density-dependent manner in the WT and also in a psyI mutant after the addition of exogenous AHL. These results indicate that the solo PsyR binds the lux box in the psyI promoter and activates transcription in the concomitant presence of AHL.

DOI： 10.1007/s10327-019-00893-3

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

γ-Aminobutyric acid (GABA) is a widely distributed non-proteinogenic amino acid that accumulates in plants under biotic and abiotic stress conditions. Recent studies suggested that GABA also functions as an intracellular signaling molecule in plants and in signals mediating interactions between plants and phytopathogenic bacteria. However, the molecular mechanisms underlying GABA responses to bacterial pathogens remain unknown. In the present study, a GABA receptor, named McpG, was conserved in the highly motile plant-pathogenic bacteria Pseudomonas syringae pv. tabaci 6605 (Pta6605). We generated a deletion mutant of McpG to further investigate its involvement in GABA chemotaxis using quantitative capillary and qualitative plate assays. The wild-type strain of Pta6605 was attracted to GABA, while the ΔmcpG mutant abolished chemotaxis to 10‍ ‍mM GABA. However, ΔmcpG retained chemotaxis to proteinogenic amino acids and succinic semialdehyde, a structural analog of GABA. Furthermore, ΔmcpG was unable to effectively induce disease on host tobacco plants in three plant inoculation assays: flood, dip, and infiltration inoculations. These results revealed that the GABA sensing of Pta6605 is important for the interaction of Pta6605 with its host tobacco plant.

DOI： 10.1264/jsme2.ME20114

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER JAPAN KK  

PRX34 mediates the oxidative burst in Arabidopsis. Here we characterized two additional Arabidopsis prx34 null mutants (prx34-2, prx34-3), besides the well-studied prx34-1. Due to a decrease in corresponding peroxidase, the activity that generates reactive oxygen species (ROS) was significantly lower in cell wall extracts of prx34-2 and prx34-3 plants. Consistently, the prx34-2 and prx34-3 exhibited reduced accumulation both of ROS and callose in Flg22-elicitor-treated leaves, leading to enhanced susceptibility to bacterial and fungal pathogens. In contrast, ectopic expression of PRX34 in the wild type caused enhanced resistance. PRX34 is thus a component for disease resistance in Arabidopsis.

DOI： 10.1007/s10327-019-00863-9

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：American Association for the Advancement of Science (AAAS)  

Plants and animals recognize conserved flagellin fragments as a signature of bacterial invasion. These immunogenic elicitor peptides are embedded in the flagellin polymer and require hydrolytic release before they can activate cell surface receptors. Although much of flagellin signaling is understood, little is known about the release of immunogenic fragments. We discovered that plant-secreted β-galactosidase 1 (BGAL1) of Nicotiana benthamiana promotes hydrolytic elicitor release and acts in immunity against pathogenic Pseudomonas syringae strains only when they carry a terminal modified viosamine (mVio) in the flagellin O-glycan. In counter defense, P. syringae pathovars evade host immunity by using BGAL1-resistant O-glycans or by producing a BGAL1 inhibitor. Polymorphic glycans on flagella are common to plant and animal pathogenic bacteria and represent an important determinant of host immunity to bacterial pathogens.

DOI： 10.1126/science.aav0748

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Jasmonic acid (JA) plays an important role in the induction of herbivore resistance in many plants. However, JA-independent herbivore resistance has been suggested. An herbivore-resistance-inducing substance was isolated from Tobacco mosaic virus-infected tobacco (Nicotiana tabacum) leaves in which a hypersensitive response (HR) was induced and identified as loliolide, which has been identified as a β-carotene metabolite. When applied to tomato (Solanum lycopersicum) leaves, loliolide decreased the survival rate of the two-spotted spider mite, Tetranychus urticae, egg deposition by the same pest, and the survival rate of larvae of the common cutworm Spodoptera litura without exhibiting toxicity against these herbivores. Endogenous loliolide levels increased not only with an infestation by Slitura larvae, but also with the exogenous application of their oral secretions in tomato. A microarray analysis identified cell-wall-associated defense genes as loliolide-responsive tomato genes, and exogenous JA application did not induce the expression of these genes. Suppressor of zeaxanthin-less (szl), an Arabidopsis (Arabidopsis thaliana) mutant with a point mutation in a key gene of the β-carotene metabolic pathway, exhibited the decreased accumulation of endogenous loliolide and increased susceptibility to infestation by the western flower thrip (Frankliniella occidentalis). A pretreatment with loliolide decreased susceptibility to thrips in the JA-insensitive Arabidopsis mutant coronatine-insensitive1 Exogenous loliolide did not restore reduced electrolyte leakage in szl in response to a HR-inducing bacterial strain. These results suggest that loliolide functions as an endogenous signal that mediates defense responses to herbivores, possibly independently of JA, at least in tomato and Arabidopsis plants.

DOI： 10.1104/pp.18.00837

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.micres.2019.04.004

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1007/s00438-018-1430-9

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：BIO-PROTOCOL  

Pseudomonas syringae pv. tomato strain DC3000 (Pto DC3000), which causes bacterial speck disease of tomato, has been used as a model pathogen because of its pathogenicity on Arabidopsis thaliana. Here, we demonstrate a rapid and reliable flood-inoculation method based on young Arabidopsis seedlings grown on one-half strength MS medium. We also describe a method to evaluate the bacterial growth in Arabidopsis.

DOI： 10.21769/BioProtoc.2106

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER PHYTOPATHOLOGICAL SOC  

Reactive oxygen species (ROS) have been shown to have a crucial role in plant defense responses and signaling pathways. In addition, ROS also have direct toxicity against pathogens. However, the molecular mechanisms of plant ROS in the direct effects against pathogens is still unclear. To investigate the function of plant ROS in the interactions of plant and bacterial pathogens, we focused on oxyR, encoding an oxidative stress regulated transcription factor in Pseudomonas syringae pv. tomato DC3000 (DC3000), and generated an Delta oxyR mutant. The DC3000 Delta oxyR mutant showed high sensitivity to oxidative stress in comparison with wild type and the complemented line. The host plants of DC3000, including tomato and Arabidopsis inoculated with the Delta oxyR mutant, clearly showed reduced disease symptoms as well as reduced bacterial populations. Expression profiles of DC3000 genes revealed that OxyR could regulate the expression of genes encoding ROS-detoxifying enzymes, including catalases (KatB and KatG), in response to ROS. We also demonstrated that the expression of katB could be regulated by OxyR during the infection of DC3000 in Arabidopsis. These results suggest that OxyR has an important role in the virulence of DC3000 by regulating the expression of genes related to oxidative stress.

DOI： 10.1094/MPMI-09-15-0204-R

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.pmpp.2016.02.005

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1111/mpp.12187

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1111/mpp.12079

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：WILEY-BLACKWELL  

The bacterial flagellin (FliC) epitopes flg22 and flgII-28 are microbe-associated molecular patterns (MAMPs). Although flg22 is recognized by many plant species via the pattern recognition receptor FLS2, neither the flgII-28 receptor nor the extent of flgII-28 recognition by different plant families is known. Here, we tested the significance of flgII-28 as a MAMP and the importance of allelic diversity in flg22 and flgII-28 in plant-pathogen interactions using purified peptides and a Pseudomonas syringae fliC mutant complemented with different fliC alleles. The plant genotype and allelic diversity in flg22 and flgII-28 were found to significantly affect the plant immune response, but not bacterial motility. The recognition of flgII-28 is restricted to a number of solanaceous species. Although the flgII-28 peptide does not trigger any immune response in Arabidopsis, mutations in both flg22 and flgII-28 have FLS2-dependent effects on virulence. However, the expression of a tomato allele of FLS2 does not confer to Nicotiana benthamiana the ability to detect flgII-28, and tomato plants silenced for FLS2 are not altered in flgII-28 recognition. Therefore, MAMP diversification is an effective pathogen virulence strategy, and flgII-28 appears to be perceived by an as yet unidentified receptor in the Solanaceae, although it has an FLS2-dependent virulence effect in Arabidopsis.

DOI： 10.1111/nph.12408

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Glycosylation of flagellin is known to be involved in filament stabilization, motility, and virulence in Pseudomonas syringae. Here we investigated flagellin glycosylation in other phytopathogenic bacteria. Analyses of deduced amino acid sequences, glycostaining, and molecular masses of purified flagellins revealed that flagellins from all phytopathogenic bacteria investigated were glycosylated. Furthermore, the flagellin in a glycosylation-defective mutant of Xanthomonas campestris pv. campestris (Xcc) had a reduced molecular mass, and motility and virulence of the mutant toward host leaves decreased. These results suggest that flagellin glycosylation is ubiquitous in most phytopathogenic bacteria and that flagellin glycosylation is required for virulence in Xcc. © 2013 The Phytopathological Society of Japan and Springer Japan.

DOI： 10.1007/s10327-013-0464-4

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.carres.2013.04.018

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Virulence factor regulator (Vfr) is a member of the cyclic 3′,5′-adenosine monophosphate (cAMP) receptor proteins that regulate the expression of many important virulence genes in Pseudomonas aeruginosa. The role of Vfr in pathogenicity has not been elucidated fully in phytopathogenic bacteria. To investigate the function of Vfr in Pseudomonas syringae pv. tabaci 6605, the vfr gene was disrupted. The virulence of the vfr mutant towards host tobacco plants was attenuated significantly, and the intracellular cAMP level was decreased. The vfr mutant reduced the expression of flagella-, pili- and type III secretion system-related genes and the defence response in nonhost Arabidopsis leaves. Furthermore, the expression levels of achromobactin-related genes and the iron uptake ability were decreased, suggesting that Vfr regulates positively these virulence-related genes. In contrast, the vfr mutant showed higher tolerance to antimicrobial compounds as a result of the enhanced expression of the resistance-nodulation-division family members, the mexA, mexB and oprM genes. We further demonstrated that the mutant strains of vfr and cyaA, an adenylate cyclase gene responsible for cAMP synthesis, showed a similar phenotype, suggesting that Vfr regulates virulence factors in a cAMP-dependent manner. Because there was no significant difference in the production of acylhomoserine lactone (AHL) quorum sensing molecules in the wild-type, vfr and cyaA mutant strains, Vfr might control important virulence factors by an AHL-independent mechanism in an early stage of infection by this bacterium. © 2012 The Authors. Molecular Plant Pathology © 2012 Bspp and Blackwell Publishing Ltd.

DOI： 10.1111/mpp.12003

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

Type IV pilin (PilA) is a major constituent of pilus and is required for bacterial biofilm formation, surface motility and virulence. It is known that mature PilA is produced by cleavage of the short leader sequence of the pilin precursor, followed by methylation of N-terminal phenylalanine. The molecular mass of the PilA mature protein from the tobacco bacterial pathogen Pseudomonas syringae pv. tabaci 6605 (Pta 6605) has been predicted to be 12 329 Da from its deduced amino acid sequence. Previously, we have detected PilA as an approximately 13-kDa protein by immunoblot analysis with anti-PilA-specific antibody. In addition, we found the putative oligosaccharide-transferase gene tfpO downstream of pilA. These findings suggest that PilA in Pta 6605 is glycosylated. The defective mutant of tfpO (ΔtfpO) shows reductions in pilin molecular mass, surface motility and virulence towards host tobacco plants. Thus, pilin glycan plays important roles in bacterial motility and virulence. The genetic region around pilA was compared among P. syringae pathovars. The tfpO gene exists in some strains of pathovars tabaci, syringae, lachrymans, mori, actinidiae, maculicola and P. savastanoi pv. savastanoi. However, some strains of pathovars tabaci, syringae, glycinea, tomato, aesculi and oryzae do not possess tfpO, and the existence of tfpO is independent of the classification of pathovars/strains in P. syringae. Interestingly, the PilA amino acid sequences in tfpO-possessing strains show higher homology with each other than with tfpO-nonpossessing strains. These results suggest that tfpO and pilA might co-evolve in certain specific bacterial strains.

DOI： 10.1111/j.1364-3703.2012.00789.x

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：MDPI AG  

Previously we revealed that flagellin proteins in Pseudomonas syringae pv. tabaci 6605 (Pta 6605) were glycosylated with a trisaccharide, modified viosamine (mVio)-rhamnose-rhamnose and that glycosylation was required for virulence. We further identified some glycosylation-related genes, including vioA, vioB, vioT, fgt1, and fgt2. In this study, we newly identified vioR and vioM in a so-called viosamine island as biosynthetic genes for glycosylation of mVio in Pta 6605 by the mass spectrometry (MS) of flagellin glycan in the respective mutants. Furthermore, characterization of the mVio-related genes and MS analyses of flagellin glycans in other pathovars of P. syringae revealed that mVio-related genes were essential for mVio biosynthesis in flagellin glycans, and that P. syringae pv. syringae B728a, which does not possess a viosamine island, has a different structure of glycan in its flagellin protein.

DOI： 10.3390/genes2040788

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER PHYTOPATHOLOGICAL SOC  

To investigate the role of type IV pili in the virulence of phytopathogenic bacteria, four mutant strains for pilus biogenesis-related genes were generated in Pseudomonas syringae pv. tabaci 6605. PilA encodes the pilin protein as a major subunit of type IV pili, and the pilO product is reported to be required for pilus assembly. The fimU and fimT genes are predicted to produce minor pilins. Western blot analysis revealed that pilA, pilO, and fimU mutants but not the fluff mutant failed to construct type IV phi. Although the swimming motility of all mutant strains was not impaired in liquid medium, they showed remarkably reduced motilities on semisolid agar medium, suggesting that type IV pili are required for surface motilities. Virulence toward host tobacco plants and hypersensitive response-inducing ability in nonhost Arabidopsis leaves of pilA, pilO, and fimU mutant strains were reduced. These results might be a consequence of reduced expression of type Ill secretion system-related genes in the mutant strains. Further, all mutant strains showed enhanced expression of resistance-nodulation-division family members mexA, mexB, and oprM, and higher tolerance to antimicrobial compounds. These results indicate that type IV pili are an important virulence factor of this pathogen.

DOI： 10.1094/MPMI-02-11-0026

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担当区分：最終著者,　責任著者   記述言語：英語  

DOI： 10.1007/s00438-010-0594-8

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担当区分：最終著者,　責任著者   記述言語：英語  

DOI： 10.1111/j.1364-3703.2011.00705.x

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DOI： 10.1099/mic.0.030700-0

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掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer Science and Business Media LLC  

DOI： 10.1186/1471-2164-11-210

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担当区分：最終著者,　責任著者  

Glycosylation of flagellin contributes to swimming and swarming motilities, adhesion ability, and consequently virulence in Pseudomonas syringae pv. tabaci 6605. Glycans attached to six serine residues are located in the central region of the flagellin polypeptide. The glycan structure at position Ser 201 was recently revealed to consist of two l-rhamnoses and one modified 4-amino-4,6-dideoxyglucose (viosamine). To clarify the mechanisms for glycosylation of modified viosamine, genes encoding dTDP-viosamine aminotransferase (vioA), dTDP-viosamine acetyltransferase (vioB), and viosamine-derivative transferase (vioT) were isolated and defective mutants were generated. MALDI-TOF-MS analysis of a lysyl endopeptidase-digested peptide including all six glycosylation sites from each flagellin indicated that the molecular masses of the three flagellin mutants were reduced with highly heterogeneous patterns at regular intervals of 146 Da in the mass range from m/z 13,819 to 15,732. The data indicated that the glycopeptides obtained from mutants had glycans consisting only of deoxyhexose instead of the flagellin glycans including the viosamine derivatives determined previously. The motility and virulence on host tobacco leaves were strongly impaired in the ΔvioA mutant and were weakly reduced in the ΔvioB and ΔvioT mutant strains. These results suggest that the genes vioA, vioB, and vioT are essential for glycosylation of flagellin, and accordingly are required for bacterial virulence. © 2009 Springer-Verlag.

DOI： 10.1007/s00438-009-0489-8

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER TOKYO  

DOI： 10.1007/s10327-009-0192-y

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.pmpp.2009.08.001

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記述言語：日本語   出版者・発行元：日本植物病理學會  

植物病原細菌Pseudomonas syringaeには宿主や病徴を異にする多くの病原型が存在し、宿主植物の葉や茎、果実の傷口、気孔などから侵入後、細胞間隙で増殖・移動し、主に斑点・褐変・枯死を引き起こす。これまでに50以上の病原型が報告され、それら病原型はそれぞれ固有の宿主植物に感染が可能である。例えば、タバコ野火病菌（以下Pta6605と略す）はタバコ葉に淡黄色水浸状小斑点を生じ、その周辺に黄化を引き起こすものの、ダイズやトマト、シロイヌナズナには非病原性である。植物病原細菌の非宿主植物に対する過敏感反応（HR）誘導能と宿主植物に対する病原性に必要な領域として、hrp遺伝子クラスターが知られている。hrp遺伝子クラスターには、Type III分泌経路を構成するタンパク質遺伝子、hrp遺伝子の制御因子遺伝子の他、非宿主植物に過敏感反応を誘導するタンパク質エリシターharpinをコードするhrpZなどが存在する。私たちはP. syringaeのいくつかの病原型細菌においてhrpZ遺伝子を調べたところ、Pta6605のhrpZは中央部に326塩基の内部欠損とそれに伴うフレームシフトを起こしており、HR誘導能を欠失していることを見出した。HarpinはP. syringaeの非宿主植物に対する主要なHR誘導因子であると考えられていたが、Pta6605を非宿主植物に高濃度で接種するとHRが誘導されることより、Pta6605にはharpin以外のエリシターが存在すると推察された。そこで、Pta6605の培養上清からトマトに対し、HRを誘導する分子の検索を行い、鞭毛構成タンパク質フラジェリンを同定した。

DOI： 10.3186/jjphytopath.75.147

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その他リンク： http://agriknowledge.affrc.go.jp/RN/2010780609

担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER SOC MICROBIOLOGY  

Flagellins from Pseudomonas syringae pv. glycinea race 4 and Pseudomonas syringae pv. tabaci 6605 have been found to be glycosylated. Glycosylation of flagellin is essential for bacterial virulence and is also involved in the determination of host specificity. Flagellin glycans from both pathovars were characterized, and common sites of glycosylation were identified on six serine residues (positions 143, 164, 176, 183, 193, and 201). The structure of the glycan at serine 201 (S201) of flagellin from each pathovar was determined by sugar composition analysis, mass spectrometry, and (1)H and (13)C nuclear magnetic resonance spectroscopy. These analyses showed that the S201 glycans from both pathovars were composed of a common unique trisaccharide consisting of two rhamnosyl (Rha) residues and one modified 4-amino-4,6-dideoxyglucosyl (Qui4N) residue, beta-D-Quip4N(3-hydroxy-1-oxobutyl)2Me-(1-->3)-alpha-L-Rhap-(1-->2)-alpha-L-Rhap. Furthermore, mass analysis suggests that the glycans on each of the six serine residues are composed of similar trisaccharide units. Determination of the enantiomeric ratio of Rha from the flagellin proteins showed that flagellin from P. syringae pv. tabaci 6605 consisted solely of L-Rha, whereas P. syringae pv. glycinea race 4 flagellin contained both L-Rha and D-Rha at a molar ratio of about 4:1. Taking these findings together with those from our previous study, we conclude that these flagellin glycan structures may be important for the virulence and host specificity of P. syringae.

DOI： 10.1128/JB.00500-07

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：BLACKWELL PUBLISHING  

A glycosylation island is a genetic region required for glycosylation. The glycosylation island of flagellin in Pseudomonas syringae pv. tabaci 6605 consists of three orfs: orf1, orf2 and orf3. Orf1 and orf2 encode putative glycosyltransferases, and their deletion mutants, Deltaorf1 and Deltaorf2, exhibit deficient flagellin glycosylation or produce partially glycosylated flagellin respectively. Digestion of glycosylated flagellin from wild-type bacteria and non-glycosylated flagellin from Deltaorf1 mutant using aspartic N-peptidase and subsequent HPLC analysis revealed candidate glycosylated amino acids. By generation of site-directed Ser/Ala-substituted mutants, all glycosylated amino acid residues were identified at positions 143, 164, 176, 183, 193 and 201. Matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectrometry (MS) analysis revealed that each glycan was about 540 Da. While all glycosylation-defective mutants retained swimming ability, swarming ability was reduced in the Deltaorf1, Deltaorf2 and Ser/Ala-substituted mutants. All glycosylation mutants were also found to be impaired in the ability to adhere to a polystyrene surface and in the ability to cause disease in tobacco. Based on the predicted tertiary structure of flagellin, S176 and S183 are expected to be located on most external surface of the flagellum. Thus the effect of Ala-substitution of these serines is stronger than that of other serines. These results suggest that glycosylation of flagellin in P. syringae pv. tabaci 6605 is required for bacterial virulence. It is also possible that glycosylation of flagellin may mask elicitor function of flagellin molecule.

DOI： 10.1111/j.1462-5822.2005.0674.x

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1128/JB.22.6658-6665.2003

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1007/s00438-003-0817-3

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掲載種別：研究論文（学術雑誌）   出版者・発行元：Oxford University Press (OUP)  

Abstract

Tailocins are headless phage tail structures that mediate interbacterial antagonism. Although the prototypical tailocins, R- and F-pyocins, in Pseudomonas aeruginosa, and other predominantly R-type tailocins have been studied, their presence in Alphaproteobacteria remains unexplored. Here, we report the first alphaproteobacterial F-type tailocin, named rhizoviticin, as a determinant of the biocontrol activity of Allorhizobium vitis VAR03-1 against crown gall. Rhizoviticin is encoded by a chimeric prophage genome, one providing transcriptional regulators and the other contributing to tail formation and cell lysis, but lacking head formation genes. The rhizoviticin genome retains a nearly intact early phage region containing an integrase remnant and replication-related genes critical for downstream gene transcription, suggesting an ongoing transition of this locus from a prophage to a tailocin-coding region. Rhizoviticin is responsible for the most antagonistic activity in VAR03-1 culture supernatant against pathogenic A. vitis strain, and rhizoviticin deficiency resulted in a significant reduction in the antitumorigenic activity in planta. We identified the rhizoviticin-coding locus in eight additional A. vitis strains from diverse geographical locations, highlighting a unique survival strategy of certain Rhizobiales bacteria in the rhizosphere. These findings advance our understanding of the evolutionary dynamics of tailocins and provide a scientific foundation for employing rhizoviticin-producing strains in plant disease control.

DOI： 10.1093/ismejo/wrad003

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掲載種別：研究論文（学術雑誌）  

DOI： 10.3390/microorganisms11041025

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掲載種別：研究論文（学術雑誌）   出版者・発行元：Frontiers Media {SA}  

<jats:p>Plants protect themselves from microorganisms by inducing pattern-triggered immunity (PTI) <jats:italic>via</jats:italic> recognizing microbe-associated molecular patterns (MAMPs), conserved across many microbes. Although the MAMP perception mechanism and initial events during PTI have been well-characterized, knowledge of the transcriptomic changes in plants, especially monocots, is limited during the intermediate and terminal stages of PTI. Here, we report a time-series high-resolution RNA-sequencing (RNA-seq) analysis during PTI in the leaf disks of <jats:italic>Brachypodium distachyon</jats:italic>. We identified 6,039 differentially expressed genes (DEGs) in leaves sampled at 0, 0.5, 1, 3, 6, and 12 hours after treatment (hat) with the bacterial flagellin peptide flg22. The k-means clustering method classified these DEGs into 10 clusters (6 upregulated and 4 downregulated). Based on the results, we selected 10 PTI marker genes in <jats:italic>B. distachyon</jats:italic>. Gene ontology (GO) analysis suggested a tradeoff between defense responses and photosynthesis during PTI. The data indicated the recovery of photosynthesis started at least at 12 hat. Over-representation analysis of transcription factor genes and cis-regulatory elements in DEG promoters implied the contribution of 12 WRKY transcription factors in plant defense at the early stage of PTI induction.</jats:p>

DOI： 10.3389/fpls.2022.1004184

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： https://doi.org/10.1007/s10327-022-01077-2

掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer Science and Business Media LLC  

DOI： 10.1007/s10327-022-01077-2

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その他リンク： https://link.springer.com/article/10.1007/s10327-022-01077-2/fulltext.html

記述言語：英語   掲載種別：研究論文（学術雑誌）  

掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer Science and Business Media LLC  

<title>Abstract</title>
<italic>Rhizoctonia solani</italic> is a necrotrophic phytopathogen belonging to basidiomycetes. It causes rice sheath blight which inflicts serious damage in rice production. The infection strategy of this pathogen remains unclear. We previously demonstrated that salicylic acid-induced immunity could block <italic>R. solani</italic> AG-1 IA infection in both rice and <italic>Brachypodium distachyon</italic>. <italic>R. solani</italic> may undergo biotrophic process using effector proteins to suppress host immunity before necrotrophic stage. To identify pathogen genes expressed at the early infection process, here we developed an inoculation method using <italic>B. distachyon</italic> which enables to sample an increased amount of semi-synchronous infection hyphae. Sixty-one <italic>R. solani secretory effector-like protein</italic> genes (<italic>RsSEPGs</italic>) were identified using in silico approach with the publicly available gene annotation of <italic>R. solani</italic> AG-1 IA genome and our RNA-sequencing results obtained from hyphae grown on agar medium. Expression of <italic>RsSEPGs</italic> was analyzed at 6, 10, 16, 24, and 32 h after inoculation by a quantitative reverse transcription-polymerase chain reaction and 52 genes could be detected at least on a single time point tested. Their expressions showed phase-specific patterns which were classified into 6 clusters. The 23 <italic>RsSEPGs</italic> in the cluster 1–3 and 29 <italic>RsSEPGs</italic> in the cluster 4–6 are expected to be involved in biotrophic and necrotrophic interactions, respectively.

DOI： 10.1038/s41598-020-71968-x

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その他リンク： http://www.nature.com/articles/s41598-020-71968-x

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER JAPAN KK  

An ethyl acetate extract of Arabidopsis thaliana plants was tested for the presence of endogenous suppressor(s) (ES), and the active fraction, which partitioned into water phase contained a molecule(s) < 3000 Da based on a rough estimate using sized membrane filters. Foliar application of the ES enabled typically nonpathogenic fungi (non-adapted pathogens) to cause disease symptoms on A. thaliana. Consistently, the ES fraction severely suppressed the oxidative burst and the expression of defense-related genes such as FRK1, NHO1, WRKY22, WRKY29, PEN2, and PEN3 in plants challenged with non-adapted fungus Colletotrichum gloeosporioides or the fungal elicitor chitin.

DOI： 10.1007/s10327-019-00897-z

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER JAPAN KK  

Saccharin and its parental compound probenazole (PBZ) are plant activators of effective defense responses to (hemi) biotrophic pathogens. Here, we demonstrate that pretreatment of wheat seedlings with saccharin or PBZ results in a significant reduction of powdery mildew caused by Blumeria graminis f. sp. tritici. Transcriptional analysis revealed the expression of 15 defense-related genes including PR genes, WCI genes, LOX, AOS, NPR1, PAL and WRKY genes in wheat seedlings exposed to either saccharin or PBZ. Moreover, the saccharin- and PBZ-enhanced expression of those genes during fungal infection further proved a close correlation with increased resistance in wheat.

DOI： 10.1007/s10327-019-00900-7

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER JAPAN KK  

Saccharin is generated from probenazole (PBZ) in plants and acts as a plant defense activator. Our study of the mechanism underlying saccharin-induced systemic acquired resistance in Arabidopsis thaliana suggests an antagonistic interaction between salicylic acid (SA)- and jasmonic acid (JA)-signaling as revealed through gene expression analyses. In wild-type plants (Col-0) exposed to saccharin, there was a consistent increase in callose deposition and in expression of SA-marker genes, PR1 and PR2, which coincided with a decrease in expression of JA-marker genes such as VSP2, LOX2 and PDF1.2. Actually, pretreatment of Col-0 with saccharin or PBZ conferred resistance to Pseudomonas syringae pv. tomato DC3000, but not to Pectobacterium carotovorum subsp. carotovorum, Botrytis cinerea, or Colletotrichum higginsianum. Enhanced expression of SA- and JA-marker genes and the augmented deposition of callose were evident after a challenge with virulent DC3000 in saccharin-pretreated plants. Consistently, pretreatment of saccharin and PBZ with SA- and JA-defective mutants led to diminished resistance in NahG-transgenic and npr1 mutant plants, but not in jar1 mutant plants, suggesting that saccharin and PBZ induce resistance in A. thaliana against Pto DC3000 mainly via activation of SA-signaling, leading to suppression of JA/ET-signaling and vice versa. Collectively, an antagonism between SA- and JA-signaling conditioned by saccharin renders resistance to a specific pathogen in Arabidopsis.

DOI： 10.1007/s10327-019-00899-x

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.micres.2018.06.005

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1111/nph.14849

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その他リンク： http://orcid.org/0000-0002-4481-6189

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1007/s10327-017-0756-1

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER PHYTOPATHOLOGICAL SOC  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：FRONTIERS MEDIA SA  

Ascochyta (Mycosphaerella) blight on cultivated peas is primarily caused by infection through asexual spores (pycnospores) of Mycosphaerella pinodes (Berk. et Blox.) Vestergren [recently renamed Peyronellaea pinodes (Berk. & A. Bloxam) Aveskamp, Gruyter & Verkley]. Using a model pathosystem involving Medicago truncatula and Mycosphaerella pinodes strain OMP-1, we examined the histology and ultrastructure of early infection events and fungal development including penetration by appressoria, vegetative growth of infection hyphae, and host responses. On the susceptible ecotype R108-1, pycnospores germinated and grew over the surface of the epidermis, then formed an appressoria and penetrated the cuticle. Beneath the cuticle, the infection peg expanded into a hyphae that grew within the outer wall of the epidermis. Subsequently, the hyphae penetrated down within mesophyll cells and proliferated vigorously, eventually, forming asexual fruiting bodies (pycnidia). In contrast, successful penetration and subsequent growth of infection hyphae were considerably restricted in the ecotype Caliph. Detected by its reaction with cerium chloride (CeCl3) to generate electron-dense cerium perhydroxides in transmission electron micrographs, hydrogen peroxide (H2O2) accumulated in epidermal and mesophyll cells of Caliph challenged with pycnospores of M. pinodes. This intracellular localization was confirmed by energydispersive X-ray spectroscopy. Our observations thus indicate that the oxidative burst reaction leading to the generation of reactive oxygen species is associated with a local host defense response in Caliph, since no clear H2O2 accumulation was detectable in susceptible R108-1. Indeed, aberrant hyphae such as intrahyphal hyphae and dead hyphae, probably due to a local defense elicited by the fungus, were abundant in Caliph but not in R108-1. Our results on the cellular interactions between the fungus and host cells provide additional insights to understand foliar infection by M. pinodes on cultivated peas.

DOI： 10.3389/fpls.2017.01132

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担当区分：最終著者,　責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1186/s12870-016-0749-9

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.pmpp.2016.02.006

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DOI： 10.1007/s10327-015-0621-z

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1007/s10327-014-0510-x

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記述言語：日本語   出版者・発行元：日本植物病理学会  

DOI： 10.3186/jjphytopath.80.146

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その他リンク： http://id.ndl.go.jp/bib/025814697

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：TAYLOR & FRANCIS LTD  

D-rhamnose (D-Rha) residue is a major component of lipopolysaccharides (LPSs) in strains of the phytopathogen Pseudomonas syringae pathovar glycinea. To investigate the effects of a deficiency in GDP-D-rhamnose biosynthetic genes on LPS structure and pathogenicity, we generated three mutants defective in D-Rha biosynthetic genes, encoding proteins GDP-D-mannose 4,6-dehydratase (GMD), GDP-4-keto-6-deoxy-D-mannose reductase (RMD), and a putative alpha-D-rhamnosyltransferase (WbpZ) in P. syringae pv. glyeinea race 4. The Delta gmd, Delta rmd, and Delta wbpZ mutants had a reduced O-antigen polysaccharide consisting of D-Rha residues as compared with the wild type (WT). The swarming motility of the Delta gmd, Delta rmd, and Delta wbpZ mutant strains decreased and hydrophobicity and adhesion ability increased as compared with WT. Although the mutants had truncated O-antigen polysaccharides, and altered surface properties, they showed virulence to soybean, as WT did.

DOI： 10.1271/bbb.120736

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DOI： 10.1007/s10327-013-0460-8

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記述言語：日本語   掲載種別：研究論文（大学，研究機関等紀要）   出版者・発行元：岡山大学農学部  

A plant growth-promoting fungus was isolated from an agricultural field in Okayama Prefecture, Japan. The strain FS2, which enhanced seed germination, root elongation and leaf growth of Brassica rapa var. perviridis, was identified as Talaromyces wortmannii based on ITS1 sequence and its morphology.
本研究では，実際の生産圃場から植物生育促進菌（PGPF）の探索を試み，コマツナの生育を促進するFS2株を分離した．FS2株の形態観察並びにのITS1領域の系統樹解析から本菌をTalaromyces wortmanniiと同定した．

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記述言語：日本語   掲載種別：研究論文（大学，研究機関等紀要）   出版者・発行元：岡山大学農学部  

A plant growth-promoting fungus, Talaromyces wortmannii strain FS2 was isolated from an agricultural field at Okayama Pref. FS2 enhanced seed germination, root elongation and leaf growth of Brassica rapa var perviridis (Komatsuna). Such plant growth-promoting effect was observed in the same sealed chamber where FS2 was cultured on PDA medium separated from seedlings, suggesting effective volatile compound(s). GC‒MS analysis showed that FS2 emitted at least seven terpenoids, of which a volatile was identified as β‒caryophyllene. β‒caryophyllene alone promoted the growth of cucumber, Nicotiana benthamiana and barley. Furthermore β‒caryophyllene increased the yield of cucumber fruits. Interestingly, we found that β‒caryophyllene conditioned these plants to be resistant to respective diseases caused by Colletotrichum orbiculare, Botrytis cinerea or Blumeria graminis f. sp hordei. The findings indicate that β‒caryophyllene has desirable dual features and therefore, it is available to cultivation of many crops.
岡山県総社市の圃場から分離した植物生育促進菌Talaromyces wortmannii FS2が生産するβ-caryophylleneは，コマツナ（アブラナ科）のみならず，キュウリ（ウリ科），タバコ（ナス科）およびオオムギ（イネ科）など広汎な植物に対して，生育促進作用および耐病性増進作用を示したことから，有用な農業資材として利用可能であるものと考察した．

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DOI： 10.1007/s10327-012-0405-7

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DOI： 10.1007/s10327-012-0418-2

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DOI： 10.1007/s10327-012-0412-8

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掲載種別：研究論文（学術雑誌）  

The soil-borne bacterial pathogen Ralstonia solanacearum invades a broad range of plants through their roots, resulting in wilting of the plant, but no effective protection against this disease has been developed. Two bacterial wilt disease-inhibiting compounds were biochemically isolated from tobacco and identified as sclareol and cis-abienol, labdane-type diterpenes. When exogenously applied to their roots, sclareol and cis-abienol inhibited wilt disease in tobacco, tomato and Arabidopsis plants without exhibiting any antibacterial activity. Microarray analysis identified many sclareol-responsive genes in Arabidopsis roots, including genes encoding or with a role in ATP-binding cassette (ABC) transporters, and biosynthesis and signaling of defense-related molecules and mitogen-activated protein kinase (MAPK) cascade components. Inhibition of wilt disease by sclareol was attenuated in Arabidopsis mutants defective in the ABC transporter AtPDR12, the MAPK MPK3, and ethylene and abscisic acid signaling pathways, and also in transgenic tobacco plants with reduced expression of NtPDR1, a tobacco homolog of AtPDR12. These results suggest that multiple host factors are involved in the inhibition of bacterial wilt disease by sclareol-related compounds. © The Author 2012. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists.

DOI： 10.1093/pcp/pcs085

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1007/s00438-012-0693-9

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DOI： 10.1007/s10327-012-0399-1

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1007/s10327-011-0340-z

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCI LTD  

The flagellin of Pseudomonas syringae pv. tabaci is a glycoprotein that contains O-linked oligosaccharides composed of rhamnosyl and 4,6-dideoxy-4-(3-hydroxybutanamido)-2-O-methylglucosyl residues. These O-linked glycans are released by hydrazinolysis and then labeled at their reducing ends with 2-aminopyridine (PA). A PA-labeled trisaccharide and a PA-labeled tetrasaccharide are isolated by normal-phase high-performance liquid chromatography. These oligosaccharides are structurally characterized using mass spectrometry and NMR spectroscopy. Our data show that P. syringae pv. tabaci flagellin is glycosylated with a tetrasaccharide, 4,6-dideoxy-4-(3-hydroxybutanamido)-2-O-methyl-Glcp-(1 -&gt; 3)-alpha-L-Rhap-(1 -&gt; 2)-alpha-L-Rhap-(1 -&gt; 2)-alpha-L-Rha-(1 -&gt;, as well a trisaccharide, 4,6-dideoxy-4-(3-hydroxybutanamido)-2-O-methyl-Glcp-(1 -&gt; 3)-alpha-L-Rhap-(1 -&gt; 2)-alpha-L-Rha-(1 -&gt;,which was identified in a previous study. (C) 2009 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.carres.2009.07.004

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記述言語：日本語   出版者・発行元：日本土壌微生物学会  

DOI： 10.18946/jssm.62.2_143_3

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：OXFORD UNIV PRESS  

Flagellin, a constituent of the flagellar filament, is a potent elicitor of hypersensitive cell death in plant cells. Flagellins of Pseudomonas syringae pvs. glycinea and tomato induce hypersensitive cell death in their non-host tobacco plants, whereas those of P. syringae pv. tabaci do not remarkably induce it in its host tobacco plants. However, the deduced amino acid sequences of flagellins from pvs. tabaci and glycinea are identical, indicating that post-translational modification of flagellins plays an important role in determining hypersensitive reaction (HR)-inducibility. To investigate genetically the role of modification of flagellin in HR-induction, biological and phytopathological phenotypes of a flagella-defective Delta fliC mutant and Delta fliC mutants complemented by the introduction of the flagellin gene (fliC) from different pathovars of P. syringae were investigated. The Delta fliC mutant of pv. tabaci lost flagella, motility, the ability to induce HR cell death in non-host tomato cells and virulence toward host tobacco plants, whereas all pv. tabaci complemented by the introduction of the fliC gene of pvs. tabaci, glycinea or tomato recovered all the abilities that the Delta fliC mutant had lost. These results indicate that post-translational modification of flagellins is strongly correlated with the ability to cause HR cell death.

DOI： 10.1093/pcp/pcg042

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：岡山大學農學部  

エリシターを処理したエンドウ上胚軸由来のRNAから作成されたcDNAライブラリーからエリシター処理により発現が増高する遺伝子候補のcDNAとしてPsDof1が単離された。大腸菌で生産されたGST-PsDof1融合タンパク質はAAAG配列をコアとするDNAに結合することが明らかにされている。本論文では、GST-PsDof1がエリシター応答性遺伝子の一つ、PsCHS1のプロモーター上のAAAGまたはCTTT配列を有する断片に特異的に結合することを明らかにした。更にAAAG配列のエリシター応答性シスエレメントとしての機能を解析するため、AAAG配列を4回繰り返したユニットをCaMV35Sの最小プロモーターとCATレポーター遺伝子に連結したキメラ遺伝子を構築し、エンドウプロトプラストにエレクトロポレーション法により導入した。CAT活性を指標にプロモーター活性を調べたところ、AAAG配列を有するプロモーターは、エリシター処理により活性化されることが明らかとなった。これらの結果はPsDof1がエリシター応答性防御遺伝子のプロモーター上のAAAG配列に結合し、転写を活性化させる可能性を示唆している。
identifier:670005
identifier:ZZ00015342

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その他リンク： http://id.ndl.go.jp/bib/6470981

担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：OXFORD UNIV PRESS  

Suppressors produced by Mycosphaerella pinodes are glycopeptides to block pea defense responses induced by elicitors. A clone, S64, was isolated as cDNA for suppressor-inducible gene from pea epicotyls. The treatment of pea epicotyls with suppressor alone induced an increase of S64 mRNA within 1 h, and it reached a maximum level at 3 h after treatment. The induction was not affected by application of the elicitor, indicating that the suppressor has a dominant action to regulate S64 gene expression. S64 was also induced by inoculation with a virulent pathogen, M. pinodes, but not by inoculation with a non-pathogen, Ascochyta rabiei, nor by treatment with fungal elicitor. The deduced structure of S64 showed high homology to 12-oxophytodienoic acid reductase (OPR) in Arabidopsis thaliana. A recombinant protein derived from S64 had OPR activity, suggesting compatibility-specific activation of the octadecanoid pathway in plants. Treatment with jasmonic acid (JA) or methyl jasmonic acid, end products of the octadecanoid pathway, inhibited the elicitor-induced accumulation of PAL mRNA in pea. These results indicate that the suppressor-induced S64 gene expression leads to the production of JA or related compounds, which might contribute to the establishment of compatibility by inhibiting the phenylpropanoid biosynthetic pathway.

DOI： 10.1093/pcp/pcf144

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

We isolated an INF1 elicitin-inducible cDNA encoding a pleiotropic drug resistance (PDR)-type ATP-binding cassette (ABC) transporter homolog (NtPDR1) in suspension-cultured tobacco Bright Yellow-2 (BY-2) cells by application of differential display PCR. The NtPDR1 (Nicotiana tabacum PDR protein 1) gene also encodes a 162 kDa protein that includes two putative hydrophilic domains containing the ABC signature motif and two putative hydrophobic domains. Expression of the NtPDR1 gene was rapidly and strongly activated by treatment of BY-2 cells with INF1 elicitin. Further, treatment of BY-2 cells with flagellin, a bacterial proteinaceous hypersensitive reaction elicitor, or yeast extract, a general elicitor, also induced NtPDR1 gene expression. These results indicate that NtPDR1 may be involved in the general defense response in tobacco. This is the first report that microbial elicitors induce the expression of a plant ABC transporter gene.

DOI： 10.1016/S0014-5793(02)02697-2

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記述言語：日本語   出版者・発行元：Japan Society for Bioscience, Biotechnology, and Agrochemistry  

DOI： 10.1271/kagakutoseibutsu1962.39.686

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その他リンク： https://jlc.jst.go.jp/DN/JALC/00123241984?from=CiNii

記述言語：英語   掲載種別：研究論文（学術雑誌）  

To enhance bacterial wilt resistance in tobacco expressing a foreign protein, we isolated the bacteriolytic gene from a bacteriophage that infects Ralstonia solanacearum. The bacteriolytic protein of phage P4282 isolated in Tochigi Prefecture was purified from a lysate of R. solanacearum M4S cells infected with the phage, and its bacteriolytic activity was assayed by following the decrease in the turbidity of suspensions of R. solanacearum M4S cells. The molecular weight of the bacteriolytic protein was approximately 71 kDa, and the sequence of the N-terminal 13 amino acids was determined. We used oligonucleotide probes based on this amino acid sequence to isolate the bacteriolytic gene from phage P4282 DNA. This gene of 2061 bp encodes a product of 687 amino acids, whose calaculated molecular weight was 70.12 kDa. The bacteriolytic gene was placed under the control of an inducible promoter, and the plasmid was transformed into Escherichia coli NM522. The soluble proteins extracted from E. coli NM522 cells harboring the plasmid with the bacteriolyric gene showed obvious bacteriolytic activities against several strains of R. solanacearum isolated in various districts in Japan. DNA fragments from five phages, isolated in Niigata, Aomori, Okinawa, Fukushima and Yamaguchi Prefectures, hybridized to the bacteriolytic gene of phage P4282. These observations indicate that the bacteriolytic protein shows nonspecific activity against R. solanacearum strains, and a sequence similar to that of the bacteriolytic gene is conserved in the DNA of other bacteriophages. These results indicate that the generation of transgenic (tobacco) plants expressing the bacteriolytic gene of phage P4282 might result in enhanced resistance to bacterial wilt in tobacco.

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：AMER PHYTOPATHOLOGICAL SOC  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：AMER PHYTOPATHOLOGICAL SOC  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：SPRINGER  

The mechanism of plant host-parasite specificity is one of the most intriguing issues of contemporary plant biology. We recently found that a fungal elicitor stimulated cell wall functions such as ATP-hydrolyzing and superoxide generating activities. Furthermore, the suppressor from Mycosphaerella pinodes inhibited these activities in vitro in a strictly species-specific manner. The cell wall-bound ATPase, which is different from that of the plasma membrane in several properties, was associated with cell wall-bound peroxidase(s). In response to the elicitor, the isolated cell walls are able to produce an infection-inhibitor that may be dependent upon the superoxide generating system. On the other baud, the suppressor inhibited such production in pea cell walls and induced it in nonhost's cell walls. Thus, the effects of both fungal signals on isolated cell walls coincide with those on plant tissues. Ln this treatise, we discuss the importance of the cell wall, which is plant-specific acid the most exterior organelle, in determining host-parasite specificity.

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：AMER PHYTOPATHOLOGICAL SOC  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：AMER PHYTOPATHOLOGICAL SOC  

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記述言語：英語   出版者・発行元：The Phytopathological Society of Japan  

エンドウ褐紋病菌のサプレッサーは宿主エンドウの原形質膜ATPase活性を抑制する。本報告では,可溶化・部分精製したエンドウ原形質膜ATPaseをリボソームに再構成し,ATPaseとプロトンポンプ活性に対するエリシターとサプレッサーの影響について調べた。再構成膜におけるプロトンポンプ活性はATPとMg²⁺に依存し,ATPaseの阻害剤で抑制されることからATPase依存性であることが推察できた。また,プロトンの勾配はプロトンイオノフォアやNH₄Clの添加で打ち消された。本活性に対するエリシターとサプレッサーの影響を調べたところ,エリシターは全く影響を及ぼさなかったが,サプレッサーは濃度依存的に活性を抑制した。さらに,ホスファチジルイノシトール2リン酸は本活性を上昇させたが,その作用点はサプレッサーの作用点とは異なることが示唆された。これらの結果から,エンドウ褐紋病菌はサプレッサーを分泌し,エンドウ細胞におけるホメオスタシスを攪乱することにより抵抗反応を抑制し,感染に成功するものと考察した。

DOI： 10.3186/jjphytopath.61.369

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：OXFORD UNIV PRESS  

Methyl jasmonate inhibited the harpin-induced defense responses such as cell death, H2O2 generation and gene expression encoding phenylalanine ammonia-lyase in tobacco suspension cultured BY-2 cells, These results suggest that MeJA may act as an endogenous suppressor for plant defense response including hypersensitive reaction.

DOI： 10.1093/pcp/pce056

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総ページ数：333   記述言語：日本語

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記述言語：英語   掲載種別：書評論文，書評，文献紹介等  

In 1994, Oku reported that plant pathogens, mainly fungal pathogens, require three essential abilities to infect plants: to enter plants, to overcome host resistance, and to evoke disease. Because the infectious process of phytopathogenic bacteria differs from that of fungal pathogens, we have attempted to characterize pathogenicity, the ability of a pathogen to cause disease, using the phytopathogenic bacterium Pseudomonas syringae as a representative pathogen. To establish infection and incite disease development, bacteria first have to enter a plant. This process requires flagella- and type IV pili-mediated motility, and active taxis is probably necessary for effective infection. After bacteria enter a plant's apoplastic spaces, they need to overcome host plant resistance. To do this, they secrete a wide variety of hypersensitive response and pathogenicity (Hrp) effector proteins into the plant cytoplasm to interfere with pathogen/microbe-associated molecular pattern- and effector-triggered immunity, produce phytohormones and/or phytotoxins to suppress plant defense responses and extracellular polysaccharides to prevent access by antibiotics and to chelate Ca2+, and activate the multidrug resistance efflux pump to extrude antimicrobial compounds for successful colonization. Furthermore, to evoke disease, bacteria produce toxins and Hrp effectors that compromise a plant's homeostasis and injure plant cells. The expression of these virulence factors depends on the infection processes and environmental conditions. Thus, the expression and function of virulence factors interact with each other, creating complex networks in the regulation of bacterial virulence-related genes. © 2013 The Phytopathological Society of Japan and Springer Japan.

DOI： 10.1007/s10327-013-0452-8

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記述言語：英語   掲載種別：研究発表ペーパー・要旨（国際会議）   出版者・発行元：AMER PHYTOPATHOLOGICAL SOC  

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担当区分：最終著者,　責任著者   記述言語：英語  

DOI： 10.1128/jb.00689-09

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記述言語：英語   出版者・発行元：SPRINGER TOKYO  

To initiate defense responses against invasion of pathogenic organisms, animals and plants must recognize microbe-associated molecular patterns (MAMPs). In this study, the elicitor activity of bacterial DNA on the model plant Arabidopsis thaliana was examined. EcoRI-digested plasmid DNA induced defense responses such as generation of reactive oxygen species and deposition of callose, whereas SmaI- and HapII-digested plasmid DNA and EcoRI-digested herring DNA did not remarkably induce these responses. Further, methylation of the CpG sequence of plasmid DNA and Escherichia coli DNA reduced the level of the defense responses. The endocytosis inhibitors wortmannin and amantadine significantly inhibited DNA-induced defense responses. These results suggest that non-methylated CpG DNA, as a MAMP, induced defense responses in Arabidopsis and that non-methylated DNA seems to be translocated into the cytoplasm by endocytosis.

DOI： 10.1007/s10327-009-0162-4

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担当区分：最終著者,　責任著者   記述言語：英語   出版者・発行元：Springer Science and Business Media LLC  

To initiate defense responses against invasion of pathogenic organisms, animals and plants must recognize microbe-associated molecular patterns (MAMPs). In this study, the elicitor activity of bacterial DNA on the model plant Arabidopsis thaliana was examined. EcoRI-digested plasmid DNA induced defense responses such as generation of reactive oxygen species and deposition of callose, whereas SmaI- and HapII-digested plasmid DNA and EcoRI-digested herring DNA did not remarkably induce these responses. Further, methylation of the CpG sequence of plasmid DNA and Escherichia coli DNA reduced the level of the defense responses. The endocytosis inhibitors wortmannin and amantadine significantly inhibited DNA-induced defense responses. These results suggest that non-methylated CpG DNA, as a MAMP, induced defense responses in Arabidopsis and that non-methylated DNA seems to be translocated into the cytoplasm by endocytosis.

DOI： 10.1007/s10327-009-0162-4

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その他リンク： http://link.springer.com/article/10.1007/s10327-009-0162-4/fulltext.html

記述言語：英語   出版者・発行元：Oxford University Press (OUP)  

The cell wall protein fraction (CWP) is purified from the non-pathogenic biocontrol agent Pythium oligandrum and is composed of two glycoproteins (POD-1 and POD-2), which are structurally similar to class III elicitins. In tomato plants treated with CWP, jasmonic acid (JA)- and ethylene (ET)-dependent signaling pathways are activated, and resistance to Ralstonia solanaceraum is enhanced. To dissect CWP-induced defense mechanisms, we investigated defense gene expression and resistance to bacterial pathogens in Arabidopsis thaliana ecotype Col-0 treated with CWP. When the leaves of Col-0 were infiltrated with CWP, neither visible necrosis nor salicylic acid (SA)-responsive gene (PR-1 and PR-5) expression was induced. In contrast, JA-responsive gene (PDF1.2 and JR2) expression was up-regulated and the resistance to R. solanaceraum and Pseudomonas syringae pv. tomato DC3000 was enhanced in response to CWP. Such CWP-induced defense responses were completely compromised in CWP-treated coi1-1 and jar1-1 mutants with an impaired JA signaling pathway. The induction of defense-related gene expression after CWP treatment was partially compromised in ET-insensitive ein2-1 mutants, but not in SA signaling mutants or nahG transgenic plants. Global gene expression analysis using cDNA array also suggested that several other JA- and ET-responsive genes, but not SA-responsive genes, were up-regulated in response to CWP. Further analysis of CWP-induced defense responses using another eight mutants with impaired defense signaling pathways indicated that, interestingly, the induction of JA-responsive gene expression and enhanced resistance to two bacterial pathogens in response to CWP were completely compromised in rar1-1, rar1-21, sgt1a-1, sgt1b (edm1) and npr1-1 mutants. Thus, the CWP-induced defense system appears to be regulated by JA-mediated and SGT1-, RAR1- and NPR1-dependent signaling pathways.

DOI： 10.1093/pcp/pcp044

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記述言語：英語   出版者・発行元：OXFORD UNIV PRESS  

The cell wall protein fraction (CWP) is purified from the non-pathogenic biocontrol agent Pythium oligandrum and is composed of two glycoproteins (POD-1 and POD-2), which are structurally similar to class III elicitins. In tomato plants treated with CWP, jasmonic acid (JA)- and ethylene (ET)-dependent signaling pathways are activated, and resistance to Ralstonia solanaceraum is enhanced. To dissect CWP-induced defense mechanisms, we investigated defense gene expression and resistance to bacterial pathogens in Arabidopsis thaliana ecotype Col-0 treated with CWP. When the leaves of Col-0 were infiltrated with CWP, neither visible necrosis nor salicylic acid (SA)-responsive gene (PR-1 and PR-5) expression was induced. In contrast, JA-responsive gene (PDF1.2 and JR2) expression was up-regulated and the resistance to R. solanaceraum and Pseudomonas syringae pv. tomato DC3000 was enhanced in response to CWP. Such CWP-induced defense responses were completely compromised in CWP-treated coi1-1 and jar1-1 mutants with an impaired JA signaling pathway. The induction of defense-related gene expression after CWP treatment was partially compromised in ET-insensitive ein2-1 mutants, but not in SA signaling mutants or nahG transgenic plants. Global gene expression analysis using cDNA array also suggested that several other JA- and ET-responsive genes, but not SA-responsive genes, were up-regulated in response to CWP. Further analysis of CWP-induced defense responses using another eight mutants with impaired defense signaling pathways indicated that, interestingly, the induction of JA-responsive gene expression and enhanced resistance to two bacterial pathogens in response to CWP were completely compromised in rar1-1, rar1-21, sgt1a-1, sgt1b (edm1) and npr1-1 mutants. Thus, the CWP-induced defense system appears to be regulated by JA-mediated and SGT1-, RAR1- and NPR1-dependent signaling pathways.

DOI： 10.1093/pcp/pcp044

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記述言語：英語  

DOI： 10.1094/MPMI-21-11-1398

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記述言語：英語   出版者・発行元：AMER PHYTOPATHOLOGICAL SOC  

A coiled coil-nucleotide binding site-leucine rich repeat-type resistance gene, RCY1, confers resistance to a yellow strain of Cucumber mosaic virus, CMV(Y), in Arabidopsis thaliana ecotype C24. Resistance to CMV(Y) in C24 is accompanied by a hypersensitive response (HR) that is characterized by the development of necrotic local lesions at the primary infection sites. To further study the HR and resistance to CMV(Y) in ecotype Col-0, which is susceptible to CMV(Y), Col-0 were transformed with RCY1. Systemic spread of CMV(Y) was completely suppressed in RCY1-transformed Col-0 (Col::pRCY1 lines 2 to 6), whereas virulent strain CMV(B2) spread and multiplied systemically in these transgenic lines similar to that in wild-type Col-0. Interestingly, the resistant phenotype of Col:pRCY1 varied among the lines. In lines 3 and 6, in which levels of RCY1 transcript were similar to that in wild-type C24, the HR and resistance to CMV(Y) was induced. Line 4, which expresses moderately elevated levels of RCY1 transcript, exhibited moderately enhanced resistance compared with that in C24 or line 3. In contrast, lines 2 and 5, which highly overexpress the RCY1 gene, did not exhibit either visible lesions or a micro-HR on the inoculated leaves. Moreover, virus coat protein was not detected in either inoculated or noninoculated upper leaves of these two lines, suggesting that extreme resistance (ER) to CMV(Y) was induced by high levels of expression of RCY1. Furthermore, in transgenic lines expressing hemagglutinin (HA) epitope-tagged RCY1 (Col::pRCY1-HA), high levels of accumulation of RCY1-HA protein were also correlated with the ER phenotype. Global gene expression analysis in line 2, which highly overexpresses RCY1, indicated that expression of several defense-related genes were constitutively elevated compared with wild-type Col-0. Despite this, line 2 did not have enhanced resistance to other avirulent and virulent pathogens. Take together, constitutive accumulation of high levels of RCY1 protein appears to regulate the strength of RCY1-conferred resistance in a gene-for-gene manner and implies that ER and HR-associated resistance differ only in the strength of resistance.

DOI： 10.1094/MPMI-21-11-1398

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担当区分：最終著者   記述言語：英語   出版者・発行元：AMER PHYTOPATHOLOGICAL SOC  

A nonpathogenic strain of Agrobacterium vitis VAR03-1 was tested as a biological control agent for crown gall of grapevine (Vitis vinifera). When roots of grapevine, rose (Rose multiflora), and tomato (Lycopersicon esculentum) were soaked in a cell suspension of antagonists before planting in soil infested with tumorigenic A. vitis, A. rhizogenes, and A. tumefaciens, respectively, treatment with VAR03-1 significantly reduced the number of plants with tumors and disease severity in the three plant species. The inhibitory effects of treatment with VAR03-1 and the nonpathogenic A. rhizogenes strain K84 on crown gall of rose and tomato were almost identical, and the inhibitory effect of VAR03-1 on grapevine was superior to that of K84. Moreover, VAR03-1 greatly controlled crown gall of grapevine due to tumorigenic A. vitis in the field. VAR03-1 established populations averaging 10(6) colony forming units (CFU)/g of root in the rhizosphere of grapevine and persisted on roots for 2 years. VAR03-1 was bacteriocinogenic, producing a halo of inhibition against those three species of Agrobacterium. This is the first report that a nonpathogenic strain, VAR03-1, can effectively control crown gall caused by tumorigenic A. vitis, A. rhizogenes, and A. tumefaciens.

DOI： 10.1094/PHYTO-98-11-1218

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記述言語：英語   出版者・発行元：AMER PHYTOPATHOLOGICAL SOC  

A nonpathogenic strain of Agrobacterium vitis VAR03-1 was tested as a biological control agent for crown gall of grapevine (Vitis vinifera). When roots of grapevine, rose (Rose multiflora), and tomato (Lycopersicon esculentum) were soaked in a cell suspension of antagonists before planting in soil infested with tumorigenic A. vitis, A. rhizogenes, and A. tumefaciens, respectively, treatment with VAR03-1 significantly reduced the number of plants with tumors and disease severity in the three plant species. The inhibitory effects of treatment with VAR03-1 and the nonpathogenic A. rhizogenes strain K84 on crown gall of rose and tomato were almost identical, and the inhibitory effect of VAR03-1 on grapevine was superior to that of K84. Moreover, VAR03-1 greatly controlled crown gall of grapevine due to tumorigenic A. vitis in the field. VAR03-1 established populations averaging 10(6) colony forming units (CFU)/g of root in the rhizosphere of grapevine and persisted on roots for 2 years. VAR03-1 was bacteriocinogenic, producing a halo of inhibition against those three species of Agrobacterium. This is the first report that a nonpathogenic strain, VAR03-1, can effectively control crown gall caused by tumorigenic A. vitis, A. rhizogenes, and A. tumefaciens.

DOI： 10.1094/PHYTO-98-11-1218

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担当区分：最終著者,　責任著者   記述言語：英語   出版者・発行元：AMER PHYTOPATHOLOGICAL SOC  

Flagellin proteins derived from Pseudomonas syringae pv. tabaci 6605 and flg22(Pa) (QRLSTGSRINSAKDDAAGLQIA), one of the microbe-associated molecular patterns (MAMP) in bacterial flagellin, induce cell death and growth inhibition in Arabidopsis thaliana. To examine the importance of aspartic acid (D) at position 43 from the N-terminus of a flagellin in its elicitor activity, D43 was replaced with valine (V) and alanine (A) in P. syringae pv. tabaci flagellin and flg22(Pta). The abilities of flagellins from P syringae pv. tabaci D43V and D43A to induce cell death and growth inhibition were reduced, whereas the abilities of flg22(Pta)D43V and flg22(Pta)D43A were abolished. These results indicate that D43 is important for elicitor activity in P. syringae pv. tabaci. When tobacco plants were inoculated with each bacterium by the spray method, both P. syringae pv. tabaci D43V and D43A mutants had remarkably reduced ability to cause disease symptoms. Both mutants had reduced or no swimming and swarming motilities and adhesion ability. In P. syringae pv. tabaci D43V, little flagellin protein was detected and few flagella were observed by electron microscopy. These results indicate that mutant flagella are unstable and that flagellar motility is impaired. Thus, the amino acid residue required for MAMP activity is important for the intrinsic flagellar function.

DOI： 10.1094/MPMI-21-9-1165

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記述言語：英語   出版者・発行元：AMER PHYTOPATHOLOGICAL SOC  

Flagellin proteins derived from Pseudomonas syringae pv. tabaci 6605 and flg22(Pa) (QRLSTGSRINSAKDDAAGLQIA), one of the microbe-associated molecular patterns (MAMP) in bacterial flagellin, induce cell death and growth inhibition in Arabidopsis thaliana. To examine the importance of aspartic acid (D) at position 43 from the N-terminus of a flagellin in its elicitor activity, D43 was replaced with valine (V) and alanine (A) in P. syringae pv. tabaci flagellin and flg22(Pta). The abilities of flagellins from P syringae pv. tabaci D43V and D43A to induce cell death and growth inhibition were reduced, whereas the abilities of flg22(Pta)D43V and flg22(Pta)D43A were abolished. These results indicate that D43 is important for elicitor activity in P. syringae pv. tabaci. When tobacco plants were inoculated with each bacterium by the spray method, both P. syringae pv. tabaci D43V and D43A mutants had remarkably reduced ability to cause disease symptoms. Both mutants had reduced or no swimming and swarming motilities and adhesion ability. In P. syringae pv. tabaci D43V, little flagellin protein was detected and few flagella were observed by electron microscopy. These results indicate that mutant flagella are unstable and that flagellar motility is impaired. Thus, the amino acid residue required for MAMP activity is important for the intrinsic flagellar function.

DOI： 10.1094/MPMI-21-9-1165

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記述言語：日本語   出版者・発行元：日本植物病理学会  

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記述言語：日本語   出版者・発行元：日本植物病理学会  

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記述言語：日本語   出版者・発行元：日本植物病理学会  

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担当区分：最終著者   記述言語：英語   出版者・発行元：WILEY-BLACKWELL  

Twenty-eight strains of Agrobacterium vitis, including both tumorigenic and nonpathogenic phenotypes involving 26 isolated in Japan and strains NCPPB 3554(T) and NCPPB 2562 isolated in Australia and Greece, respectively, were characterized by means of a slide agglutination test (SAT) using antisera prepared against somatic antigens. Phylogenetic analyses were also carried out, using the results of repetitive sequence-based polymerase chain reaction and the partial nucleotide sequences of pyrG, recA and rpoD. The A. vitis strains separated into four serogroups (A to D) based on the SAT reactivity. The phylogenetic analyses showed A. vitis strains separated into four tumorigenic groups (A to D) and one nonpathogenic group (E). Serogroups A to C corresponded exactly to genetic groups A to C, respectively, whereas serogroup D further divided into two distinct genetic groups, D and E. Genetic group E was isolated in Okayama Prefecture, Japan, and all strains of it have been found to coexist with tumorigenic strains belonging to the other groups within the same galled grapevine tissues. These results suggest that A. vitis strains are genetically heterogeneous and can be separated into several genetic groups. The differences between the nucleotide sequences of pyrG, recA and rpoD of the genetic groups will enable the development of a simple and convenient monitoring method, which will increase understanding of the dynamics of each genetic group of A. vitis in the natural environment.

DOI： 10.1111/j.1365-3059.2008.01829.x

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記述言語：英語   出版者・発行元：WILEY-BLACKWELL  

Twenty-eight strains of Agrobacterium vitis, including both tumorigenic and nonpathogenic phenotypes involving 26 isolated in Japan and strains NCPPB 3554(T) and NCPPB 2562 isolated in Australia and Greece, respectively, were characterized by means of a slide agglutination test (SAT) using antisera prepared against somatic antigens. Phylogenetic analyses were also carried out, using the results of repetitive sequence-based polymerase chain reaction and the partial nucleotide sequences of pyrG, recA and rpoD. The A. vitis strains separated into four serogroups (A to D) based on the SAT reactivity. The phylogenetic analyses showed A. vitis strains separated into four tumorigenic groups (A to D) and one nonpathogenic group (E). Serogroups A to C corresponded exactly to genetic groups A to C, respectively, whereas serogroup D further divided into two distinct genetic groups, D and E. Genetic group E was isolated in Okayama Prefecture, Japan, and all strains of it have been found to coexist with tumorigenic strains belonging to the other groups within the same galled grapevine tissues. These results suggest that A. vitis strains are genetically heterogeneous and can be separated into several genetic groups. The differences between the nucleotide sequences of pyrG, recA and rpoD of the genetic groups will enable the development of a simple and convenient monitoring method, which will increase understanding of the dynamics of each genetic group of A. vitis in the natural environment.

DOI： 10.1111/j.1365-3059.2008.01829.x

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担当区分：最終著者,　責任著者   記述言語：英語   出版者・発行元：ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD  

Polyphosphate kinase (PPK), encoded by the ppk gene, is a principal enzyme responsible for synthesis of inorganic polyphosphate (poly P) from ATP in many Gram-negative bacteria. In order to elucidate the functions of poly P in Pseudomonas syringae pv. tabaci 6605, an in-frame deletion mutant of the ppk gene (Delta ppk) was constructed. The Delta ppk mutant did not accumulate poly P, whereas the wild-type strain accumulated a large quantity. The mutant had reduced swarming motility, even though it retains swimming motility like the parental strain. The mutant exhibited increased sensitivity to prolonged incubation and environmental stresses, such as heat shock and oxidative stress and reduced exopolysaccharide (EPS) production compared to the wild-type. Northern blot analysis revealed that expression of the rpoS gene, encoding the stationary phase sigma factor RpoS, was reduced in Delta ppk in the logarithmic phase, indicating that rpoS is regulated by the ppk gene. The poly P deficient mutant had significantly reduced ability to cause disease in its host tobacco plant and in planta growth of the mutant was also significantly reduced in host tobacco leaves as compared to the wild-type strain. Thus, our results suggest that poly P plays an important role in the virulence of P. syringae pv. tabaci 6605. (C) 2008 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.pmpp.2008.04.007

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記述言語：英語   出版者・発行元：ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD  

Polyphosphate kinase (PPK), encoded by the ppk gene, is a principal enzyme responsible for synthesis of inorganic polyphosphate (poly P) from ATP in many Gram-negative bacteria. In order to elucidate the functions of poly P in Pseudomonas syringae pv. tabaci 6605, an in-frame deletion mutant of the ppk gene (Delta ppk) was constructed. The Delta ppk mutant did not accumulate poly P, whereas the wild-type strain accumulated a large quantity. The mutant had reduced swarming motility, even though it retains swimming motility like the parental strain. The mutant exhibited increased sensitivity to prolonged incubation and environmental stresses, such as heat shock and oxidative stress and reduced exopolysaccharide (EPS) production compared to the wild-type. Northern blot analysis revealed that expression of the rpoS gene, encoding the stationary phase sigma factor RpoS, was reduced in Delta ppk in the logarithmic phase, indicating that rpoS is regulated by the ppk gene. The poly P deficient mutant had significantly reduced ability to cause disease in its host tobacco plant and in planta growth of the mutant was also significantly reduced in host tobacco leaves as compared to the wild-type strain. Thus, our results suggest that poly P plays an important role in the virulence of P. syringae pv. tabaci 6605. (C) 2008 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.pmpp.2008.04.007

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記述言語：英語   出版者・発行元：SPRINGER  

Pseudomonas syringae pv. tabaci 6605 causes wildfire disease on host tobacco plants. To investigate the regulatory mechanism of the expression of virulence, Gac two-Component system-defective mutants, Delta gacA and Delta gacS, and a double mutant, Delta gacA Delta gacS, were generated. These mutants produced smaller amounts of N-acyl homoserine lactones required for quorum sensing, had lost swarming motility, and had reduced expression of virulence-related hrp genes and the algT gene required for exopolysaccharide production. The ability of the mutants to cause disease symptoms in their host tobacco plant was remarkably reduced, while they retained the ability to induce hypersensitive reaction (HR) in the nonhost plants. These results indicated that the Gac two-component system of P. syringae pv. tabaci 6605 is indispensable for virulence on the host plant, but not for HR induction in the nonhost plants.

DOI： 10.1007/s00438-007-0309-y

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担当区分：最終著者,　責任著者   記述言語：英語   出版者・発行元：SPRINGER  

Pseudomonas syringae pv. tabaci 6605 causes wildfire disease on host tobacco plants. To investigate the regulatory mechanism of the expression of virulence, Gac two-Component system-defective mutants, Delta gacA and Delta gacS, and a double mutant, Delta gacA Delta gacS, were generated. These mutants produced smaller amounts of N-acyl homoserine lactones required for quorum sensing, had lost swarming motility, and had reduced expression of virulence-related hrp genes and the algT gene required for exopolysaccharide production. The ability of the mutants to cause disease symptoms in their host tobacco plant was remarkably reduced, while they retained the ability to induce hypersensitive reaction (HR) in the nonhost plants. These results indicated that the Gac two-component system of P. syringae pv. tabaci 6605 is indispensable for virulence on the host plant, but not for HR induction in the nonhost plants.

DOI： 10.1007/s00438-007-0309-y

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その他リンク： http://link.springer.com/article/10.1007/s00438-007-0309-y/fulltext.html

記述言語：英語   出版者・発行元：SPRINGER  

Flagellin, a component of the flagellar filament of Pseudomonas syringae pv. tabaci 6605 (Pta), induces hypersensitive reaction in its non-host Arabidopsis thaliana. We identified the WRKY41 gene, which belongs to a multigene family encoding WRKY plant-specific transcription factors, as one of the flagellin-inducible genes in A. thaliana. Expression of WRKY41 is induced by inoculation with the incompatible pathogen P. syringae pv. tomato DC3000 (Pto) possessing AvrRpt2 and the non-host pathogens Pta within 6-h after inoculation, but not by inoculation with the compatible Pto. Expression of WRKY41 was also induced by inoculation of A. thaliana with an hrp-type three secretion system (T3SS)-defective mutant of Pto, indicating that effectors produced by T3SS in the Pto wild-type suppress the activation of WRKY41. Arabidopsis overexpressing WRKY41 showed enhanced resistance to the Pto wild-type but increased susceptibility to Erwinia carotovora EC1. WRKY41-overexpressing Arabidopsis constitutively expresses the PR5 gene, but suppresses the methyl jasmonate-induced PDF1.2 gene expression. These results demonstrate that WRKY41 may be a key regulator in the cross talk of salicylic acid and jasmonic acid pathways.

DOI： 10.1007/s00438-007-0315-0

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担当区分：最終著者,　責任著者   記述言語：英語   出版者・発行元：SPRINGER  

Flagellin, a component of the flagellar filament of Pseudomonas syringae pv. tabaci 6605 (Pta), induces hypersensitive reaction in its non-host Arabidopsis thaliana. We identified the WRKY41 gene, which belongs to a multigene family encoding WRKY plant-specific transcription factors, as one of the flagellin-inducible genes in A. thaliana. Expression of WRKY41 is induced by inoculation with the incompatible pathogen P. syringae pv. tomato DC3000 (Pto) possessing AvrRpt2 and the non-host pathogens Pta within 6-h after inoculation, but not by inoculation with the compatible Pto. Expression of WRKY41 was also induced by inoculation of A. thaliana with an hrp-type three secretion system (T3SS)-defective mutant of Pto, indicating that effectors produced by T3SS in the Pto wild-type suppress the activation of WRKY41. Arabidopsis overexpressing WRKY41 showed enhanced resistance to the Pto wild-type but increased susceptibility to Erwinia carotovora EC1. WRKY41-overexpressing Arabidopsis constitutively expresses the PR5 gene, but suppresses the methyl jasmonate-induced PDF1.2 gene expression. These results demonstrate that WRKY41 may be a key regulator in the cross talk of salicylic acid and jasmonic acid pathways.

DOI： 10.1007/s00438-007-0315-0

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記述言語：日本語   出版者・発行元：日本植物病理学会  

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担当区分：最終著者,　責任著者   記述言語：英語   出版者・発行元：AMER SOC MICROBIOLOGY  

The role of flagellin glycosylation on motility was investigated in Pseudomonas syringae pv. tabaci. The swimming activity of glycosylation-defective mutants was prominently decreased in a highly viscous medium. The mutants showed differences in polymorphic transitions and in the bundle formation of flagella, indicating that glycosylation stabilizes the filament structure and lubricates the rotation of the bundle.

DOI： 10.1128/JB.01282-07

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記述言語：英語   出版者・発行元：AMER SOC MICROBIOLOGY  

The role of flagellin glycosylation on motility was investigated in Pseudomonas syringae pv. tabaci. The swimming activity of glycosylation-defective mutants was prominently decreased in a highly viscous medium. The mutants showed differences in polymorphic transitions and in the bundle formation of flagella, indicating that glycosylation stabilizes the filament structure and lubricates the rotation of the bundle.

DOI： 10.1128/JB.01282-07

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記述言語：英語   掲載種別：研究発表ペーパー・要旨（国際会議）   出版者・発行元：GENETICS SOC JAPAN  

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記述言語：英語   出版者・発行元：AMER SOC MICROBIOLOGY  

Flagellins from Pseudomonas syringae pv. glycinea race 4 and Pseudomonas syringae pv. tabaci 6605 have been found to be glycosylated. Glycosylation of flagellin is essential for bacterial virulence and is also involved in the determination of host specificity. Flagellin glycans from both pathovars were characterized, and common sites of glycosylation were identified on six serine residues (positions 143, 164, 176, 183, 193, and 201). The structure of the glycan at serine 201 (S201) of flagellin from each pathovar was determined by sugar composition analysis, mass spectrometry, and H-1 and C-13 nuclear magnetic resonance spectroscopy. These analyses showed that the S201 glycans from both pathovars were composed of a common unique trisaccharide consisting of two rhamnosyl (Rha) residues and one modified 4-amino-4,6-dideoxyglucosyl (Qui4N) residue, beta-D-Quip4N(3-hydroxy-1-oxobutyl)2Me-(1 -&gt; 3)-alpha-L-Rhap-(1 -&gt; 2)-alpha-L-Rhap. Furthermore, mass analysis suggests that the glycans on each of the six serine residues are composed of similar trisaccharide units. Determination of the enantiomeric ratio of Rha from the flagellin proteins showed that flagellin from P. syringae pv. tabaci 6605 consisted solely Of L-Rha, whereas P. syringae pv. glycinea race 4 flagellin contained both L-Rha and D-Rha at a molar ratio of about 4:1. Taking these findings together with those from our previous study, we conclude that these flagellin glycan structures may be important for the virulence and host specificity of P. syringae.

DOI： 10.1128/JB.00500-07

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記述言語：英語  

Flagellin in Pseudomonas syringae is a potent elicitor of defense responses including hypersensitive cell death in dicot plants. The oligopeptides flg22 consisting of 22 conserved amino acids near the N-terminus of flagellins is reported to induce plant defense responses. Because glycosylation of the central domain of flagellin affects its elicitor activity, we investigated whether any peptide sequence in addition to flg22 is required for flagellin-induced hypersensitive reaction. A study of recombinant flagellin polypeptides indicated that the N-terminal domain including the conserved flg22 is required for flagellin-induced hypersensitive cell death in Arabidopsis thaliana. © 2007 The Phytopathological Society of Japan and Springer.

DOI： 10.1007/s10327-007-0017-9

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記述言語：英語  

Flagellin in Pseudomonas syringae is a potent elicitor of defense responses including hypersensitive cell death in dicot plants. The oligopeptides flg22 consisting of 22 conserved amino acids near the N-terminus of flagellins is reported to induce plant defense responses. Because glycosylation of the central domain of flagellin affects its elicitor activity, we investigated whether any peptide sequence in addition to flg22 is required for flagellin-induced hypersensitive reaction. A study of recombinant flagellin polypeptides indicated that the N-terminal domain including the conserved flg22 is required for flagellin-induced hypersensitive cell death in Arabidopsis thaliana. © 2007 The Phytopathological Society of Japan and Springer.

DOI： 10.1007/s10327-007-0017-9

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記述言語：英語   出版者・発行元：BLACKWELL PUBLISHING  

Non-host resistance is the most general form of disease resistance in plants because it is effective against most phytopathogens. The importance of hypersensitive responses (HRs) in non-host resistance of Nicotiana species to the oomycete Phytophthora is clear. INF1 elicitin, an elicitor obtained from the late-blight pathogen Phytophthora infestans, is sufficient to induce a typical HR in Nicotiana species. The molecular mechanisms that underlie the non-host resistance component of plant defence responses have been investigated using differential-display polymerase chain reaction (PCR) in a model HR system between INF1 elicitin and tobacco BY-2 cells. Differential-display PCR has revealed that Cdc27B is down-regulated in tobacco BY- 2 cells after treatment with INF1 elicitin. Cdc27B is one of 13 essential components of the anaphase- promoting complex or cyclosome ( APC/ C)-type E3 ubiquitin ligase complex in yeast. This APC/C-type E3 ubiquitin ligase complex regulates G2-to-M phase transition of the cell cycle by proteolytic degradation. In this study, we investigated the roles of this gene, NbCdc27B, in plant defence responses using virus-induced gene silencing. Suppression of NbCdc27B in Nicotiana benthamiana plants induced defence responses and a gain of resistance to Colletotrichum lagenarium fungus. Elicitin-induced hypersensitive cell death (HCD) was inhibited mildly in plants silenced with tobacco rattle virus:: Cdc27B. Cdc27B could manage the signalling pathways of plant defence responses as a negative regulator without HCD.

DOI： 10.1111/J.1364-3703.2007.00397.X

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記述言語：英語   出版者・発行元：BLACKWELL PUBLISHING  

Non-host resistance is the most general form of disease resistance in plants because it is effective against most phytopathogens. The importance of hypersensitive responses (HRs) in non-host resistance of Nicotiana species to the oomycete Phytophthora is clear. INF1 elicitin, an elicitor obtained from the late-blight pathogen Phytophthora infestans, is sufficient to induce a typical HR in Nicotiana species. The molecular mechanisms that underlie the non-host resistance component of plant defence responses have been investigated using differential-display polymerase chain reaction (PCR) in a model HR system between INF1 elicitin and tobacco BY-2 cells. Differential-display PCR has revealed that Cdc27B is down-regulated in tobacco BY- 2 cells after treatment with INF1 elicitin. Cdc27B is one of 13 essential components of the anaphase- promoting complex or cyclosome ( APC/ C)-type E3 ubiquitin ligase complex in yeast. This APC/C-type E3 ubiquitin ligase complex regulates G2-to-M phase transition of the cell cycle by proteolytic degradation. In this study, we investigated the roles of this gene, NbCdc27B, in plant defence responses using virus-induced gene silencing. Suppression of NbCdc27B in Nicotiana benthamiana plants induced defence responses and a gain of resistance to Colletotrichum lagenarium fungus. Elicitin-induced hypersensitive cell death (HCD) was inhibited mildly in plants silenced with tobacco rattle virus:: Cdc27B. Cdc27B could manage the signalling pathways of plant defence responses as a negative regulator without HCD.

DOI： 10.1111/J.1364-3703.2007.00397.X

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記述言語：英語   出版者・発行元：INFORMA HEALTHCARE-TAYLOR & FRANCIS  

The inhibition of elicitor-induced plant defense responses by the protein kinase inhibitors K252a and staurosporine indicates that defense responses require protein phosphorylation. We isolated a cDNA clone encoding Nicotiana tabacum lectin-like receptor protein kinase 1 ( NtlecRK1), an elicitor-responsive gene; in tobacco bright yellow ( BY-2) cells by a differential display method. NtlecRK forms a gene family with at least three members in tobacco. All three NtlecRK genes potentially encode the N-terminal legume lectin domain, transmembrane domain and C-terminal Ser/Thr-type protein kinase domain. Green fluorescent protein ( GFP) fusion showed that the NtlecRK1 protein was located on the plasma membrane. In addition, NtlecRK1 and 3 were responsive to INF1 elicitin and the bacterial elicitor harpin. These results indicate that NtlecRKs are membrane-located protein kinases that are induced during defense responses in BY-2 cells.

DOI： 10.1080/10425170601060905

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記述言語：英語   出版者・発行元：INFORMA HEALTHCARE-TAYLOR & FRANCIS  

The inhibition of elicitor-induced plant defense responses by the protein kinase inhibitors K252a and staurosporine indicates that defense responses require protein phosphorylation. We isolated a cDNA clone encoding Nicotiana tabacum lectin-like receptor protein kinase 1 ( NtlecRK1), an elicitor-responsive gene; in tobacco bright yellow ( BY-2) cells by a differential display method. NtlecRK forms a gene family with at least three members in tobacco. All three NtlecRK genes potentially encode the N-terminal legume lectin domain, transmembrane domain and C-terminal Ser/Thr-type protein kinase domain. Green fluorescent protein ( GFP) fusion showed that the NtlecRK1 protein was located on the plasma membrane. In addition, NtlecRK1 and 3 were responsive to INF1 elicitin and the bacterial elicitor harpin. These results indicate that NtlecRKs are membrane-located protein kinases that are induced during defense responses in BY-2 cells.

DOI： 10.1080/10425170601060905

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担当区分：最終著者,　責任著者   記述言語：英語   出版者・発行元：AMER SOC MICROBIOLOGY  

Pseudomonas syringae pv. tabaci 6605 possesses a genetic region involved in flagellin glycosylation. This region is composed of three open reading frames: orf1, orf2, and orf3. Our previous study revealed that orf1 and orf2 encode glycosyltransferases; on the other hand, orf3 has no role in posttranslational modification of flagellin. Although the function of Orf3 remained unclear, an orf3 deletion mutant (Delta orf3 mutant) had reduced virulence on tobacco plants. Orf3 shows significant homology to a 3-oxoacyl-(acyl carrier protein) synthase III in the fatty acid elongation cycle. The Delta orf3 mutant had a significantly reduced ability to form acyl homoserine lactones (AHLs), which are quorum-sensing molecules, suggesting that Orf3 is required for AHL synthesis. In comparison with the wild-type strain, swarming motility, biosurfactant production, and tolerance to H2O2 and antibiotics were enhanced in the Delta orf3 mutant. A scanning electron micrograph of inoculated bacteria on the tobacco leaf surface revealed that there is little extracellular polymeric substance matrix surrounding the cells in the Delta orf3 mutant. The phenotypes of the Delta orf3 mutant and an AHL synthesis (Delta psyI) mutant were similar, although the mutant-specific characteristics were more extreme in the Delta orf3 mutant. The swarming motility of the Delta orf3 mutant was greater than that of the Delta psyI mutant. This was attributed to the synergistic effects of the overproduction of biosurfactants and/or alternative fatty acid metabolism in the Delta orf3 mutant. Furthermore, the amounts of iron and biosurfactant seem to be involved in biofilm development under quorum-sensing regulation in P. syringae pv. tabaci 6605.

DOI： 10.1128/JB.00763-06

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記述言語：英語   出版者・発行元：AMER SOC MICROBIOLOGY  

Pseudomonas syringae pv. tabaci 6605 possesses a genetic region involved in flagellin glycosylation. This region is composed of three open reading frames: orf1, orf2, and orf3. Our previous study revealed that orf1 and orf2 encode glycosyltransferases; on the other hand, orf3 has no role in posttranslational modification of flagellin. Although the function of Orf3 remained unclear, an orf3 deletion mutant (Delta orf3 mutant) had reduced virulence on tobacco plants. Orf3 shows significant homology to a 3-oxoacyl-(acyl carrier protein) synthase III in the fatty acid elongation cycle. The Delta orf3 mutant had a significantly reduced ability to form acyl homoserine lactones (AHLs), which are quorum-sensing molecules, suggesting that Orf3 is required for AHL synthesis. In comparison with the wild-type strain, swarming motility, biosurfactant production, and tolerance to H2O2 and antibiotics were enhanced in the Delta orf3 mutant. A scanning electron micrograph of inoculated bacteria on the tobacco leaf surface revealed that there is little extracellular polymeric substance matrix surrounding the cells in the Delta orf3 mutant. The phenotypes of the Delta orf3 mutant and an AHL synthesis (Delta psyI) mutant were similar, although the mutant-specific characteristics were more extreme in the Delta orf3 mutant. The swarming motility of the Delta orf3 mutant was greater than that of the Delta psyI mutant. This was attributed to the synergistic effects of the overproduction of biosurfactants and/or alternative fatty acid metabolism in the Delta orf3 mutant. Furthermore, the amounts of iron and biosurfactant seem to be involved in biofilm development under quorum-sensing regulation in P. syringae pv. tabaci 6605.

DOI： 10.1128/JB.00763-06

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記述言語：日本語  

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記述言語：英語  

We previously reported that the release of O2 - from isolated pea cell walls was enhanced by a 70-kDa glycoprotein elicitor but was suppressed by mucin-type glycopeptide suppressors (supprescins A and B) prepared from pycnospore germination fluid of Mycosphaerella pinodes, causal agent of Mycosphaerella blight of pea. Here, we show that superoxide dismutase (SOD) in the apoplast fluid/cell wall of pea seedlings responds to the fungal elicitor and suppressor molecules. In a pharmacological study and with internal amino acid sequencing, the apoplastic SOD in a pea cultivar Midoriusui was found to be a Cu/Zn type SOD. We cloned a full-length cDNA of the Cu/Zn-SOD and designated it as PsCu/Zn-SOD1. An increase in PsCu/Zn-SOD1 mRNA and the PsCu/Zn-SOD1 protein was induced by treatment with the elicitor more intensively than by wounding. Such induction by the elicitor or wounding, however, was inhibited by the concomitant presence of supprescins. The SOD activity of recombinant PsCu/Zn-SOD1 was regulated directly by these signal molecules in a manner similar to their effect on the SOD activity in the apoplastic fluid and in the cell wall-bound proteins. Based on these findings, we discuss a role for PsCu/Zn-SOD1 in the pea defense response. © 2006 The Phytopathological Society of Japan and Springer-Verlag.

DOI： 10.1007/s10327-006-0283-y

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記述言語：英語  

We previously reported that the release of O2 - from isolated pea cell walls was enhanced by a 70-kDa glycoprotein elicitor but was suppressed by mucin-type glycopeptide suppressors (supprescins A and B) prepared from pycnospore germination fluid of Mycosphaerella pinodes, causal agent of Mycosphaerella blight of pea. Here, we show that superoxide dismutase (SOD) in the apoplast fluid/cell wall of pea seedlings responds to the fungal elicitor and suppressor molecules. In a pharmacological study and with internal amino acid sequencing, the apoplastic SOD in a pea cultivar Midoriusui was found to be a Cu/Zn type SOD. We cloned a full-length cDNA of the Cu/Zn-SOD and designated it as PsCu/Zn-SOD1. An increase in PsCu/Zn-SOD1 mRNA and the PsCu/Zn-SOD1 protein was induced by treatment with the elicitor more intensively than by wounding. Such induction by the elicitor or wounding, however, was inhibited by the concomitant presence of supprescins. The SOD activity of recombinant PsCu/Zn-SOD1 was regulated directly by these signal molecules in a manner similar to their effect on the SOD activity in the apoplastic fluid and in the cell wall-bound proteins. Based on these findings, we discuss a role for PsCu/Zn-SOD1 in the pea defense response. © 2006 The Phytopathological Society of Japan and Springer-Verlag.

DOI： 10.1007/s10327-006-0283-y

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記述言語：英語  

In the plant cell wall of Pisum sativum seedlings, we found an NTPase (E.C. 3.6.1.5.) with ATP-hydrolyzing activity that was regulated by an elicitor and suppressors of defense from pea pathogen Mycosphaerella pinodes. The ATPase-rich fraction was purified from pea cell walls by NaCl solubilization, ammonium sulfate precipitation, and chromatography with an ATP-conjugated agarose column and an anion-exchange column. The specific activity of the final ATPase-rich fraction increased 600-fold over that of the initial NaCl-solubilized fraction. The purified ATPase-rich fraction also had peroxidase activity and generated superoxide, both of which were regulated by the M. pinodes elicitor and suppressor (supprescins). Active staining and Western blot analysis also showed that the ATPase was copurified along with peroxidases. In this fraction, a biotinylated elicitor and the supprescins were bound primarily and specifically to ca. 55-kDa protein (CWP-55) with an N-terminal amino acid sequence of QEEISSYAVVFDA. The cDNA clone of CWP-55 contained five ACR domains, which are conserved in the apyrases (NTPases), and the protein is identical to a pea NTPase cDNA (GenBank accession AB071369). Based on these results, we discuss a role for the plant cell wall in recognizing exogenous signal molecules. © The Phytopathological Society of Japan and Springer-Verlag 2006.

DOI： 10.1007/s10327-006-0278-8

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記述言語：英語  

Apyrases (E.C.3.6.1.5
NTP-NDPases) are distributed in the cytosol, nuclei, cytoskeleton, and on the surface of plant cells. Some may play an important role in signal transduction from exogenous stimuli. We previously found a protein of ca. 55-kDa (CWP-55) in an ATPase-rich fraction from the pea cell wall bound to the elicitor and supprescins (suppressors of defense) from pea pathogen Mycosphaerella pinodes. We cloned the cDNA of CWP-55 that coincided with PsAPY1, one of two NTPase clones in a pea cDNA library. An analysis with a green fluorescent protein fusion protein indicated that PsAPY1 was distributed in the cell wall, nucleus, and cytoplasm. The recombinant PsAPY1 expressed in Escherichia coli had ATP-hydrolyzing activity responsive not only to the elicitor and supprescins from the pea pathogen but also to other elicitors such as a bacterial harpin, a yeast extract, and a synthetic glycopeptide. Biotinylated fungal signal molecules were bound to the recombinant PsAPY1 specifically. Resonant mirror detection confirmed such binding characteristics of PsAPY1. Based on these results, we discuss the role of cell-wall-bound NTPases in recognizing and responding to microorganisms on the cell wall surface. © The Phytopathological Society of Japan and Springer-Verlag 2006.

DOI： 10.1007/s10327-006-0279-7

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記述言語：英語  

Apyrases (E.C.3.6.1.5
NTP-NDPases) are distributed in the cytosol, nuclei, cytoskeleton, and on the surface of plant cells. Some may play an important role in signal transduction from exogenous stimuli. We previously found a protein of ca. 55-kDa (CWP-55) in an ATPase-rich fraction from the pea cell wall bound to the elicitor and supprescins (suppressors of defense) from pea pathogen Mycosphaerella pinodes. We cloned the cDNA of CWP-55 that coincided with PsAPY1, one of two NTPase clones in a pea cDNA library. An analysis with a green fluorescent protein fusion protein indicated that PsAPY1 was distributed in the cell wall, nucleus, and cytoplasm. The recombinant PsAPY1 expressed in Escherichia coli had ATP-hydrolyzing activity responsive not only to the elicitor and supprescins from the pea pathogen but also to other elicitors such as a bacterial harpin, a yeast extract, and a synthetic glycopeptide. Biotinylated fungal signal molecules were bound to the recombinant PsAPY1 specifically. Resonant mirror detection confirmed such binding characteristics of PsAPY1. Based on these results, we discuss the role of cell-wall-bound NTPases in recognizing and responding to microorganisms on the cell wall surface. © The Phytopathological Society of Japan and Springer-Verlag 2006.

DOI： 10.1007/s10327-006-0279-7

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記述言語：英語  

In the plant cell wall of Pisum sativum seedlings, we found an NTPase (E.C. 3.6.1.5.) with ATP-hydrolyzing activity that was regulated by an elicitor and suppressors of defense from pea pathogen Mycosphaerella pinodes. The ATPase-rich fraction was purified from pea cell walls by NaCl solubilization, ammonium sulfate precipitation, and chromatography with an ATP-conjugated agarose column and an anion-exchange column. The specific activity of the final ATPase-rich fraction increased 600-fold over that of the initial NaCl-solubilized fraction. The purified ATPase-rich fraction also had peroxidase activity and generated superoxide, both of which were regulated by the M. pinodes elicitor and suppressor (supprescins). Active staining and Western blot analysis also showed that the ATPase was copurified along with peroxidases. In this fraction, a biotinylated elicitor and the supprescins were bound primarily and specifically to ca. 55-kDa protein (CWP-55) with an N-terminal amino acid sequence of QEEISSYAVVFDA. The cDNA clone of CWP-55 contained five ACR domains, which are conserved in the apyrases (NTPases), and the protein is identical to a pea NTPase cDNA (GenBank accession AB071369). Based on these results, we discuss a role for the plant cell wall in recognizing exogenous signal molecules. © The Phytopathological Society of Japan and Springer-Verlag 2006.

DOI： 10.1007/s10327-006-0278-8

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記述言語：英語  

Apyrases (NTPases) are associated with both compatible and incompatible interactions between plants and microorganisms. Previously we reported that the ATPase activities of cell-wall-bound apyrases of several leguminous plants, such as pea, cowpea, soybean, and kidney bean, were enhanced by a glycoprotein elicitor and were inhibited in a species-specific manner by mucin-type glycopeptide suppressors secreted from a pea pathogenic fungus, Mycosphaerella pinodes. In this study, we isolated two apyrase genes, VsNTPase1 and VsNTPase2, from a cDNA library of Vigna sinensis Endl. cv. Sanjakusasage. Based on phylogenetic analysis, VsNTPase1 may belong to a group that responds to environmental stimuli. In a transient assay using DNA bombardment, a fusion protein of green fluorescent protein (GFP) and the N-terminal putative signal sequence of VsNTPase1 was distributed in the nucleus, cytoplasm (cytoskeletal structure), and cell wall. On the other hand, a fusion protein of GFP and the N-terminal putative VsNTPase2-signal sequence was localized in the cytoplasm, especially in small particles (perhaps mitochondria). A recombinant VsNTPase1 expressed in Spodoptera frugiperda 21 cells responded directly to signal molecules from several phytopathogenic microorganisms. Here, we discuss the role of apyrases in recognizing and responding to exogenous signals. © The Phytopathological Society of Japan and Springer-Verlag 2006.

DOI： 10.1007/s10327-005-0267-3

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記述言語：英語   出版者・発行元：BLACKWELL PUBLISHING  

A glycosylation island is a genetic region required for glycosylation. The glycosylation island of flagellin in Pseudomonas syringae pv. tabaci 6605 consists of three orfs: orf1, orf2 and orf3. Orf1 and orf2 encode putative glycosyltransferases, and their deletion mutants, Delta orf1 and Delta orf2, exhibit deficient flagellin glycosylation or produce partially glycosylated flagellin respectively. Digestion of glycosylated flagellin from wild-type bacteria and non-glycosylated flagellin from Delta orf1 mutant using aspartic N-peptidase and subsequent HPLC analysis revealed candidate glycosylated amino acids. By generation of site-directed Ser/Ala-substituted mutants, all glycosylated amino acid residues were identified at positions 143, 164, 176, 183, 193 and 201. Matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectrometry (MS) analysis revealed that each glycan was about 540 Da. While all glycosylation-defective mutants retained swimming ability, swarming ability was reduced in the Delta orf1, Delta orf2 and Ser/Ala-substituted mutants. All glycosylation mutants were also found to be impaired in the ability to adhere to a polystyrene surface and in the ability to cause disease in tobacco. Based on the predicted tertiary structure of flagellin, S176 and S183 are expected to be located on most external surface of the flagellum. Thus the effect of Ala-substitution of these serines is stronger than that of other serines. These results suggest that glycosylation of flagellin in P. syringae pv. tabaci 6605 is required for bacterial virulence. It is also possible that glycosylation of flagellin may mask elicitor function of flagellin molecule.

DOI： 10.1111/j.1462-5822.2005.0674.x

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記述言語：英語  

When inorganic phosphate, a common and essential element for organisms, was applied endogenously, a rejection reaction and superoxide generation were induced in pea tissues but phytoalexin production was not. Phosphate-induced superoxide generation was sensitive to cycloheximide (CHX) and salicylhydroxamic acid (SHAM), indicating that part of the generation was dependent upon the expression of peroxidase gene(s). Peroxidases (POXs) are well known not only to scavenge hydrogen peroxide with phenolics but also to generate superoxide via NADH oxidation in the presence of p-coumaric acid and manganese ion. We cloned five pea POX cDNAs that are predicted to be located outside of the cells. The accumulation of five POX mRNAs, NTPase mRNA, and phenylalanine ammonia-lyase mRNA was measured by semiquantitative reverse transcription-polymerase chain reaction. The expression of the five POX genes was induced by a fungal elicitor. On the other hand, inorganic phosphate induced the accumulation of POX11, POX14, and POX21 mRNAs but not of POX13, POX29, and PsPAL1 mRNAs within 1-3∈h after treatment of pea seedlings. In view of these findings, we discuss inorganic phosphate as a signal transmitter inducing part of the plant defense responses. © The Phytopathological Society of Japan and Springer-Verlag 2006.

DOI： 10.1007/s10327-005-0261-9

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記述言語：英語  

When inorganic phosphate, a common and essential element for organisms, was applied endogenously, a rejection reaction and superoxide generation were induced in pea tissues but phytoalexin production was not. Phosphate-induced superoxide generation was sensitive to cycloheximide (CHX) and salicylhydroxamic acid (SHAM), indicating that part of the generation was dependent upon the expression of peroxidase gene(s). Peroxidases (POXs) are well known not only to scavenge hydrogen peroxide with phenolics but also to generate superoxide via NADH oxidation in the presence of p-coumaric acid and manganese ion. We cloned five pea POX cDNAs that are predicted to be located outside of the cells. The accumulation of five POX mRNAs, NTPase mRNA, and phenylalanine ammonia-lyase mRNA was measured by semiquantitative reverse transcription-polymerase chain reaction. The expression of the five POX genes was induced by a fungal elicitor. On the other hand, inorganic phosphate induced the accumulation of POX11, POX14, and POX21 mRNAs but not of POX13, POX29, and PsPAL1 mRNAs within 1-3∈h after treatment of pea seedlings. In view of these findings, we discuss inorganic phosphate as a signal transmitter inducing part of the plant defense responses. © The Phytopathological Society of Japan and Springer-Verlag 2006.

DOI： 10.1007/s10327-005-0261-9

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記述言語：英語  

Apyrases (NTPases) are associated with both compatible and incompatible interactions between plants and microorganisms. Previously we reported that the ATPase activities of cell-wall-bound apyrases of several leguminous plants, such as pea, cowpea, soybean, and kidney bean, were enhanced by a glycoprotein elicitor and were inhibited in a species-specific manner by mucin-type glycopeptide suppressors secreted from a pea pathogenic fungus, Mycosphaerella pinodes. In this study, we isolated two apyrase genes, VsNTPase1 and VsNTPase2, from a cDNA library of Vigna sinensis Endl. cv. Sanjakusasage. Based on phylogenetic analysis, VsNTPase1 may belong to a group that responds to environmental stimuli. In a transient assay using DNA bombardment, a fusion protein of green fluorescent protein (GFP) and the N-terminal putative signal sequence of VsNTPase1 was distributed in the nucleus, cytoplasm (cytoskeletal structure), and cell wall. On the other hand, a fusion protein of GFP and the N-terminal putative VsNTPase2-signal sequence was localized in the cytoplasm, especially in small particles (perhaps mitochondria). A recombinant VsNTPase1 expressed in Spodoptera frugiperda 21 cells responded directly to signal molecules from several phytopathogenic microorganisms. Here, we discuss the role of apyrases in recognizing and responding to exogenous signals. © The Phytopathological Society of Japan and Springer-Verlag 2006.

DOI： 10.1007/s10327-005-0267-3

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記述言語：英語   掲載種別：研究発表ペーパー・要旨（国際会議）   出版者・発行元：AMER PHYTOPATHOLOGICAL SOC  

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記述言語：日本語   出版者・発行元：Japan Society for Bioscience, Biotechnology, and Agrochemistry  

DOI： 10.1271/kagakutoseibutsu1962.44.556

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その他リンク： https://jlc.jst.go.jp/DN/JALC/00283065642?from=CiNii

J-GLOBAL

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記述言語：日本語   出版者・発行元：日本植物病理学会  

CiNii Article

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記述言語：英語  

We have previously shown that flagellin of Pseudomonas syringae pv. tabaci is an elicitor that induces a hypersensitive reaction (HR) in nonhost tomato cells. Flagellin is the major HR elicitor produced by this pathogen, as shown by the inability of a flagellin-defective mutant, ΔfliC, to induce HR. Also, a ΔfliD mutant that secretes large amounts of monomer flagellins induces a strong HR in tomato. In this study, the possible involvement of an Hrp type III secretion system (TTSS) in flagellin-induced HR was investigated using flagella-defective mutants or Hrp TTSS-defective mutants. The hrcC gene encodes HrcC protein, which is required for Hrp pilus formation in the outer membrane. An hrcC mutation, introduced into the wild-type, ΔfliC, and ΔfliD mutants of P. syringae pv. tabaci did not affect swimming motility or flagellin secretion, whereas all ΔhrcC, ΔfliC, and ΔfliD mutants lost the ability to cause disease on host tobacco leaves. However, the ΔhrcC mutant and the ΔfliD/ΔhrcC double mutant were still able to induce HR cell death, expression of one of the defense-related genes hsr203J, and the generation of hydrogen peroxide in nonhost tomato cells. Thus, flagellin is required for both pathogenicity in host tobacco and HR in nonhost tomato. On the other hand, hrp TTSS is necessary for pathogenicity on host tobacco but is not indispensable to induce HR in nonhost tomato. These results clearly show that flagellin-induced HR is hrp-independent in tomato. © The Phytopathological Society of Japan and Springer-Verlag 2005.

DOI： 10.1007/s10327-005-0200-9

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記述言語：英語  

Flagellin, an essential component of the bacterial flagellar filament, is capable of inducing a hypersensitive response (HR), including cell death, in a nonhost plant. A flagellin-defective mutant (ΔfliC) of Pseudomonas syringae pv. tabaci lacks both the flagellar filament and motility, whereas a flagellin-glycosylation-defective mutant (Δorf1) retains the flagellar filament but lacks the glycosyl modification of flagellin protein. To investigate the role of flagellin protein and its glycosylation in the interaction with its nonhost Arabidopsis thaliana, we analyzed plant responses after inoculation with these bacteria. Inoculation with wild-type P. syringae pv. tabaci induced HR, with the generation of reactive oxygen species and cell death. In contrast, inoculation with either ΔfliC or Δorf1 mutant induced a low level of HR, and inoculated leaves developed a disease-like yellowing. These mutant bacteria multiplied better than the wild-type bacteria in A. thaliana. These results indicate that A. thaliana expresses a defense reaction in response to the bacterial flagellin with its glycosyl structure. © The Phytopathological Society of Japan and Springer-Verlag 2005.

DOI： 10.1007/s10327-005-0201-8

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記述言語：英語  

DOI： 10.1007/s10327-005-0201-8

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記述言語：英語  

INF1 elicitin, a proteinaceous elicitor produced by Phytophthora infestans, induces a hypersensitive response in tobacco BY-2 cells. In response to elicitin, tobacco cells produce both reactive oxygen species (ROS) and ethylene (ET). To investigate the regulation of elicitin-induced ET production, we pharmacologically analyzed the effects of several chemicals on ET production. Inhibitors of ROS generation or ROS chelators efficiently inhibited ET production, whereas simultaneous treatment of a superoxide anion-generating system with salicylhydroxamic acid recovered ET production. In an in vitro experiment, superoxide anion was necessary and sufficient for conversion of 1-aminocyclopropane-1-carboxylate (ACC) to ET because ET was produced from ACC solely in the presence of the superoxide-generating chemical KO2. ET production was also inhibited by lipoxygenase (LOX) inhibitors, indicating a possible involvement of LOX-mediated generation of superoxide anion and ET production itself. Furthermore, elicitin-induced ET production was completely inhibited by the protein synthesis inhibitor cycloheximide but recovered after exogenous application of ACC, indicating that de novo protein synthesis is required for ACC accumulation, leading to ET production. We also investigated the effects of several phytohormones on elicitor-induced ET production and discuss their role in the defense response. © The Phytopathological Society of Japan and Springer-Verlag 2005.

DOI： 10.1007/s10327-005-0197-0

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記述言語：英語  

INF1 elicitin, a proteinaceous elicitor produced by Phytophthora infestans, induces a hypersensitive response in tobacco BY-2 cells. In response to elicitin, tobacco cells produce both reactive oxygen species (ROS) and ethylene (ET). To investigate the regulation of elicitin-induced ET production, we pharmacologically analyzed the effects of several chemicals on ET production. Inhibitors of ROS generation or ROS chelators efficiently inhibited ET production, whereas simultaneous treatment of a superoxide anion-generating system with salicylhydroxamic acid recovered ET production. In an in vitro experiment, superoxide anion was necessary and sufficient for conversion of 1-aminocyclopropane-1-carboxylate (ACC) to ET because ET was produced from ACC solely in the presence of the superoxide-generating chemical KO2. ET production was also inhibited by lipoxygenase (LOX) inhibitors, indicating a possible involvement of LOX-mediated generation of superoxide anion and ET production itself. Furthermore, elicitin-induced ET production was completely inhibited by the protein synthesis inhibitor cycloheximide but recovered after exogenous application of ACC, indicating that de novo protein synthesis is required for ACC accumulation, leading to ET production. We also investigated the effects of several phytohormones on elicitor-induced ET production and discuss their role in the defense response. © The Phytopathological Society of Japan and Springer-Verlag 2005.

DOI： 10.1007/s10327-005-0197-0

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記述言語：英語  

We have previously shown that flagellin of Pseudomonas syringae pv. tabaci is an elicitor that induces a hypersensitive reaction (HR) in nonhost tomato cells. Flagellin is the major HR elicitor produced by this pathogen, as shown by the inability of a flagellin-defective mutant, ΔfliC, to induce HR. Also, a ΔfliD mutant that secretes large amounts of monomer flagellins induces a strong HR in tomato. In this study, the possible involvement of an Hrp type III secretion system (TTSS) in flagellin-induced HR was investigated using flagella-defective mutants or Hrp TTSS-defective mutants. The hrcC gene encodes HrcC protein, which is required for Hrp pilus formation in the outer membrane. An hrcC mutation, introduced into the wild-type, ΔfliC, and ΔfliD mutants of P. syringae pv. tabaci did not affect swimming motility or flagellin secretion, whereas all ΔhrcC, ΔfliC, and ΔfliD mutants lost the ability to cause disease on host tobacco leaves. However, the ΔhrcC mutant and the ΔfliD/ΔhrcC double mutant were still able to induce HR cell death, expression of one of the defense-related genes hsr203J, and the generation of hydrogen peroxide in nonhost tomato cells. Thus, flagellin is required for both pathogenicity in host tobacco and HR in nonhost tomato. On the other hand, hrp TTSS is necessary for pathogenicity on host tobacco but is not indispensable to induce HR in nonhost tomato. These results clearly show that flagellin-induced HR is hrp-independent in tomato. © The Phytopathological Society of Japan and Springer-Verlag 2005.

DOI： 10.1007/s10327-005-0200-9

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記述言語：英語  

Mycosphaerella blight, caused by Mycosphaerella pinodes, is one of the major diseases of cultivated pea (Pisum sativum L.). To isolate the genes that are up- and down-regulated during spore germination, suppression subtraction hybridization (SSH) was performed between ungerminated and germinated spores. The 232 and 128 clones from forward and reverse libraries, respectively, were collected, sequenced, and analyzed with a BLASTX homology search. About 95% of the 32 selected clones were expressed during spore germination on a paper sheet and during infection of pea leaves. We discuss the applicability of the SSH libraries for analyzing M. pinodes genes involved in the early stage of infection. © The Phytopathological Society of Japan and Springer-Verlag 2005.

DOI： 10.1007/s10327-005-0185-4

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記述言語：日本語  

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記述言語：英語  

Lycopersicon esculentum cultivar Micro-Tom is a miniature tomato with many advantages for studies of the molecular biology and physiology of plants. To evaluate the suitability of Micro-Tom as a host plant for the study of pathogenesis, Micro-Tom plants were inoculated with 16 well-known fungal, bacterial, and viral pathogens of tomato. Athelia rolfsii, Botryotinia fuckeliana, Oidium sp., Phytophthora infestans, and Sclerotinia sclerotiorum caused typical symptoms and sporulated abundantly on Micro-Tom. Micro-Tom was resistant to Alternaria alternata, Corynespora cassiicola, and Fusarium oxysporum. When Micro-Tom was inoculated with 17 isolates of Ralstonia solanacearum, many isolates induced wilt symptoms. Agrobacterium tumefaciens also was pathogenic, causing crown galls on stem tissue after needle prick inoculation. In Micro-Tom sprayed with Pseudomonas syringae pv. tomato, P. s. pv. tabaci, or P. s. pv. glycinea, bacterial populations did not increase, and yellow lesions appeared only on leaves sprayed with P. s. pv. tomato. Tomato mosaic virus, Tomato aspermy virus, and Cucumber mosaic virus systemically infected Micro-Tom, which developed symptoms characteristic of other cultivars of tomato after infection with the respective virus. These results indicated that Micro-Tom was generally susceptible to most of the important tomato pathogens and developed typical symptoms, whereas certain pathogens were restricted by either hypersensitive resistance or nonhost resistance on Micro-Tom. Therefore, an assortment of Micro-Tom-pathogen systems should provide excellent models for studying the mechanism of susceptible and resistant interactions between plants and pathogens. © The Phytopathological Society of Japan and Springer-Verlag 2005.

DOI： 10.1007/s10327-004-0168-x

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記述言語：英語  

Lycopersicon esculentum cultivar Micro-Tom is a miniature tomato with many advantages for studies of the molecular biology and physiology of plants. To evaluate the suitability of Micro-Tom as a host plant for the study of pathogenesis, Micro-Tom plants were inoculated with 16 well-known fungal, bacterial, and viral pathogens of tomato. Athelia rolfsii, Botryotinia fuckeliana, Oidium sp., Phytophthora infestans, and Sclerotinia sclerotiorum caused typical symptoms and sporulated abundantly on Micro-Tom. Micro-Tom was resistant to Alternaria alternata, Corynespora cassiicola, and Fusarium oxysporum. When Micro-Tom was inoculated with 17 isolates of Ralstonia solanacearum, many isolates induced wilt symptoms. Agrobacterium tumefaciens also was pathogenic, causing crown galls on stem tissue after needle prick inoculation. In Micro-Tom sprayed with Pseudomonas syringae pv. tomato, P. s. pv. tabaci, or P. s. pv. glycinea, bacterial populations did not increase, and yellow lesions appeared only on leaves sprayed with P. s. pv. tomato. Tomato mosaic virus, Tomato aspermy virus, and Cucumber mosaic virus systemically infected Micro-Tom, which developed symptoms characteristic of other cultivars of tomato after infection with the respective virus. These results indicated that Micro-Tom was generally susceptible to most of the important tomato pathogens and developed typical symptoms, whereas certain pathogens were restricted by either hypersensitive resistance or nonhost resistance on Micro-Tom. Therefore, an assortment of Micro-Tom-pathogen systems should provide excellent models for studying the mechanism of susceptible and resistant interactions between plants and pathogens. © The Phytopathological Society of Japan and Springer-Verlag 2005.

DOI： 10.1007/s10327-004-0168-x

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DOI： 10.1007/s10327-005-0185-4

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記述言語：英語   掲載種別：研究発表ペーパー・要旨（国際会議）   出版者・発行元：OXFORD UNIV PRESS  

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記述言語：英語   掲載種別：研究発表ペーパー・要旨（国際会議）   出版者・発行元：OXFORD UNIV PRESS  

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記述言語：日本語  

J-GLOBAL

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記述言語：英語  

We transformed Colletotrichum trifolii, the causal agent of alfalfa anthracnose, using Agrobacterium tumefaciens as a new tool for random insertional mutagenesis. Fungal spores of C. trifolii were transformed with T-DNA including the hygromycin phosphotransferase gene (hph). Southern analysis showed that every randomly selected transformant had a unique hybridization pattern of T-DNA, suggesting that the T-DNA was randomly integrated into the fungal genome. More significantly, about 75% of transformants had a single copy of the T-DNA. The results demonstrate that insertional mutagenesis via A. tumefaciens is a useful tool for studying the function of C. trifolii genes.

DOI： 10.1007/s10327-003-0099-y

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記述言語：英語  

We transformed Colletotrichum trifolii, the causal agent of alfalfa anthracnose, using Agrobacterium tumefaciens as a new tool for random insertional mutagenesis. Fungal spores of C. trifolii were transformed with T-DNA including the hygromycin phosphotransferase gene (hph). Southern analysis showed that every randomly selected transformant had a unique hybridization pattern of T-DNA, suggesting that the T-DNA was randomly integrated into the fungal genome. More significantly, about 75% of transformants had a single copy of the T-DNA. The results demonstrate that insertional mutagenesis via A. tumefaciens is a useful tool for studying the function of C. trifolii genes.

DOI： 10.1007/s10327-003-0099-y

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担当区分：最終著者,　責任著者   記述言語：英語   出版者・発行元：SPRINGER-VERLAG  

Recently, we observed that expression of a pea gene (S64) encoding an oxophytodienoic acid reductase (OPR) was induced by a suppressor of pea defense responses, secreted by the pea pathogen Mycosphaerella pinodes. Because it is known that OPRs are usually encoded by families of homologous genes, we screened for genomic and cDNA clones encoding members of this putative OPR family in pea. We isolated five members of the OPR gene family from a pea genomic DNA library, and amplified six cDNA clones, including S64, by RT-PCR (reverse transcriptase-PCR). Sequencing analysis revealed that S64 corresponds to PsOPR2, and the amino acid sequences of the predicted products of the six OPR-like genes shared more than 80% identity with each other. Based on their sequence similarity, all these OPR-like genes code for OPRs of subgroup I, i.e., enzymes which are not required for jasmonic acid biosynthesis. However, the genes varied in their exon/intron organization and in their promoter sequences. To investigate the expression of each individual OPR-like gene, RT-PCR was performed using gene-specific primers. The results indicated that the OPR-like gene most strongly induced by the inoculation of pea plants with a compatible pathogen and by treatment with the suppressor from M. pinodes was PsOPR2. Furthermore, the ability of the six recombinant OPR-like proteins to reduce a model substrate, 2-cyclohexen-1-one (2-CyHE), was investigated. The results indicated that PsOPR1, 4 and 6 display robust activity, and PsOPR2 has a most remarkable ability to reduce 2-CyHE, whereas PsOPR3 has little and PsOPR5 does not reduce this compound. Thus, the six OPR-like proteins can be classified into four types. Interestingly, the gene structures, expression profiles, and enzymatic activities used to classify each member of the pea OPR-like gene family are clearly correlated, indicating that each member of this OPR-like family has a distinct function.

DOI： 10.1007/s00438-003-0948-6

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記述言語：英語   出版者・発行元：ACADEMIC PRESS LTD ELSEVIER SCIENCE LTD  

A polypeptide fungal suppressor from a pea pathogen Mycosphaerella pinodes plays a key role in pathogenesis by suppressing elicitor-induced defense response(s) in pea (Pisum sativum L). In this study, we show that treatment of pea tissues with the polysaccharide elicitor secreted by M. pinodes results in rapid increased activation of two myelin basic protein (MBP)-dependent kinases p44 (approximate to44 kDa) and p48 (approximate to48 kDa) within 15-30 min upon elicitation. Interestingly, the suppressor inhibited the elicitor-induced activation of only p44 kinase. While the defense-inducing signalling molecules, chitosan and salicylic acid (SA) activated the p44 and p48 kinases, methyl jasmonate (MeJA) did not. The abiotic stress signals, abscisic acid (ABA), NaCl and wounding activated the p48 kinase alone. These results demonstrate that MAPKs are differentially activated in response to pathogen invasion and abiotic stress in pea. Furthermore, specific inhibition of elicitor-induced p44 kinase activation by a MAPKK inhibitor, PD098059 and protein kinase inhibitor, K252a correlated with the suppression of elicitor-induced phenylalanine ammonia lyase (PAL) gene expression, supporting a role for p44 in the elicitor-induced defense response(s) in pea. Inhibition of p44 by the phosphoinositide (PI) turnover inhibitor, neomycin (a fungal suppressor mimic), and potentiation of p44 by the diacylglycerol (DAG) kinase inhibitor, R59022 indicated that p44 may be acting downstream of (PI) metabolism. Taken together, our results indicate that suppressor of defense elicitation from M. pinodes acts through inhibition of a MAPK (p44), possibly through a PI signaling pathway, facilitating the establishment of basic compatibility during infection of pea. (C) 2004 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.pmpp.2004.05.003

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記述言語：英語   出版者・発行元：ACADEMIC PRESS LTD ELSEVIER SCIENCE LTD  

A polypeptide fungal suppressor from a pea pathogen Mycosphaerella pinodes plays a key role in pathogenesis by suppressing elicitor-induced defense response(s) in pea (Pisum sativum L). In this study, we show that treatment of pea tissues with the polysaccharide elicitor secreted by M. pinodes results in rapid increased activation of two myelin basic protein (MBP)-dependent kinases p44 (approximate to44 kDa) and p48 (approximate to48 kDa) within 15-30 min upon elicitation. Interestingly, the suppressor inhibited the elicitor-induced activation of only p44 kinase. While the defense-inducing signalling molecules, chitosan and salicylic acid (SA) activated the p44 and p48 kinases, methyl jasmonate (MeJA) did not. The abiotic stress signals, abscisic acid (ABA), NaCl and wounding activated the p48 kinase alone. These results demonstrate that MAPKs are differentially activated in response to pathogen invasion and abiotic stress in pea. Furthermore, specific inhibition of elicitor-induced p44 kinase activation by a MAPKK inhibitor, PD098059 and protein kinase inhibitor, K252a correlated with the suppression of elicitor-induced phenylalanine ammonia lyase (PAL) gene expression, supporting a role for p44 in the elicitor-induced defense response(s) in pea. Inhibition of p44 by the phosphoinositide (PI) turnover inhibitor, neomycin (a fungal suppressor mimic), and potentiation of p44 by the diacylglycerol (DAG) kinase inhibitor, R59022 indicated that p44 may be acting downstream of (PI) metabolism. Taken together, our results indicate that suppressor of defense elicitation from M. pinodes acts through inhibition of a MAPK (p44), possibly through a PI signaling pathway, facilitating the establishment of basic compatibility during infection of pea. (C) 2004 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.pmpp.2004.05.003

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記述言語：英語   掲載種別：研究発表ペーパー・要旨（国際会議）   出版者・発行元：OXFORD UNIV PRESS  

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担当区分：最終著者,　責任著者   記述言語：英語  

DOI： 10.1266/ggs.78.409

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記述言語：英語   出版者・発行元：EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER  

To investigate the factor that determines incompatible interactions between Pseudomonas syringae pv. tabaci and non-host plants, an elicitor of hypersensitive reaction (HR) was partially purified from the supernatant of a nutrient-poor medium of bacterial culture by DEAE column chromatography. The major protein in the elicitor-active fractions was identified as a flagellin which is a component of flagellar filaments. The flagellins purified from P. syringae pv. tomato and glycinea, incompatible pathogens of tobacco plants, induced fragmentation of chromosomal DNA and oxidative burst accompanied by programmed cell death in tobacco (Nicotiana tabacum) Bright Yellow (BY-2) cells, but the flagellin from pv. tabaci, a compatible pathogen, did not. However, the amino acid sequences of flagellins deduced from fliC genes showed a high homology among these P. syringae pathovars. In particular, the amino acid sequences of pv. tabaci and glycinea are completely identical. However, both recombinant flagellins produced in Escherichia coli possess HR-inducing activity in BY-2 cells. These results indicate that the post-translational modification of flagellins has an important role for HR-inducing ability in tobacco cells. Furthermore, we discuss the cause of a different elicitor activity among flagellins on tobacco cells and the role of flagellins in the determining specificity. (C) 2002 Editions scientifiques et medicales Elsevier SAS. All rights reserved.

DOI： 10.1016/S0981-9428(02)00018-9

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DOI： 10.1007/s10327-003-0045-z

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DOI： 10.1007/s10327-003-0045-z

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記述言語：英語  

The Dof protein family is a group of plant transcription factors carrying highly conserved 52 residues referred to as the Dof domain, and belongs to the C4 zinc-finger transcription factors. We isolated various PsDof genes by PCR using the Dof-domain nucleotide sequence of the PsDofl gene from a cDNA library of elicitor-treated pea epicotyls, and these isolated PsDof genes were then classified phylogenetically. Since the obtained genes (PsDofl to PsDofT) were scattered over various positions of the phylogenetic tree, they were expected to perform various functions as Dof-type transcription factors. From their positions in the tree, it is expected that the PsDofZ and PsDof5 genes are defense related, as is the PsDofl gene. © 2003, Japanese Society for Plant Cell and Molecular Biology. All rights reserved.

DOI： 10.5511/plantbiotechnology.20.247

Scopus

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記述言語：英語  

The Dof protein family is a group of plant transcription factors carrying highly conserved 52 residues referred to as the Dof domain, and belongs to the C4 zinc-finger transcription factors. We isolated various PsDof genes by PCR using the Dof-domain nucleotide sequence of the PsDofl gene from a cDNA library of elicitor-treated pea epicotyls, and these isolated PsDof genes were then classified phylogenetically. Since the obtained genes (PsDofl to PsDofT) were scattered over various positions of the phylogenetic tree, they were expected to perform various functions as Dof-type transcription factors. From their positions in the tree, it is expected that the PsDofZ and PsDof5 genes are defense related, as is the PsDofl gene. © 2003, Japanese Society for Plant Cell and Molecular Biology. All rights reserved.

DOI： 10.5511/plantbiotechnology.20.247

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DOI： 10.1007/s10327-003-0061-z

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DOI： 10.1007/s10327-003-0061-z

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担当区分：筆頭著者,　責任著者   記述言語：英語  

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DOI： 10.1093/pcp/pcg042

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記述言語：日本語   出版者・発行元：Japan Society for Bioscience, Biotechnology, and Agrochemistry  

DOI： 10.1271/kagakutoseibutsu1962.41.511

CiNii Article

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記述言語：英語   出版者・発行元：岡山大学農学部  

Recently, we, isolated cDNA clone, PsDof1, from clicitor-treated pea cDNA library. The putative gene product, a PsDof1, encodes DNA binding protein that specifically binds the DNA fragment containing AAAG core sequence. In this paper we report that GST-PsDof1 fusion protein specifically binds to the promoter region containing AAAG core sequence(s) of PsCHS1, one of the elicitor-inducible genes encoding chalcone synthase (CHS). Furthermore the addition of DNA fragment containing AAAG motif to the 35S minimal promoter provided the elicitor-responsibility in transient transfection assay using pea protoplasts. These results suggest that PsDof1 might be involved in defense responses by acitivating the transcription by a binding to AAAG core sequence in the promoter of the defense-related genes in pea.エリシターを処理したエンドウ上胚軸由来のRNAから作成されたcDNAライブラリーからエリシター処理により発現が増高する遺伝子候補のcDNAとしてPsDof1が単離された．大腸菌で生産されたGST-PsDof１融合タンパク質はAAAG配列をコアとするDNAに結合することが明らかにされている．本論文ではGST-PsDof１がエリシター応答性遺伝子の一つ，PsCHS1のプロモーター上のAAAGまたはCTTT配列を有する断片に特異的に結合することを明らかにした．更にAAAG配列のエリシター応答性シスエレメントとしての機能を解析するため，AAAG配列を４回繰り返したユニットをCaMV35Ｓの最小プロモーターとCATレポーター遺伝子に連結したキメラ遺伝子を構築し，エンドウプロトプラストにエレクトロポレーション法により導入した．CAT活性を指にプロモーター活性を調べたところ，AAAG配列を有するプロモーターは，エリシター処理により活性化されることが明らかとなった．これらの結果はPsDof１がエリシター応答性防御遺伝子のプロモーター上のAAAG配列に結合し，転写を活性化させる可能性を示唆している．

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DOI： 10.1007/s10327-002-0003-1

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DOI： 10.1007/s10327-002-0003-1

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記述言語：日本語   出版者・発行元：日本植物病理学会  

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記述言語：日本語   出版者・発行元：日本植物病理学会  

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記述言語：日本語   出版者・発行元：日本植物病理学会  

CiNii Article

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記述言語：日本語  

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