Faculty Profiles - ICHINOSE Yuki

MISC - ICHINOSE Yuki

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The Siderophore Pyoverdine of Pseudomonas syringae pv. tabaci 6605 Is an Intrinsic Virulence Factor in Host Tobacco Infection Reviewed

Fumiko Taguchi, Tomoko Suzuki, Yoshishige Inagaki, Kazuhiro Toyoda, Tomonori Shiraishi, Yuki Ichinose

Journal of Bacteriology 192 ( 1 ) 117 - 126 2010.1

Authorship：Last author,　Corresponding author Language：English Publisher：American Society for Microbiology

<title>ABSTRACT</title>

To investigate the role of iron uptake mediated by the siderophore pyoverdine in the virulence of the plant pathogen
<italic>Pseudomonas syringae</italic>
pv. tabaci 6605, three predicted pyoverdine synthesis-related genes,
<italic>pvdJ</italic>
,
<italic>pvdL</italic>
, and
<italic>fpvA</italic>
, were mutated. The
<italic>pvdJ</italic>
,
<italic>pvdL</italic>
, and
<italic>fpvA</italic>
genes encode the pyoverdine side chain peptide synthetase III
<sc>l</sc>
-Thr-
<sc>l</sc>
-Ser component, the pyoverdine chromophore synthetase, and the TonB-dependent ferripyoverdine receptor, respectively. The Δ
<italic>pvdJ</italic>
and Δ
<italic>pvdL</italic>
mutants were unable to produce pyoverdine in mineral salts-glucose medium, which was used for the iron-depleted condition. Furthermore, the Δ
<italic>pvdJ</italic>
and Δ
<italic>pvdL</italic>
mutants showed lower abilities to produce tabtoxin, extracellular polysaccharide, and acyl homoserine lactones (AHLs), which are quorum-sensing molecules, and consequently had reduced virulence on host tobacco plants. In contrast, all of the mutants had accelerated swarming ability and increased biosurfactant production, suggesting that swarming motility and biosurfactant production might be negatively controlled by pyoverdine. Scanning electron micrographs of the surfaces of tobacco leaves inoculated with the mutant strains revealed only small amounts of extracellular polymeric matrix around these mutants, indicating disruption of the mature biofilm. Tolerance to antibiotics was drastically increased for the Δ
<italic>pvdL</italic>
mutant, as for the Δ
<italic>psyI</italic>
mutant, which is defective in AHL production. These results demonstrated that pyoverdine synthesis and the quorum-sensing system of
<italic>Pseudomonas syringae</italic>
pv. tabaci 6605 are indispensable for virulence in host tobacco infection and that AHL may negatively regulate tolerance to antibiotics.

DOI： 10.1128/jb.00689-09

Bacterial DNA activates immunity in Arabidopsis thaliana

Suguru Yakushiji, Yasuhiro Ishiga, Yoshishige Inagaki, Kazuhiro Toyoda, Tomonori Shiraishi, Yuki Ichinose

JOURNAL OF GENERAL PLANT PATHOLOGY 75 ( 3 ) 227 - 234 2009.6

Language：English Publisher：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

Bacterial DNA activates immunity in Arabidopsis thaliana

Suguru Yakushiji, Yasuhiro Ishiga, Yoshishige Inagaki, Kazuhiro Toyoda, Tomonori Shiraishi, Yuki Ichinose

Journal of General Plant Pathology 75 ( 3 ) 227 - 234 2009.6

Authorship：Last author,　Corresponding author Language：English Publisher：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

Other Link： http://link.springer.com/article/10.1007/s10327-009-0162-4/fulltext.html

Enhanced Defense Responses in Arabidopsis Induced by the Cell Wall Protein Fractions from Pythium oligandrum Require SGT1, RAR1, NPR1 and JAR1

Yoko Kawamura, Shigehito Takenaka, Shu Hase, Mayumi Kubota, Yuki Ichinose, Yoshinori Kanayama, Kazuhiro Nakaho, Daniel F. Klessig, Hideki Takahashi

Plant and Cell Physiology 50 ( 5 ) 924 - 934 2009.5

Language：English Publisher：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

Enhanced Defense Responses in Arabidopsis Induced by the Cell Wall Protein Fractions from Pythium oligandrum Require SGT1, RAR1, NPR1 and JAR1

Yoko Kawamura, Shigehito Takenaka, Shu Hase, Mayumi Kubota, Yuki Ichinose, Yoshinori Kanayama, Kazuhiro Nakaho, Daniel F. Klessig, Hideki Takahashi

PLANT AND CELL PHYSIOLOGY 50 ( 5 ) 924 - 934 2009.5

Language：English Publisher：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

High Level Expression of a Virus Resistance Gene, RCY1, Confers Extreme Resistance to Cucumber mosaic virus in Arabidopsis thaliana

Ken-Taro Sekine, Sayaka Kawakami, Shu Hase, Mayumi Kubota, Yuki Ichinose, Jyoti Shah, Hong-Gu Kang, Daniel F. Klessig, Hideki Takahashi

MOLECULAR PLANT-MICROBE INTERACTIONS 21 ( 11 ) 1398 - 1407 2008.11

Language：English Publisher：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

High Level Expression of a Virus Resistance Gene, RCY1, Confers Extreme Resistance to Cucumber mosaic virus in Arabidopsis thaliana

Ken-Taro Sekine, Sayaka Kawakami, Shu Hase, Mayumi Kubota, Yuki Ichinose, Jyoti Shah, Hong-Gu Kang, Daniel F. Klessig, Hideki Takahashi

MOLECULAR PLANT-MICROBE INTERACTIONS 21 ( 11 ) 1398 - 1407 2008.11

Language：English Publisher：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

Biological Control of Crown Gall of Grapevine, Rose, and Tomato by Nonpathogenic Agrobacterium vitis Strain VAR03-1

A. Kawaguchi, K. Inoue, Y. Ichinose

PHYTOPATHOLOGY 98 ( 11 ) 1218 - 1225 2008.11

Authorship：Last author Language：English Publisher：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

Biological Control of Crown Gall of Grapevine, Rose, and Tomato by Nonpathogenic Agrobacterium vitis Strain VAR03-1

A. Kawaguchi, K. Inoue, Y. Ichinose

PHYTOPATHOLOGY 98 ( 11 ) 1218 - 1225 2008.11

Language：English Publisher：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

Amino Acid Sequence of Bacterial Microbe-Associated Molecular Pattern flg22 Is Required for Virulence International journal

Kana Naito, Fumiko Taguchi, Tomoko Suzuki, Yoshishige Inagaki, Kazuhiro Toyoda, Tomonori Shiraishi, Yuki Ichinose

MOLECULAR PLANT-MICROBE INTERACTIONS 21 ( 9 ) 1165 - 1174 2008.9

Authorship：Last author,　Corresponding author Language：English Publisher：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

Amino Acid Sequence of Bacterial Microbe-Associated Molecular Pattern flg22 Is Required for Virulence

Kana Naito, Fumiko Taguchi, Tomoko Suzuki, Yoshishige Inagaki, Kazuhiro Toyoda, Tomonori Shiraishi, Yuki Ichinose

MOLECULAR PLANT-MICROBE INTERACTIONS 21 ( 9 ) 1165 - 1174 2008.9

Language：English Publisher：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

(129) Molecular Analysis for Oxidosqualene Cyclase in Saponin Biosynthesis Pathway of Rice(Abstracts of the Papers Presented at the Annual Meeting of the Society)

Inagaki Y., Imaoka A., Fujita K., Arase S., Toyoda K., Shiraishi T., Ichinose Y., Osbourn Anne

Annals of the Phytopathological Society of Japan 74 ( 3 ) 201 - 201 2008.8

(308) Structural Analysis of Flagellin Glycan and Functional Analysis of Genes Involved in Flagellin Glycosylation in Pseudomonas syringae(Abstracts of the Papers Presented at the Annual Meeting of the Society)

Tsunemi K, Taguchi F, Takeuchi K, Ishii T, Yoshida M, Ono Y, Kameyama M, Ichinose Y

Annals of the Phytopathological Society of Japan 74 ( 3 ) 249 - 249 2008.8

(127) Functional Analysis of Cell Wall-associated apyrase MtAPY1; 1 in Medicago truncatula(Abstracts of the Papers Presented at the Annual Meeting of the Society)

Shiobara T., Fujita K., Inagaki Y., Ichinose Y., Toyoda K., Shiraishi T.

Annals of the Phytopathological Society of Japan 74 ( 3 ) 200 - 200 2008.8

Phylogenetic and serological analyses reveal genetic diversity of Agrobacterium vitis strains in Japan

A. Kawaguchi, H. Sawada, Y. Ichinose

PLANT PATHOLOGY 57 ( 4 ) 747 - 753 2008.8

Authorship：Last author Language：English Publisher：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

Phylogenetic and serological analyses reveal genetic diversity of Agrobacterium vitis strains in Japan

A. Kawaguchi, H. Sawada, Y. Ichinose

PLANT PATHOLOGY 57 ( 4 ) 747 - 753 2008.8

Language：English Publisher：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

Polyphosphate kinase is essential for swarming motility, tolerance to environmental stresses, and virulence in Pseudomonas syringae pv. tabaci 6605

Md. Mijan Hossain, Chiharu Tani, Tomoko Suzuki, Fumiko Taguchi, Tatsuhiro Ezawa, Yuki Ichinose

PHYSIOLOGICAL AND MOLECULAR PLANT PATHOLOGY 72 ( 4-6 ) 122 - 127 2008.7

Authorship：Last author,　Corresponding author Language：English Publisher：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

Polyphosphate kinase is essential for swarming motility, tolerance to environmental stresses, and virulence in Pseudomonas syringae pv. tabaci 6605

Md. Mijan Hossain, Chiharu Tani, Tomoko Suzuki, Fumiko Taguchi, Tatsuhiro Ezawa, Yuki Ichinose

PHYSIOLOGICAL AND MOLECULAR PLANT PATHOLOGY 72 ( 4-6 ) 122 - 127 2008.7

Language：English Publisher：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

Gac two-component system in Pseudomonas syringae pv. tabaci is required for virulence but not for hypersensitive reaction

Mizuri Marutani, Fumiko Taguchi, Yujiro Ogawa, Md. Mijan Hossain, Yoshishige Inagaki, Kazuhiro Toyoda, Tomonori Shiraishi, Yuki Ichinose

MOLECULAR GENETICS AND GENOMICS 279 ( 4 ) 313 - 322 2008.4

Language：English Publisher：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

Gac two-component system in Pseudomonas syringae pv. tabaci is required for virulence but not for hypersensitive reaction

Mizuri Marutani, Fumiko Taguchi, Yujiro Ogawa, Md. Mijan Hossain, Yoshishige Inagaki, Kazuhiro Toyoda, Tomonori Shiraishi, Yuki Ichinose

MOLECULAR GENETICS AND GENOMICS 279 ( 4 ) 313 - 322 2008.4

Authorship：Last author,　Corresponding author Language：English Publisher：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

Other Link： http://link.springer.com/article/10.1007/s00438-007-0309-y/fulltext.html

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