出版者・発行元：Cold Spring Harbor Laboratory  

Seasonal changes in spring induce flowering by expressing the florigen, FLOWERING LOCUS T (FT), in Arabidopsis. FT is expressed in unique phloem companion cells with unknown characteristics. The question of which genes are co-expressed with FT and whether they have roles in flowering remains elusive. Through tissue-specific translatome analysis, we discovered that under long-day conditions with the natural sunlight red/far-red ratio, the FT-producing cells express a gene encoding FPF1-LIKE PROTEIN 1 (FLP1). The master FT regulator, CONSTANS (CO), controls FLP1 expression, suggesting FLP1's involvement in the photoperiod pathway. FLP1 promotes early flowering independently of FT, is active in the shoot apical meristem, and induces the expression of SEPALLATA 3 (SEP3), a key E-class homeotic gene. Unlike FT, FLP1 facilitates inflorescence stem elongation. Our cumulative evidence indicates that FLP1 may act as a mobile signal. Thus, FLP1 orchestrates floral initiation together with FT and promotes inflorescence stem elongation during reproductive transitions.

DOI： 10.1101/2024.04.26.591289

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掲載種別：研究論文（学術雑誌）  

In the inducible chlorosis model tobacco, i-hpHSP90C, the silencing of HSP90C activated both salicylic acid (SA)- and cell death-related gene expression and sporadic cell death, resulting in severe chlorosis. In this model plant, we found a transient SA accumulation to a significantly high level at 8 h after induction of HSP90C silencing and consistent upregulation of CBP60-type transcription factors and some SA biosynthetic genes. Exogenous treatment of the model plant with SA alone did not induce chlorosis. The introgression of a gene encoding SA-degrading enzyme, nahGA430V, into tobacco plants with functional N′ tobamovirus resistance gene partially compromised their resistance to tomato mosaic virus but without a clear reduction in SA levels. Expression of nahGA430V stochastically alleviated chlorosis and, subsequently, sporadic cell death upon induction of HSP90C silencing. We applied tenoxicam, a potent inhibitor of the NPR1-dependent SA signaling pathway in Arabidopsis, and found that it alleviated chlorosis in i-hpHSP90C, which accompanied a reduced expression of a CBP60-type transcription factor. However, the expression of PR1a, a well-characterized SA signal marker, was not suppressed by tenoxicam in the i-hpHSP90 plants with alleviated chlorosis. The findings collectively suggest that the plant immunity-related response, including SA production, could have a role in increasing the severity of chlorosis, although the underlying mechanisms remain to be elucidated.

DOI： 10.1007/s10327-024-01191-3

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掲載種別：研究論文（学術雑誌）   出版者・発行元：Elsevier BV  

DOI： 10.1016/j.plantsci.2023.111840

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Dihydroxyacetone (DHA) occurs in wide-ranging organisms including plants and can undergo spontaneous conversion to methylglyoxal (MG). While the toxicity of MG to plants is well-known, the toxicity of DHA to plants remains to be elucidated. We investigated the effects of DHA and MG on Arabidopsis. Exogenous DHA at up to 10 m m did not affect the radicle emergence, the expansion of green cotyledons, the seedling growth, or the activity of glyoxalase II while DHA at 10 m m inhibited the root elongation and increased the activity of glyoxalase I. Exogenous MG at 1.0 m m inhibited these physiological responses and increased both activities. DHA at 10 m m increased the MG content in the roots. These results indicate that DHA is not so toxic as MG in Arabidopsis seeds and seedlings and suggest that the toxic effect of DHA at high concentrations is attributed to MG accumulation by the conversion to MG.

DOI： 10.1093/bbb/zbad109

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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  

The depletion of cellular zinc (Zn) adversely affects plant growth. Plants have adaptation mechanisms for Zn-deficient conditions, inhibiting growth through the action of transcription factors and metal transporters. We previously identified three defensin-like (DEFL) proteins (DEFL203, DEFL206 and DEFL208) that were induced in Arabidopsis thaliana roots under Zn-depleted conditions. DEFLs are small cysteine-rich peptides involved in defense responses, development and excess metal stress in plants. However, the functions of DEFLs in the Zn-deficiency response are largely unknown. Here, phylogenetic tree analysis revealed that seven DEFLs (DEFL202-DEFL208) were categorized into one subgroup. Among the seven DEFLs, the transcripts of five (not DEFL204 and DEFL205) were upregulated by Zn deficiency, consistent with the presence of cis-elements for basic-region leucine-zipper 19 (bZIP19) or bZIP23 in their promoter regions. Microscopic observation of GFP-tagged DEFL203 showed that DEFL203-sGFP was localized to the apoplast and plasma membrane. Whereas a single mutation of the DEFL202 or DEFL203 genes only slightly affected root growth, defl202 defl203 double mutants showed enhanced root growth under all growth conditions. We also showed that the size of the root meristem was increased in the double mutants compared with the wild type. Our results suggest that DEFL202 and DEFL203 are redundantly involved in the inhibition of root growth under Zn-deficient conditions through a reduction in root meristem length and cell number.

DOI： 10.1111/tpj.16281

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担当区分：筆頭著者,　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：American Chemical Society (ACS)  

DOI： 10.1021/acs.jafc.2c08479

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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  

<title>Abstract</title>Perception of pathogen-derived ligands by corresponding host receptors is a pivotal strategy in eukaryotic innate immunity. In plants, this is complemented by circadian anticipation of infection timing, promoting basal resistance even in the absence of pathogen threat. Here, we report that trichomes, hair-like structures on the epidermis, directly sense external mechanical forces, including raindrops, to anticipate pathogen infections in <italic>Arabidopsis thaliana</italic>. Exposure of leaf surfaces to mechanical stimuli initiates the concentric propagation of intercellular calcium waves away from trichomes to induce defence-related genes. Propagating calcium waves enable effective immunity against pathogenic microbes through the CALMODULIN-BINDING TRANSCRIPTION ACTIVATOR 3 (CAMTA3) and mitogen-activated protein kinases. We propose an early layer of plant immunity in which trichomes function as mechanosensory cells that detect potential risks.

DOI： 10.1038/s41467-022-28813-8

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その他リンク： https://www.nature.com/articles/s41467-022-28813-8

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)  

The ubiquitin-proteasome system is vital to hormone-mediated developmental and stress responses in plants. Ubiquitin ligases target hormone-specific transcriptional activators (TAs) for degradation, but how TAs are processed by proteasomes remains unknown. We report that in Arabidopsis , the salicylic acid– and ethylene-responsive TAs, NPR1 and EIN3, are relayed from pathway-specific ubiquitin ligases to proteasome-associated HECT-type UPL3/4 ligases. Activity and stability of NPR1 were regulated by sequential action of three ubiquitin ligases, including UPL3/4, while proteasome processing of EIN3 required physical handover between ethylene-responsive SCF ^EBF2 and UPL3/4 ligases. Consequently, UPL3/4 controlled extensive hormone-induced developmental and stress-responsive transcriptional programs. Thus, our findings identify unknown ubiquitin ligase relays that terminate with proteasome-associated HECT-type ligases, which may be a universal mechanism for processive degradation of proteasome-targeted TAs and other substrates.

DOI： 10.1126/sciadv.abn4466

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掲載種別：研究論文（学術雑誌）   出版者・発行元：Wiley  

DOI： 10.1111/pce.14373

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その他リンク： https://onlinelibrary.wiley.com/doi/full-xml/10.1111/pce.14373

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  

SUMMARY

Increasing the vegetative growth period of crops can increase biomass and grain yield. In rice (Oryza sativa), the concentration of trans ‐zeatin, an active cytokinin, was high in the leaves during vegetative growth and decreased rapidly upon induction of florigen expression, suggesting that this hormone is involved in the regulation of the vegetative phase. To elucidate whether exogenous cytokinin application influences the length of the vegetative phase, we applied 6‐benzylaminopurine (BAP) to rice plants at various developmental stages. Our treatment delayed flowering time by 8–9 days when compared with mock‐treated rice plants, but only at the transition stage when the flowering signals were produced. Our observations also showed that flowering in the paddy field is delayed by thidiazuron, a stable chemical that mimics the effects of cytokinin. The transcript levels of florigen genes Heading date 3a (Hd3a) and Rice Flowering locus T1 (RFT1) were significantly reduced by the treatment, but the expression of Early heading date 1 (Ehd1), a gene found directly upstream of the florigen genes, was not altered. In maize (Zea mays), similarly, BAP treatment increased the vegetative phage by inhibiting the expression of ZCN8, an ortholog of Hd3a. We showed that cytokinin treatment induced the expression of two type‐A response regulators (OsRR1 and OsRR2) which interacted with Ehd1, a type‐B response regulator. We also observed that cytokinin did not affect flowering time in ehd1 knockout mutants. Our study indicates that cytokinin application increases the duration of the vegetative phase by delaying the expression of florigen genes in rice and maize by inhibiting Ehd1.

DOI： 10.1111/tpj.15760

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その他リンク： https://onlinelibrary.wiley.com/doi/full-xml/10.1111/tpj.15760

記述言語：英語   掲載種別：研究論文（学術雑誌）  

To acclimate to waterlogged conditions, wetland plants form a barrier to radial oxygen loss (ROL) that can enhance oxygen transport to the root apex. We hypothesized that one or more hormones are involved in the induction of the barrier and searched for such hormones in rice. We previously identified 98 genes that were tissue-specifically upregulated during ROL barrier formation in rice. The RiceXPro database showed that most of these genes were highly enhanced by exogenous abscisic acid (ABA). We then examined the effect of ABA on ROL barrier formation by using an ABA biosynthesis inhibitor (fluridone, FLU), by applying exogenous ABA and by examining a mutant with a defective ABA biosynthesis gene (osaba1). FLU suppressed barrier formation in a stagnant solution that mimics waterlogged soil. Under aerobic conditions, rice does not naturally form a barrier, but 24 h of ABA treatment induced barrier formation. osaba1 did not form a barrier under stagnant conditions, but the application of ABA rescued the barrier. In parallel with ROL barrier formation, suberin lamellae formed in the exodermis. These findings strongly suggest that ABA is an inducer of suberin lamellae formation in the exodermis, resulting in an ROL barrier formation in rice.

DOI： 10.1111/nph.17751

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担当区分：筆頭著者,　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 Science and Business Media {LLC}  

It is known that rice roots take up cadmium (Cd) via the symplastic route mediated by membrane-bound mineral transporters. Here we provide evidence that apoplastic bypass flow is another Cd uptake route in rice. High concentrations of Cd rendered apoplastic bypass flow rate increased in rice seedlings. These concentrations of Cd compromised membrane integrity in the root meristem and transition zone. Polyethleneglycol and proline inhibited the Cd-induced apoplastic bypass flow and Cd transfer to the shoots. Loss-of-function mutant of the Cd uptake transporter, nramp5, showed Cd transport to the shoot comparable to the wild type. At a low Cd concentration, increased apoplastic bypass flow rate by NaCl stress resulted in an elevation of Cd transport to shoots both in the wildtype and nramp5. These observations indicate that apoplastic bypass flow in roots carries Cd transport leading to xylem loading of Cd in addition to the symplastic pathway mediated by mineral transporters under stressed conditions.

DOI： 10.1007/s10265-021-01319-y

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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：Oxford University Press ({OUP})  

Plastids are involved in phytohormone metabolism as well as photosynthesis. However, the mechanism by which plastid retrograde signals and phytohormones cooperatively regulate plastid biogenesis remains elusive. Here, we investigated the effects of an inhibitor and a mutation that generate biogenic plastid signals on phytohormones, and vice versa. Inhibition of plastid biogenesis by norflurazon (NF)-treatment and the plastid protein import2 (ppi2) mutation caused a decrease in salicylic acid (SA) and jasmonic acid (JA). This effect can be attributed in part to the altered expression of genes involved in the biosynthesis and metabolism of SA and JA. However, SA-dependent induction of the PATHOGENESIS-RELATED1 gene was virtually unaffected in NF-treated plants and the ppi2 mutant. Instead, the level of chlorophyll in these plants was partially restored by exogenous application of SA. Consistent with this observation, the levels of some photosynthesis-associated proteins increased in the ppi2 and NF-treated plants in response to SA treatment. This regulation in true leaves seems to occur at post-transcriptional level, since SA treatment did not induce the expression of photosynthesis associated genes. In salicylic acid induction deficient 2 and lesions simulating disease resistance 1 mutants, endogenous SA regulates the accumulation of photosynthesis-associated proteins through transcriptional and post-transcriptional mechanisms. These data indicate that SA acts antagonistically to the inhibition of plastid biogenesis by promoting the accumulation of photosynthesis-associated proteins in Arabidopsis, suggesting a possible link between SA and biogenic plastid signaling.

DOI： 10.1093/pcp/pcab128

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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 GMBH  

The halophyte ice plant (Mesembryanthemum crystallinum) converts its mode of photosynthesis from C3 to crassulacean acid metabolism (CAM) during severe water stress. During the transition to CAM, the plant induces CAM-related genes and changes its diurnal stomatal behavior to take up CO2 efficiently at night. However, limited information concerning this signaling exists. Here, we investigated the changes in the diurnal stomatal behavior of M. crystallinum during its shift in photosynthesis using a detached epidermis. M. crystallinum plants grown under C3 conditions opened their stomata during the day and closed them at night. However, CAMinduced plants closed their stomata during the day and opened them at night. Quantitative analysis of endogenous phytohormones revealed that trans-zeatin levels were high in CAM-induced plants. In contrast, the levels of jasmonic acid (JA) and JA-isoleucine were severely reduced in CAM-induced plants, specifically at night. CAM induction did not alter the levels of abscisic acid; however, inhibitors of abscisic acid synthesis suppressed CAMinduced stomatal closure. These results indicate that M. crystallinum regulates the diurnal balance of cytokinin and JA during CAM transition to alter stomatal behavior.

DOI： 10.1016/j.jplph.2021.153448

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Rhizoctonia solani is a soil-borne necrotrophic fungus that causes sheath blight in grasses. The basal resistance of compatible interactions between R. solani and rice is known to be modulated by some WRKY transcription factors (TFs). However, genes and defense responses involved in incompatible interaction with R. solani remain unexplored, because no such interactions are known in any host plants. Recently, we demonstrated that Bd3-1, an accession of the model grass Brachypodium distachyon, is resistant to R. solani and, upon inoculation with the fungus, undergoes rapid induction of genes responsive to the phytohormone salicylic acid (SA) that encode the WRKY TFs BdWRKY38 and BdWRKY44. Here, we show that endogenous SA and these WRKY TFs positively regulate this accession-specific R. solani resistance. In contrast to a susceptible accession (Bd21), the infection process in the resistant accessions Bd3-1 and Tek-3 was suppressed at early stages before the development of fungal biomass and infection machinery. A comparative transcriptome analysis during pathogen infection revealed that putative WRKY-dependent defense genes were induced faster in the resistant accessions than in Bd21. A gene regulatory network (GRN) analysis based on the transcriptome dataset demonstrated that BdWRKY38 was a GRN hub connected to many target genes specifically in resistant accessions, whereas BdWRKY44 was shared in the GRNs of all three accessions. Moreover, overexpression of BdWRKY38 increased R. solani resistance in Bd21. Our findings demonstrate that these resistant accessions can activate an incompatible host response to R. solani, and BdWRKY38 regulates this response by mediating SA signaling.

DOI： 10.1111/tpj.14976

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Plant phenotypes caused by mineral deficiencies differ depending on growth conditions. We recently reported that the growth of Arabidopsis thaliana was severely inhibited on MGRL-based zinc (Zn)-deficient medium but not on Murashige-Skoog-based Zn-deficient medium. Here, we explored the underlying reason for the phenotypic differences in Arabidopsis grown on the different media. The root growth and chlorophyll contents reduced by Zn deficiency were rescued by the addition of extra manganese (Mn) during short-term growth (10 or 14 d). However, this treatment did not affect the growth recovery after long-term growth (38 d). To investigate the reason for plant recovery from Zn deficiency, we performed the RNA-seq analysis of the roots grown on the Zn-basal medium and the Zn-depleted medium with/without additional Mn. Principal component analysis of the RNA-seq data showed that the gene expression patterns of plants on the Zn-basal medium were similar to those on the Zn-depleted medium with Mn, whereas those on the Zn-depleted medium without Mn were different from the others. The expression of several transcription factors and reactive oxygen species (ROS)-related genes was upregulated in only plants on the Zn-depleted medium without Mn. Consistent with the gene expression data, ROS accumulation in the roots grown on this medium was higher than those grown in other conditions. These results suggest that plants accumulate ROS and reduce their biomass under undesirable growth conditions, such as Zn depletion. Taken together, this study shows that the addition of extra Mn to the Zn-depleted medium induces transcriptional changes in ROS-related genes, thereby alleviating short-term growth inhibition due to Zn deficiency.

DOI： 10.1093/pcp/pcaa094

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Peel degreening is an important aspect of fruit ripening in many citrus fruit, and previous studies have shown that it can be advanced by ethylene treatment or by low-temperature storage. However, the important regulators and pathways involved in natural peel degreening remain largely unknown. To determine how natural peel degreening is regulated in lemon fruit (Citrus limon), we studied transcriptome and physiochemical changes in the flavedo in response to ethylene treatment and low temperatures. Treatment with ethylene induced rapid peel degreening, which was strongly inhibited by the ethylene antagonist, 1-methylcyclopropene (1-MCP). Compared with 25 ºC, moderately low storage temperatures of 5-20 °C also triggered peel degreening. Surprisingly, repeated 1-MCP treatments failed to inhibit the peel degreening induced by low temperature. Transcriptome analysis revealed that low temperature and ethylene independently regulated genes associated with chlorophyll degradation, carotenoid metabolism, photosystem proteins, phytohormone biosynthesis and signalling, and transcription factors. Peel degreening of fruit on trees occurred in association with drops in ambient temperature, and it coincided with the differential expression of low temperature-regulated genes. In contrast, genes that were uniquely regulated by ethylene showed no significant expression changes during on-tree peel degreening. Based on these findings, we hypothesize that low temperature plays a prominent role in regulating natural peel degreening independently of ethylene in citrus fruit.

DOI： 10.1093/jxb/eraa206

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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）   出版者・発行元：Informa {UK} Limited  

Reactive oxygen species and nitric oxide (NO•) concomitantly play essential roles in guard cell signaling. Studies using catalase mutants have revealed that the inducible and constitutive elevations of intracellular hydrogen peroxide (H2O2) have different roles: only the inducible H2O2 production transduces the abscisic acid (ABA) signal leading stomatal closure. However, the involvement of inducible or constitutive NO• productions, if exists, in this process remains unknown. We studied H2O2 and NO• mobilization in guard cells of catalase mutants. Constitutive H2O2 level was higher in the mutants than that in wild type, but constitutive NO• level was not different among lines. Induced NO• and H2O2 levels elicited by ABA showed a high correlation with each other in all lines. Furthermore, NO• levels increased by exogenous H2O2 also showed a high correlation with stomatal aperture size. Our results demonstrate that ABA-induced intracellular H2O2 accumulation triggers NO• production leading stomatal closure. ABBREVIATIONS: ABA: abscisic acid; CAT: catalase; cGMP: cyclic guanosine monophosphate; DAF-2DA: 4,5-diaminofluorescein-2 diacetate; H2DCF-DA: 2',7'-dichlorodihydrofluorescein diacetate; MeJA: methyljasmonate; NOS: nitric oxide synthetase; NR: nitrate reductase; POX: peroxidase; ROS: reactive oxygen species; SNAP: S-nitroso-N-acetyl-DL-penicillamine; SNP: sodium nitroprusside; NOX: NADP(H) oxidase.

DOI： 10.1080/09168451.2020.1743168

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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 {BV}  

Toxicity Identification Evaluation (TIE) is a useful method for the classification and identification of toxicants in a composite environment water sample. However, its extension to a larger sample size has been restrained owing to the limited throughput of toxicity bioassays. Here we reported the development of a high-throughput method of TIE Phase I. This newly developed method was assisted by the fluorescence-based cellular oxidation (CO) biosensor fabricated with roGFP2-expressing bacterial cells in 96-well microplate format. The assessment of four river water samples from Langat river basin by this new method demonstrated that the contaminant composition of the four samples can be classified into two distinct groups. The entire toxicity assay consisted of 2338 tests was completed within 12 h with a fluorescence microplate reader. Concurrently, the sample volume for each assay was reduced to 50 μL, which is 600 to 4700 times lesser to compare with conventional bioassays. These imply that the throughput of the CO biosensor-assisted TIE Phase I is now feasible for constructing a large-scale toxicity monitoring system, which would cover a whole watershed scale.

DOI： 10.1016/j.chemosphere.2020.125933

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Black pepper (Piper nigrum L.) is one of the most popular and oldest spices in the world with culinary uses and various pharmacological properties. In order to satisfy the growing worldwide demand for black pepper, improved productivity of pepper is highly desirable. A primary constraint in black pepper production is the non-synchronous nature of flower development and non-uniform fruit ripening within a spike. The uneven ripening of pepper berries results in a high labour requirement for selective harvesting contributes to low productivity and affects the quality of the pepper products. In Malaysia, there are a few recommended varieties for black pepper planting, each having some limitations in addition to the useful characteristics. Therefore, a comparative study of different black pepper varieties will provide a better understanding of the mechanisms regulates fruit development and ripening. Plant hormones are known to influence the fruit development process and their roles in black pepper flower and fruit development were inferred based on the probe-based gene expression analysis and the quantification of the multiple plant hormones using high-performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS). In this study, jasmonic acid and salicylic acid were found to play roles in flowering and fruit setting, whereas auxin, gibberellin and cytokinins are important for fruit growth. Abscisic acid has positive role in fruit maturation and ripening in the development process. Distinct pattern of plant hormones related gene expression profiles with the hormones accumulation profiles suggested a complex network of regulation is involved in the signaling process and crosstalk between plant hormones was another layer of regulation in the black pepper fruit development mechanisms. The current study provides clues to help in elucidating the timing of the action of each specific plant hormone during fruit development and ripening which could be applied to enhance our ability to control the ripening process, leading to improving procedures for the production and post-harvest handling of pepper fruits.

DOI： 10.1007/s10265-019-01156-0

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

This study examined contents of nine plant hormones in developing seeds of field-grown wheat varieties (Triticum aestivum L.) with different seed dormancy using liquid chromatography-mass spectrometry. The varieties showed marked diversity in germination indices at 15°C and 20°C. Contents of the respective hormones in seeds showed a characteristic pattern during seed maturation from 30-day post anthesis to 60-day post anthesis. Principal component analysis and hierarchical clustering analysis revealed that plant hormone profiles were not correlated with dormancy levels, indicating that hormone contents were not associated with preharvest sprouting (PHS) susceptibility. Indole acetic acid (IAA) contents of mature seeds showed positive correlation with the germination index, but no other hormone. Response of embryo-half seeds to exogenous abscisic acid (ABA) indicates that ABA sensitivity is correlated with whole-seed germinability, which can be explained in part by genotypes of MOTHER OF FT AND TFL (MFT) allele modulating ABA signaling of wheat seeds. These results demonstrate that variation in wheat seed dormancy is attributable to ABA sensitivity of mature seeds, but not to ABA contents in developing seeds.

DOI： 10.1270/jsbbs.19030

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

© 2019 The Authors The Plant Journal © 2019 John Wiley & Sons Ltd In auxin-stimulated roots, production of reactive oxygen species (ROS) via the hormone-induced activation of respiratory burst oxidase homologous NADPH oxidases facilitates lateral root (LR) formation. In this study, in order to verify that ROS can modulate auxin signaling, we examined the involvement of the lipid peroxide-derived agents known as reactive carbonyl species (RCS) in LR formation. When auxin was added to Arabidopsis thaliana roots, the levels of RCS, for example acrolein, 4-hydroxynonenal and crotonaldehyde, were increased prior to LR formation. Addition of the carbonyl scavenger carnosine suppressed auxin-induced LR formation. Addition of RCS to the roots induced the expression of the auxin-responsive DR5 promoter and the TIR1, IAA14, ARF7, LBD16 and PUCHI genes and facilitated LR formation without increasing the endogenous auxin level. DR5 and LBD16 were activated in the LR primordia. The auxin signaling-deficient mutants arf7 arf19 and slr-1 did not respond – and tir1 afb2 appeared to show a poor response – to RCS. When given to the roots RCS promoted the disappearance of the AXR3NT–GUS fusion protein, i.e. the degradation of the auxin/indole-3-acetic acid protein, as did auxin. These results indicate that the auxin-induced production of ROS and their downstream products RCS modulate the auxin signaling pathway in a feed-forward manner. RCS are key agents that connect the ROS signaling and the auxin signaling pathways.

DOI： 10.1111/tpj.14456

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掲載種別：研究論文（学術雑誌）   出版者・発行元：Elsevier BV  

DOI： 10.1016/j.postharvbio.2019.110949

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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/s12870-018-1491-2

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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： 10.1111/pce.13406

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：{MDPI} {AG}  

Cyclic nucleotide-gated channels (CNGCs) have been postulated to contribute significantly in plant development and stress resistance. However, their electrophysiological properties remain poorly understood. Here, we characterized barley CNGC2-3 (HvCNGC2-3) by the two-electrode voltage-clamp technique in the Xenopus laevis oocyte heterologous expression system. Current was not observed in X. laevis oocytes injected with HvCNGC2-3 complementary RNA (cRNA) in a bathing solution containing either Na⁺ or K⁺ solely, even in the presence of 8-bromoadenosine 3',5'-cyclic monophosphate (8Br-cAMP) or 8-bromoguanosine 3',5'-cyclic monophosphate (8Br-cGMP). A weakly voltage-dependent slow hyperpolarization-activated ion current was observed in the co-presence of Na⁺ and K⁺ in the bathing solution and in the presence of 10 µM 8Br-cAMP, but not 8Br-cGMP. Permeability ratios of HvCNGC2-3 to K⁺, Na⁺ and Cl- were determined as 1:0.63:0.03 according to reversal-potential analyses. Amino-acid replacement of the unique ion-selective motif of HvCNGC2-3, AQGL, with the canonical motif, GQGL, resulted in the abolition of the current. This study reports a unique two-ion-dependent activation characteristic of the barley CNGC, HvCNGC2-3.

DOI： 10.3390/plants7030061

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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  

Circumnutation is a plant growth movement in which the tips of axial organs draw a circular orbit. Although it has been studied since the nineteenth century, its mechanism and significance are still unclear. Greened adzuki bean (Vigna angularis) epicotyls exhibited a clockwise circumnutation in the top view with a constant period of 60 min under continuous white light. The bending zone of circumnutation on the epicotyls was always located in the region 1–3 cm below the tip, and its basal end was almost identical to the apical end of the region where the epicotyl had completely elongated. Therefore, epidermal cells that construct the bending zone are constantly turning over with their elongation growth. Since exogenously applied auxin transport inhibitors and indole-3-acetic acid (IAA) impaired circumnutation without any effect on the elongation rate of epicotyls, we attempted to identify the distribution pattern of endogenous auxin. Taking advantage of its large size, we separated the bending zone of epicotyls into two halves along the longitudinal axis, either convex/concave pairs in the plane of curvature of circumnutation or pre-convex/pre-concave pairs perpendicular to the plane. By liquid chromatography–mass spectrometry, we found, for the first time, that IAA and gibberellin A1 were asymmetrically distributed in the pre-convex part in the region 1–2 cm below the tip. This region of epicotyl sections exhibited the highest responsiveness to exogenously applied hormones, and the latent period between the hormone application and the detection of a significant enhancement in elongation was 15 min. Our results suggest that circumnutation in adzuki bean epicotyls with a 60 min period is maintained by differential growth in the bending zone, which reflects the hormonal status 15 min before and which is shifting sequentially in a circumferential direction. Cortical microtubules do not seem to be involved in this regulation.

DOI： 10.1007/s10265-017-0972-y

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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   出版者・発行元：SPRINGER JAPAN KK  

DOI： 10.1007/s10265-017-0969-6

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記述言語：英語   出版者・発行元：OXFORD UNIV PRESS  

DOI： 10.1093/jxb/erw289

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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：NATURE PUBLISHING GROUP  

Global transcriptome studies demonstrated the existence of unique plant responses under combined stress which are otherwise not seen during individual stresses. In order to combat combined stress plants use signaling pathways and 'cross talk' mediated by hormones involved in stress and growth related processes. However, interactions among hormones' pathways in combined stressed plants are not yet known. Here we studied dynamics of different hormones under individual and combined drought and pathogen infection in Arabidopsis thaliana by liquid chromatography-mass spectrometry (LC-MS) based profiling. Our results revealed abscisic acid (ABA) and salicylic acid (SA) as key regulators under individual drought and pathogen stress respectively. Under combined drought and host pathogen stress (DH) we observed non-induced levels of ABA with an upsurge in SA and jasmonic acid (JA) concentrations, underscoring their role in basal tolerance against host pathogen. Under a non-host pathogen interaction with drought (DNH) stressed plants, ABA, SA and JA profiles were similar to those under DH or non-host pathogen alone. We propose that plants use SA/JA dependent signaling during DH stress which antagonize ABA biosynthesis and signaling pathways during early stage of stress. The study provides insights into hormone modulation at different time points during combined stress.

DOI： 10.1038/s41598-017-03907-2

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1093/treephys/tpw134

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：WALTER DE GRUYTER GMBH  

Emerging studies suggest that seaweeds contain phytohormones; however, their chemical entities, biosynthetic pathways, signal transduction mechanisms, and physiological roles are poorly understood. Until recently, it was difficult to conduct comprehensive analysis of phytohormones in seaweeds because of the interfering effects of cellular constituents on fine quantification. In this review, we discuss the details of the latest method allowing simultaneous profiling of multiple phytohormones in red seaweeds, while avoiding the effects of cellular factors. Recent studies have confirmed the presence of indole-3-acetic acid (IAA), N-6-(Delta(2)-isopentenyl) adenine (iP), (+)-abscisic acid (ABA), and salicylic acid, but not of gibberellins and jasmonate, in Pyropia yezoensis and Bangia fuscopurpurea. In addition, an in silico genome-wide homology search indicated that red seaweeds synthesize iP and ABA via pathways similar to those in terrestrial plants, although genes homologous to those involved in IAA biosynthesis in terrestrial plants were not found, suggesting the epiphytic origin of IAA. It is noteworthy that these seaweeds also lack homologues of known factors involved in the perception and signal transduction of IAA, iP, and ABA. Thus, the modes of action of these phytohormones in red seaweeds are unexpectedly dissimilar to those in terrestrial plants.

DOI： 10.1515/bot-2016-0056

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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：TAYLOR & FRANCIS LTD  

Salicylic acid (SA) induces stomatal closure sharing several components with abscisic acid (ABA) and methyl jasmonate (MeJA) signaling. We have previously shown that two guard cell-preferential mitogen-activated protein kinases (MAPKs), MPK9 and MPK12, positively regulate ABA signaling and MeJA signaling in Arabidopsis thaliana. In this study, we examined whether these two MAPKs are involved in SA-induced stomatal closure using genetic mutants and a pharmacological, MAPKK inhibitor. Salicylic acid induced stomatal closure in mpk9 and mpk12 single mutants but not in mpk9 mpk12 double mutants. The MAPKK inhibitor PD98059 inhibited SA-induced stomatal closure in wild-type plants. Salicylic acid induced extracellular reactive oxygen species (ROS) production, intracellular ROS accumulation, and cytosolic alkalization in the mpk9, mpk12, and mpk9 mpk12 mutants. Moreover, SA-activated S-type anion channels in guard cells of wild-type plants but not in guard cells of mpk9 mpk12 double mutants. These results imply that MPK9 and MPK12 are positive regulators of SA signaling in Arabidopsis guard cells.

DOI： 10.1080/09168451.2017.1308244

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記述言語：中国語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Crop Science Society of Japan  

We analyzed the relationship between seedling vigor and phytohormones at the seedling stage in foreign rice “Dunghan Shali” and “Italica Livorno” with vigorous initial growth under low temperature conditions, and Japanese rice “Oboroduki” and “Nipponbare”. The initial growth of “Dunghan Shali” and “Italica Livorno” was superior to that of “Oboroduki” and “Nipponbare” at both 27°C and 12°C. The phytohormone gibberellin supports vigorous initial growth of “Dunghan Shali”. The vigorous initial growth of “Italica Livorno” at 27°C could be induced by the effects of gibberellin since we noted increased expression of OsGA20ox1, a gene that promotes gibberellin biosynthesis. Both “Dunghan Shali” and “Italica Livorno” harbor common mutations in the promoter region of OsGA20ox1. At 12°C, the vigorous initial growth of “Italica Livorno” was because of the increased expression of OsGA20ox1. In “Dunghan Shali”, although the expression of OsGA20ox1 was not high, the level of abscisic acid, which suppresses plant growth, was lower than that in the three other varieties. We conclude that the effect of gibberellin was important for the vigorous initial growth of rice seedlings at 27°C, but a balance of multiple phytohormones may be important for the seedling vigor in rice at 12°C.

DOI： 10.1626/jcs.86.367

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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：OXFORD UNIV PRESS  

The aluminum-activated malate transporter (ALMT) family of proteins transports malate and/or inorganic anions across plant membranes. To demonstrate the possible role of ALMT genes in tomato fruit development, we focused on SlALMT4 and SlALMT5, the two major genes expressed during fruit development. Predicted proteins were classified into clade 2 of the family, many members of which localize to endomembranes. Tissue-specific gene expression was determined using transgenic tomato expressing the beta-glucuronidase reporter gene controlled by their own promoters. Both the genes were expressed in vascular bundles connecting to developing seeds in fruit and in the embryo of mature seeds. Further, SlALMT5 was expressed in embryo in developing seeds in fruit. Subcellular localization of both proteins to the endoplasmic reticulum (ER) was established by transiently expressing the green fluorescent protein fusions in plant protoplasts. SlALMT5 probably localized to other endomembranes as well. Localization of SlALMT5 to the ER was also confirmed by immunoblot analysis. The transport function of both SlALMT proteins was investigated electrophysiologically in Xenopus oocytes. SlALMT5 transported malate and inorganic anions such as nitrate and chloride, but not citrate. SlALMT4 also transported malate, but the results were less consistent perhaps because it did not localize strongly to the plasma membrane. To elucidate the physiological role of SlALMT5 further, we over-expressed SlALMT5 in tomato. Compared with the wild type, overexpressors exhibited higher malate and citrate contents in mature seeds, but not in fruit. We conclude that the malate transport function of SlALMT5 expressed in developing fruit influences the organic acid contents in mature seeds.

DOI： 10.1093/pcp/pcw157

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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  

Emerging work has suggested the existence of phytohormones in seaweeds, although chemical species, endogenous biosynthetic pathways, and signal transduction machineries remain poorly understood. We performed profiling of nine phytohormones with liquid chromatography-mass spectrometry and in silico genome-wide homology search to identify genes involved in biosynthesis and signal transduction of hormones in red algae. It was demonstrated that two Bangiophycean algae, Bangia fuscopurpurea and Pyropia yezoensis, possessed indoleacetic acid (IAA), N-6-(Delta(2)-isopentenyl) adenine (iP), abscisic acid (ABA), and salicylic acid, although trans-zeatin, dihydrozeatin, gibberellin A(1) and A(4), and jasmonate were not detected. Results of genome-wide survey demonstrated that Bangiophycean algae produce iP and ABA via pathways similar to those in terrestrial plants. However, these seaweeds lack homologues of already known factors participating in perception and signal transduction of IAA, iP, ABA and SA, indicating that the action modes of these phytohormones in red seaweeds differ from those elucidated in terrestrial plants. These findings shed lights on evolutional divergence of signal transduction pathways of phytohormones in plants.

DOI： 10.1007/s10811-015-0759-2

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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）   出版者・発行元：OXFORD UNIV PRESS  

Methyl jasmonate (MeJA) induces stomatal closure. It has been shown that stomata of many ABA-insensitive mutants are also insensitive to MeJA, and a low amount of ABA is a prerequisite for the MeJA response. However, the molecular mechanisms of the interaction between ABA and MeJA signaling remain to be elucidated. Here we studied the interplay of signaling of the two hormones in guard cells using the quadruple ABA receptor mutant pyr1 pyl1 pyl2 pyl4 and ABA-activated protein kinase mutants ost1-2 and srk2e. In the quadruple mutant, MeJA-induced stomatal closure, H2O2 production, nitric oxide (NO) production, cytosolic alkalization and plasma membrane Ca2+-permeable current (I-Ca) activation were not impaired. At the same time, the inactivation of the inward-rectifying K+ current was impaired. In contrast to the quadruple mutant, MeJA-induced stomatal closure, H2O2 production, NO production and cytosolic alkalization were impaired in ost1-2 and srk2e as well as in aba2-2, the ABA-deficient mutant. The activation of ICa was also impaired in srk2e. Collectively, these results indicated that OST1 was essential for MeJA-induced stomatal closure, while PYR1, PYL1, PYL2 and PYL4 ABA receptors were not sufficient factors. MeJA did not appear to activate OST1 kinase activity. This implies that OST1 mediates MeJA signaling through an undetectable level of activity or a nonenzymatic action. MeJA induced the expression of an ABA synthesis gene, NCED3, and increased ABA contents only modestly. Taken together with previous reports, this study suggests that MeJA signaling in guard cells is primed by ABA and is not brought about through the pathway mediated by PYR1, PYL1 PYL2 and PYL4.

DOI： 10.1093/pcp/pcw102

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Hordeum vulgare (barley) is an important agricultural crop worldwide. A simple and efficient transformation system is needed to analyze the functions of barley genes and generate lines with improved agronomic traits. Currently, Golden Promise and Igri are the most amenable barley cultivars for stable transformation. Here we evaluated the regeneration ratios and endogenous hormone levels of calli derived from various malting barley cultivars, including Golden Promise, Haruna Nijo, and Morex. We harvested samples not only from immature embryos, but also from different explants of juvenile plants, cotyledons, coleoptiles, and roots. The callus properties differed among genotypes and explant types. Calli derived from the immature embryos of Golden Promise, which showed the highest ratio of regeneration of green shoots, had the highest contents of indoleacetic acid, trans-zeatin, and cis-zeatin. By contrast, calli derived from the cotyledons of Morex and the immature embryos of Haruna Nijo had elevated levels of salicylic acid and abscisic acid, respectively. We thus propose that the former phytohormones are positively associated with the regeneration ability of callus but the later phytohormones are negatively associated.

DOI： 10.1016/j.plaphy.2015.12.005

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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  

Guard cells are indispensable for higher plants because they control gas exchange and water balance to maintain photosynthetic activity. The signaling processes that govern their movement are controlled by several factors, such as abscisic acid (ABA), blue light, pathogen-associated molecular patterns (PAMPs), and carbon dioxide. Herein, we demonstrated that the amino acid glutamate (Glu), a well-known mammalian neurotransmitter, functions as a novel signaling molecule in stomatal closure in both Arabidopsis and fava bean (Vicia faba L.). Pharmacological and electrophysiological analyses provided important clues for the participation of Glu-receptors, Ca2+, and protein phosphorylation during the signaling process. Genetic analyses using Arabidopsis ABA-deficient (aba2-1) and ABA-insensitive (abi1-1 and abi2-1) mutants showed that ABA is not required for Glu signaling. However, loss-of-function of the Arabidopsis gene encoding Slow Anion Channel-Associated 1 (SLAC1) and Calcium-Dependent Protein Kinase 6 (CPK6) impaired the Glu response. Moreover, T-DNA knockout mutations of the Arabidopsis Glu receptor-like gene (GLR), GLR3.5, lost their sensitivity to Glu-dependent stomatal closure. Our results strongly support functional Glu-signaling in stomatal closure and the crucial roles of GLRs in this signaling process.

DOI： 10.1007/s10265-015-0757-0

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掲載種別：研究論文（学術雑誌）   出版者・発行元：MDPI AG  

DOI： 10.3390/proteomes4010001

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掲載種別：研究論文（学術雑誌）  

DOI： 10.1093/jxb/erw071

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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：TAYLOR & FRANCIS LTD  

Isothiocyanates are enzymatically produced from glucosinolates in plants, and allyl isothiocyanate (AITC) induces stomatal closure in Arabidopsis thaliana. In this study, we investigated stomatal responses to AITC in Vicia faba. AITC-induced stomatal closure accompanied by reactive oxygen species (ROS) and NO production, cytosolic alkalization and glutathione (GSH) depletion in V. faba. GSH monoethyl ester induced stomatal reopening and suppressed AITC-induced GSH depletion in guard cells. Exogenous catalase and a peroxidase inhibitor, salicylhydroxamic acid, inhibited AITC-induced stomatal closure, unlike an NAD(P)H oxidase inhibitor, diphenylene iodonium chloride. The peroxidase inhibitor also abolished the AITC-induced ROS production, NO production, and cytosolic alkalization. AITC-induced stomatal closure was suppressed by an NO scavenger, 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, and an agent to acidify cytosol, butyrate. These results indicate that AITC-induced stomatal closure in V. faba as well as in A. thaliana and suggest that AITC signaling in guard cells is conserved in both plants.

DOI： 10.1080/09168451.2015.1045827

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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  

Methyl jasmonate (MeJA) and abscisic acid (ABA) signalling cascades share several signalling components in guard cells. We previously showed that two guard cell-preferential mitogen-activated protein kinases (MAPKs), MPK9 and MPK12, positively regulate ABA signalling in Arabidopsis thaliana. In this study, we examined whether these two MAP kinases function in MeJA signalling using genetic mutants for MPK9 and MPK12 combined with a pharmacological approach. MeJA induced stomatal closure in mpk9-1 and mpk12-1 single mutants as well as wild-type plants, but not in mpk9-1 mpk12-1 double mutants. Consistently, the MAPKK inhibitor PD98059 inhibited the MeJA-induced stomatal closure in wild-type plants. MeJA elicited reactive oxygen species (ROS) production and cytosolic alkalisation in guard cells of the mpk9-1, mpk12-1 and mpk9-1 mpk12-1 mutants, as well in wild-type plants. Furthermore, MeJA triggered elevation of cytosolic Ca2+ concentration ([Ca2+](cyt)) in the mpk9-1 mpk12-1 double mutant as well as wild-type plants. Activation of S-type anion channels by MeJA was impaired in mpk9-1 mpk12-1. Together, these results indicate that MPK9 and MPK12 function upstream of S-type anion channel activation and downstream of ROS production, cytosolic alkalisation and [Ca2+](cyt) elevation in guard cell MeJA signalling, suggesting that MPK9 and MPK12 are key regulators mediating both ABA and MeJA signalling in guard cells.

DOI： 10.1111/plb.12321

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記述言語：英語   出版者・発行元：OXFORD UNIV PRESS  

DOI： 10.1093/jxb/erv264

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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：OXFORD UNIV PRESS  

We recently demonstrated that yeast elicitor (YEL)-induced stomatal closure requires a Ca2+-dependent kinase, CPK6. A Ca2+-independent kinase, Open Stomata 1 (OST1), is involved in stomatal closure induced by various stimuli including ABA. In the present study, we investigated the role of OST1 in YEL-induced stomatal closure in Arabidopsis using a knock-out mutant, ost1-3, and a kinase-deficient mutant, ost1-2. YEL did not induce stomatal closure or activation of guard cell S-type anion channels in the ost1 mutants unlike in wild-type plants. However, YEL did not increase OST1 kinase activity in wild-type guard cells. The YEL-induced stomatal closure and activation of S-type anion channels were also impaired in a gain-of-function mutant of a clade A type 2C protein phosphatase (ABA INSENSITIVE 1), abi1-1C. In the ost1 mutants like in the wild type, YEL induced H2O2 accumulation, activation of non-selective Ca2+-permeable cation (I-Ca) channels and transient elevations in cytosolic free Ca2+ concentration ([Ca2+](cyt)) in guard cells. These results suggest that OST1 kinase is essential for stomatal closure and activation of S-type anion channels induced by YEL and that OST1 is not involved in H2O2 accumulation, I-Ca channel activation or [Ca2+](cyt) elevations in guard cells induced by YEL.

DOI： 10.1093/pcp/pcv051

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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：PUBLIC LIBRARY SCIENCE  

Rice grain yield is predicted to decrease in the future because of an increase in tropospheric ozone concentration. However, the underlying mechanisms are unclear. Here, we investigated the responses to ozone of two rice (Oryza Sativa L.) cultivars, Sasanishiki and Habataki. Sasanishiki showed ozone-induced leaf injury, but no grain yield loss. By contrast, Habataki showed grain yield loss with minimal leaf injury. A QTL associated with grain yield loss caused by ozone was identified in Sasanishiki/Habataki chromosome segment substitution lines and included the ABERRANT PANICLE ORGANIZATION 1 (APO1) gene. The Habataki allele of the APO1 locus in a near-isogenic line also resulted in grain yield loss upon ozone exposure, suggesting APO1 involvement in ozone-induced yield loss. Only a few differences in the APO1 amino acid sequences were detected between the cultivars, but the APO1 transcript level was oppositely regulated by ozone exposure: i.e., it increased in Sasanishiki and decreased in Habataki. Interestingly, the levels of some phytohormones (jasmonic acid, jasmonoyl-L-isoleucine, and abscisic acid) known to be involved in attenuation of ozone-induced leaf injury tended to decrease in Sasanishiki but to increase in Habataki upon ozone exposure. These data indicate that ozone-induced grain yield loss in Habataki is caused by a reduction in the APO1 transcript level through an increase in the levels of phytohormones that reduce leaf damage.

DOI： 10.1371/journal.pone.0123308

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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：MDPI AG  

Biosensors fabricated with whole-cell bacteria appear to be suitable for detecting bioavailability and toxicity effects of the chemical(s) of concern, but they are usually reported to have drawbacks like long response times (ranging from hours to days), narrow dynamic range and instability during long term storage. Our aim is to fabricate a sensitive whole-cell oxidative stress biosensor which has improved properties that address the mentioned weaknesses. In this paper, we report a novel high-throughput whole-cell biosensor fabricated by immobilizing roGFP2 expressing Escherichia coli cells in a k-carrageenan matrix, for the detection of oxidative stress challenged by metalloid compounds. The E. coli roGFP2 oxidative stress biosensor shows high sensitivity towards arsenite and selenite, with wide linear range and low detection limit (arsenite: 1.0 x 10(-3)-1.0 x 10(1) mg center dot L-1, LOD: 2.0 x 10(-4) mg center dot L-1; selenite: 1.0 x 10(-5)-1.0 x 10(2) mg center dot L-1, LOD: 5.8 x 10(-6) mg center dot L-1), short response times (0-9 min), high stability and reproducibility. This research is expected to provide a new direction in performing high-throughput environmental toxicity screening with living bacterial cells which is capable of measuring the bioavailability and toxicity of environmental stressors in a friction of a second.

DOI： 10.3390/s150202354

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担当区分：筆頭著者,　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：PERGAMON-ELSEVIER SCIENCE LTD  

The aquatic ecotoxicity of chemicals involved in the manufacturing process of thin film transistor liquid crystal displays was assessed with a battery of four selected acute toxicity bioassays. We focused on tetramethylammonium hydroxide (TMAH, CAS No. 75-59-2), a widely utilized etchant. The toxicity of TMAH was low when tested in the 72 h-algal growth inhibition test (Pseudokirchneriellia subcapitata, EC50 = 360 mg L-1) and the Microtox (R) test (Vibrio fischeri, IC50 = 6.4 g L-1). In contrast, the 24 h-micro-crustacean immobilization and the 96 h-fish mortality tests showed relatively higher toxicity (Daphnia magna, EC50 = 32 mg L-1 and Oryzias latipes, LC50 = 154 mg L-1). Isobolograrn and mixture toxicity index analyses revealed apparent synergism of the mixture of TMAH and potassium iodide when examined with the D. magna immobilization test. The synergistic action was unique to iodide over other halide salts i.e. fluoride, chloride and bromide. Quaternary ammonium ions with longer alkyl chains such as tetraethylammonium and tetrabutylammonium were more toxic than TMAH in the D. magna immobilization test. (C) 2014 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.chemosphere.2014.07.011

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掲載種別：研究論文（学術雑誌）  

DOI： 10.1093/jxb/erv086

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その他リンク： http://orcid.org/0000-0002-3868-2380

掲載種別：研究論文（学術雑誌）   出版者・発行元：Wiley  

DOI： 10.1111/tpj.12996

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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：ANNUAL REVIEWS  

Guard cells perceive a variety of chemicals produced metabolically in response to abiotic and biotic stresses, integrate the signals into reactive oxygen species and calcium signatures, and convert these signatures into stomatal movements by regulating turgor pressure. Guard cell behaviors in response to such complex signals are critical for plant growth and sustenance in stressful, ever-changing environments. The key open question is how guard cells achieve the signal integration to optimize stomatal aperture. Abscisic acid is responsible for stomatal closure in plants in response to drought, and its signal transduction has been well studied. Other plant hormones and low-molecular-weight compounds function as inducers of stomatal closure and mediators of signaling in guard cells. In this review, we summarize recent advances in research on the diverse stomatal signaling pathways, with specific emphasis on signal integration and signal interaction in guard cell movement.

DOI： 10.1146/annurev-arplant-043014-114707

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Cyclic adenosine 5 &#039;-diphosphoribose (cADPR) cyclic guanosine 3 &#039;,5 &#039;-monophosphate positively function in Ca2+ elevation in methyl jasmonate-induced stomatal closure, cADPR is required for methyl jasmonate-induced ROS accumulation NO production in guard cells

DOI： 10.1111/plb.12175

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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 GMBH, URBAN & FISCHER VERLAG  

In crop species such as wheat, abiotic stresses and preharvest sprouting reduce grain yield and quality. The plant hormone abscisic acid (ABA) plays important roles in abiotic stress tolerance and seed dormancy. In previous studies, we evaluated ABA responsiveness of 67 Aegilops tauschii accessions and their synthetic hexaploid wheat lines, finding wide variation that was due to the D-genome. In this study, quantitative trait locus (QTL) analysis was performed using an F-2 population derived from crosses of highly ABA-responsive and less-responsive synthetic wheat lines. A significant QTL was detected on chromosome 6D, in a similar location to that reported for ABA responsiveness using recombinant inbred lines derived from common wheat cultivars Mironovskaya 808 and Chinese Spring. A comparative map and physiological and expression analyses of the 6D QTL suggested that this locus involved in line differences among wheat synthetics is different from that involved in cultivar differences in common wheat. The common wheat 6D QTL was found to affect seed dormancy and the regulation of cold-responsive/late embryogenesis abundant genes during dehydration. However, in synthetic wheat, we failed to detect any association of ABA responsiveness with abiotic stress tolerance or seed dormancy, at least under our experimental conditions. Development of near-isogenic lines will be important for functional analyses of the synthetic wheat 6D QTL. (C) 2014 Elsevier GmbH. All rights reserved.

DOI： 10.1016/j.jplph.2014.02.003

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担当区分：筆頭著者   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  

CO2 permeability of plasma membrane intrinsic protein 2 (PIP2) aquaporins of Hordeum vulgare L. was investigated. Five PIP2 members were heterologously expressed in Xenopus laevis oocytes. CO2 permeability was determined by decrease of cytosolic pH in CO2-enriched buffer using a hydrogen ion-selective microelectrode. HvPIP2; 1, HvPIP2; 2, HvPIP2; 3 and HvPIP2; 5 facilitated CO2 transport across the oocyte cell membrane. However, HvPIP2; 4 that is highly homologous to HvPIP2; 3 did not. The isoleucine residue at position 254 of HvPIP2; 3 was conserved in PIP2 aquaporins of barley, except HvPIP2; 4, which possesses methionine instead. CO2 permeability was lost by the substitution of the Ile254 of HvPIP2; 3 by methionine, while water permeability was not affected. These results suggest that PIP2 aquaporins are permeable to CO2. and the conserved isoleucine at the end of the E-loop is crucial for CO2 selectivity.

DOI： 10.1093/pcp/pcu003

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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 GMBH, URBAN & FISCHER VERLAG  

The phytohormone abscisic acid (ABA) plays important roles in response to environmental stress as well as in seed maturation and dormancy. In common wheat, quantitative trait loci (QTLs) for ABA responsiveness at the seedling stage have been reported on chromosorries 1B, 2A, 3A, 6D and 7B. In this study, we identified a novel QTL for ABA responsiveness on chromosome 5A using an F-2 population derived from a cross between the common wheat cultivar Chinese Spring (CS) and a chromosome substitution line of CS with chromosome 5A of cultivar Hope (Hope5A). This QTL was found in a similar chromosomal region to previously reported QTLs for drought tolerance and seed dormancy. Physiological characterization of the QTL revealed a small effect on dehydration tolerance and seed dormancy. The rate of water loss from leaves during dehydration was lower, and transcript accumulation of the cold responsive (COR)/late embryogenesis abundant (LEA) genes Wrab18 and Wdhn13 tended to be higher under dehydration stress in F2 individuals carrying the Hope allele of the QTL, which also showed higher ABA responsiveness than the CS allele-carrying individuals. Seed dormancy of individuals carrying the Hope allele also tended to be lower than those carrying the CS allele. Our results suggest that variation in ABA responsiveness among common wheat cultivars is at least partly determined by the 5A QTL, and that this QTL contributes to development of dehydration and preharvest sprouting tolerance. (C) 2013 Elsevier GmbH. All rights reserved.

DOI： 10.1016/j.jplph.2013.10.001

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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 Research Foundation  

The phytohormone abscisic acid (ABA) induces stomatal closure in response to drought stress, leading to reduction of transpirational water loss. A thiol tripeptide glutathione (GSH) is an important regulator of cellular redox homeostasis in plants. Although it has been shown that cellular redox state of guard cells controls ABA-mediated stomatal closure, roles of GSH in guard cell ABA signaling were largely unknown. Recently we demonstrated that GSH functions as a negative regulator of ABA signaling in guard cells. In this study we performed more detailed analyses to reveal how GSH regulates guard cell ABA signaling using the GSH-deficient Arabidopsis mutant cad2-1. The cad2-1 mutant exhibited reduced water loss from rosette leaves. Whole-cell current recording using patch clamp technique revealed that the cad2-1 mutation did not affect ABA regulation of S-type anion channels. We found enhanced activation of Ca2+ permeable channels by hydrogen peroxide (H2O2) in cad2-1 guard cells. The cad2-1 mutant showed enhanced H2O2-induced stomatal closure and significant increase of ROS accumulation in whole leaves in response to ABA. Our findings provide a new understanding of guard cell ABA signaling and a new strategy to improve plant drought tolerance. © 2013 Munemasa, Muroyama, Nagahashi, Nakamura, Mori and Murata.

DOI： 10.3389/fpls.2013.00472

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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 SOC PLANT BIOLOGISTS  

Cytosolic Ca2+ in guard cells plays an important role in stomatal movement responses to environmental stimuli. These cytosolic Ca2+ increases result from Ca2+ influx through Ca2+-permeable channels in the plasma membrane and Ca2+ release from intracellular organelles in guard cells. However, the genes encoding defined plasma membrane Ca2+-permeable channel activity remain unknown in guard cells and, with some exceptions, largely unknown in higher plant cells. Here, we report the identification of two Arabidopsis (Arabidopsis thaliana) cation channel genes, CNGC5 and CNGC6, that are highly expressed in guard cells. Cytosolic application of cyclic GMP (cGMP) and extracellularly applied membrane-permeable 8-Bromoguanosine 39,59-cyclic monophosphate-cGMP both activated hyperpolarization-induced inward-conducting currents in wild-type guard cells using Mg2+ as the main charge carrier. The cGMP-activated currents were strongly blocked by lanthanum and gadolinium and also conducted Ba2+, Ca2+, and Na+ ions. cngc5 cngc6 double mutant guard cells exhibited dramatically impaired cGMP-activated currents. In contrast, mutations in CNGC1, CNGC2, and CNGC20 did not disrupt these cGMP-activated currents. The yellow fluorescent protein-CNGC5 and yellow fluorescent protein-CNGC6 proteins localize in the cell periphery. Cyclic AMP activated modest inward currents in both wild-type and cngc5cngc6 mutant guard cells. Moreover, cngc5 cngc6 double mutant guard cells exhibited functional abscisic acid (ABA)-activated hyperpolarization-dependent Ca2+-permeable cation channel currents, intact ABA-induced stomatal closing responses, and whole-plant stomatal conductance responses to darkness and changes in CO2 concentration. Furthermore, cGMPactivated currents remained intact in the growth controlled by abscisic acid2 and abscisic acid insensitive1 mutants. This research demonstrates that the CNGC5 andCNGC6 genes encode unique cGMP-activated nonselective Ca2+-permeable cation channels in the plasmamembrane ofArabidopsis guard cells.

DOI： 10.1104/pp.113.225045

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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）   出版者・発行元：AMER SOC PLANT BIOLOGISTS  

Abscisic acid (ABA) induces stomatal closure and inhibits light-induced stomatal opening. The mechanisms in these two processes are not necessarily the same. It has been postulated that the ABA receptors involved in opening inhibition are different from those involved in closure induction. Here, we provide evidence that four recently identified ABA receptors (PYRABACTIN RESISTANCE1 [PYR1], PYRABACTIN RESISTANCE-LIKE1 [PYL1], PYL2, and PYL4) are not sufficient for opening inhibition in Arabidopsis (Arabidopsis thaliana). ABA-induced stomatal closure was impaired in the pyr1/pyl1/pyl2/pyl4 quadruple ABA receptor mutant. ABA inhibition of the opening of the mutant's stomata remained intact. ABA did not induce either the production of reactive oxygen species and nitric oxide or the alkalization of the cytosol in the quadruple mutant, in accordance with the closure phenotype. Whole cell patch-clamp analysis of inward-rectifying K+ current in guard cells showed a partial inhibition by ABA, indicating that the ABA sensitivity of the mutant was not fully impaired. ABA substantially inhibited blue light-induced phosphorylation of H+-ATPase in guard cells in both the mutant and the wild type. On the other hand, in a knockout mutant of the SNF1-related protein kinase, srk2e, stomatal opening and closure, reactive oxygen species and nitric oxide production, cytosolic alkalization, inward-rectifying K+ current inactivation, and H+-ATPase phosphorylation were not sensitive to ABA.

DOI： 10.1104/pp.113.223826

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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 SOC PLANT BIOLOGISTS  

Yeast elicitor (YEL) induces stomatal closure that is mediated by a Ca2+-dependent signaling pathway. A Ca2+-dependent protein kinase, CPK6, positively regulates activation of ion channels in abscisic acid and methyl jasmonate signaling, leading to stomatal closure in Arabidopsis (Arabidopsis thaliana). YEL also inhibits light-induced stomatal opening. However, it remains unknown whether CPK6 is involved in induction by YEL of stomatal closure or in inhibition by YEL of light-induced stomatal opening. In this study, we investigated the roles of CPK6 in induction by YEL of stomatal closure and inhibition by YEL of light-induced stomatal opening in Arabidopsis. Disruption of CPK6 gene impaired induction by YEL of stomatal closure and inhibition by YEL of light-induced stomatal opening. Activation by YEL of nonselective Ca2+-permeable cation channels was impaired in cpk6-2 guard cells, and transient elevations elicited by YEL in cytosolic-free Ca2+ concentration were suppressed in cpk6-2 and cpk6-1 guard cells. YEL activated slow anion channels in wild-type guard cells but not in cpk6-2 or cpk6-1 and inhibited inward-rectifying K+ channels in wild-type guard cells but not in cpk6-2 or cpk6-1. The cpk6-2 and cpk6-1 mutations inhibited YEL-induced hydrogen peroxide accumulation in guard cells and apoplast of rosette leaves but did not affect YEL-induced hydrogen peroxide production in the apoplast of rosette leaves. These results suggest that CPK6 positively functions in induction by YEL of stomatal closure and inhibition by YEL of light-induced stomatal opening in Arabidopsis and is a convergent point of signaling pathways for stomatal closure in response to abiotic and biotic stress. © 2013 American Society of Plant Biologists. All Rights Reserved.

DOI： 10.1104/pp.113.224055

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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.jplph.2013.03.011

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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：Japan Society for Bioscience, Biotechnology, and Agrochemistry  

Isothiocyanates, nitriles, and thiocyanates are degradation products of glucosinolates in crucifer plants. In this study, we investigated the stomatal response to allyl isothiocyanate (AITC), 3-butenenitrile (3BN), and ethyl thiocyanate (ESCN) in Arabidopsis. AITC, 3BN, and ESCN induced stomatal closure in the wild type and the atrbohD atrbohF mutant. Stomatal closure was inhibited by catalase and salicylhydroxamic acid (SHAM). The degradation products induced extracellular reactive oxygen species (ROS) production in the rosette leaves, and intracellular ROS accumulation, NO production, and cytosolic free calcium concentration ([Ca 2+ ]cyt) oscillations in guard cells, which were inhibited by SHAM. These results suggest that glucosinolate degradation products induce stomatal closure accompanied by extracellular ROS production mediated by SHAMsensitive peroxidases, intracellular ROS accumulation, and [Ca 2+ ] cyt oscillation in Arabidopsis.

DOI： 10.1271/bbb.120928

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

We report that two mitogen-activated protein kinases (MAPKs), MPK9 and MPK12, positively regulate abscisic acid (ABA)-induced stomatal closure in Arabidopsis thaliana. Yeast elicitor (YEL) induced stomatal closure accompanied by intracellular reactive oxygen species (ROS) accumulation and cytosolic free calcium concentration ([Ca2+]cyt) oscillation. In this study, we examined whether these two MAP kinases are involved in YEL-induced stomatal closure using MAPKK inhibitors, PD98059 and U0126, and MAPK mutants, mpk9, mpk12 and mpk9 mpk12. Both PD98059 and U0126 inhibited YEL-induced stomatal closure. YEL induced stomatal closure in the mpk9 and mpk12 mutants but not in the mpk9 mpk12 mutant, suggesting that a MAPK cascade involving MPK9 and MPK12 functions in guard cell YEL signalling. However, YEL induced extracellular ROS production, intracellular ROS accumulation and cytosolic alkalisation in the mpk9, mpk12 and mpk9 mpk12 mutants. YEL induced [Ca2+]cyt oscillations in both wild type and mpk9 mpk12 mutant. These results suggest that MPK9 and MPK12 function redundantly downstream of extracellular ROS production, intracellular ROS accumulation, cytosolic alkalisation and [Ca2+]cyt oscillation in YEL-induced stomatal closure in Arabidopsis guard cells and are shared with ABA signalling. © 2012 German Botanical Society and The Royal Botanical Society of the Netherlands.

DOI： 10.1111/j.1438-8677.2012.00671.x

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掲載種別：研究論文（学術雑誌）  

Glutathione (GSH) has been shown to negatively regulate methyl jasmonate (MeJA)-induced stomatal closure. We investigated the roles of GSH in MeJA signaling in guard cells using an Arabidopsis mutant, cad2-1, that is deficient in the first GSH biosynthesis enzyme, γ-glutamylcysteine synthetase. MeJA-induced stomatal closure and decreased GSH contents in guard cells. Decreasing GSH by the cad2-1 mutation enhanced MeJA-induced stomatal closure. Depletion of GSH by the cad2-1 mutation or increment of GSH by GSH monoethyl ester did not affect either MeJA-induced production of reactive oxygen species (ROS) or MeJA-induced cytosolic alkalization in guard cells. MeJA and abscisic acid (ABA) induced stomatal closure and GSH depletion in atrbohD and atrbohF single mutants but not in the atrbohD atrbohF double mutant. Moreover, exogenous hydrogen peroxide induced stomatal closure but did not deplete GSH in guard cells. These results indicate that GSH affects MeJA signaling as well as ABA signaling and that GSH negatively regulates a signal component other than ROS production and cytosolic alkalization in MeJA signal pathway of Arabidopsis guard cells. © 2012 Springer Science+Business Media, LLC.

DOI： 10.1007/s00344-012-9291-7

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掲載種別：研究論文（学術雑誌）  

DOI： 10.1111/jipb.12057

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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：Japan Society for Bioscience, Biotechnology, and Agrochemistry  

Salicylic acid (SA), yeast elicitor (YEL), and chitosan (CHT) induced stomatal closure in Arabidopsis wild-type and aba2-2 plants, induced stomatal closure in fluridon-treated wild-type plants, and induced stomatal closure in aos mutants. These results suggest that neither endogenous abscisic acid nor endogenous jasmonic acid is involved in SA-, YEL-, or CHT-induced stomatal closure.

DOI： 10.1271/bbb.120980

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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：TAYLOR & FRANCIS LTD  

Glutathione (GSH) is involved in abscisic acid (ABA)-and methyl jasmonate (MeJA)-induced stomatal closure in Arabidopsis thaliana. In this study, we examined the effects of GSH-decreasing chemicals, p-nitrobenzyl chloride (PNBC), iodomethane (IDM), and ethacrynic acid (EA), on ABA- and MeJA-induced stomatal closure in Arabidopsis. Treatments with PNBC, IDM, and EA decreased GSH contents in guard cells. Depletion of GSH by PNBC and IDM enhanced ABA- and MeJA-induced stomatal closure and inhibition of light-induced stomatal opening by ABA, whereas EA did not enhance either ABA- and MeJA-induced stomatal closure or inhibition of light-induced stomatal opening by ABA. Depletion of GSH did not significantly increase the production of the reactive oxygen species (ROS), cytosolic alkalization, or cytosolic Ca2+ oscillation induced by ABA and MeJA. These results indicate that depletion of GSH enhances ABA- and MeJA-induced stomatal closure without affecting ROS production, cytosolic alkalization, or cytosolic Ca2+ oscillation in guard cells of Arabidopsis.

DOI： 10.1271/bbb.120384

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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：TAYLOR & FRANCIS LTD  

Chitosan (CHT)-induced stomatal closure was inhibited by an MAPKK inhibitor, PD98059, and was impaired in mpk9 mpk12 but not in mpk9 or mpk12. CHT induced the production of reactive oxygen species, cytosolic alkalization, and cytosolic Ca2+ oscillation in mpk9 mpk12. These results suggest that MPK9 and MPK12 are involved in CHT-induced stomatal closure.

DOI： 10.1271/bbb.120228

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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  

Methylglyoxal (MG) is one of the aldehydes accumulated in plants under environmental stress. Cytosolic ascorbate peroxidase (cAPX) plays a key role in the protection of cells from oxidative damage by scavenging reactive oxygen species in higher plants. A cDNA encoding cAPX, named NtcAPX, was isolated from Nicotiana tabacum. We characterized recombinant NtcAPX (rNtcAPX) as a fusion protein with glutathione S-transferase to investigate the effects of MG on APX. NtcAPX consists of 250 amino acids and has a deduced molecular mass of 27.5 kDa. The rNtcAPX showed a higher APX activity. MG treatments resulted in a reduction of APX activity and modifications of amino groups in rNtcAPX with increasing Km for ascorbate. On the contrary, neither NaCl nor cadmium reduced the activity of APX. The present study suggests that inhibition of APX is in part due to the modification of amino acids by MG. (c) 2012 Wiley Periodicals, Inc. J Biochem Mol Toxicol 26:315321, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/jbt.21423

DOI： 10.1002/jbt.21423

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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：TAYLOR & FRANCIS LTD  

Salinity significantly increased trisodium-8-hydroxy-1,3,6-pyrenetrisulphonic acid (PTS) uptake and decreased the K+/Na+ ratio in salt-sensitive rice (Nipponbare) but did not markedly in salt-tolerant rice (Pokkali). Proline and glycinebetaine (betaine) suppressed the increase in PTS uptake and the decrease in the K+/Na+ ratio in Nipponbare, but did not affect PTS uptake or the K+/Na+ ratio in Pokkali.

DOI： 10.1271/bbb.120233

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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）   出版者・発行元：ELSEVIER GMBH, URBAN & FISCHER VERLAG  

Methyl jasmonate (MeJA)-induced stomatal closure is accompanied by the accumulation of hydrogen peroxide (H2O2) in guard cells. In this study, we investigated the roles of catalases (CATs) in MeJA-induced stomatal closure using cat mutants cat2, cat3-1 and cat1 cat3, and the CAT inhibitor, 3-aminotriazole (AT). When assessed with 2',7'-dichlorodihydrofluorescein, the reduction of catalase activity by means of mutations and the inhibitor accumulated higher basal levels of H2O2 in guard cells whereas they did not affect stomatal aperture in the absence of MeJA. In contrast, the cat mutations and the treatment with AT potentiated MeJA-induced stomatal closure and MeJA-induced H2O2 production. These results indicate that CATs negatively regulate H2O2 accumulation in guard cells and suggest that inducible H2O2 production rather than constitutive elevation modulates stomatal apertures in Arabidopsis. (C) 2012 Elsevier GmbH. All rights reserved.

DOI： 10.1016/j.jplph.2012.03.006

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1104/pp.112.195578

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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：TAYLOR & FRANCIS LTD  

We investigated the mechanism of selenium (Se) tolerance using an Arabidopsis thaliana knockout mutant of a sulfate transporter, sultr1;2. Se stress inhibited plant growth, decreased chlorophyll contents, and increased protein oxidation and lipid peroxidation in the wild type, whereas the sultr1;2 mutation mitigated damage of these forms, indicating that sultr1;2 is more tolerant of Se than the wild type is. The accumulation of symplastic Se was suppressed in sultr1;2 as compared to the wild type, and the chemical speciation of Se in the mutant was different from that in the wild type. Regardless of Se stress, the activities of ascorbate peroxidase, catalase, and peroxidase in the mutant were higher than in the wild type, while the activity of superoxide dismutase in the mutant was the same as in the wild type. These results suggest that the sultr1;2 mutation confers Se tolerance on Arabidopsis by decreasing symplastic Se and maintaining antioxidant enzyme activities.

DOI： 10.1271/bbb.111000

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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：OXFORD UNIV PRESS  

An abscisic acid (ABA)-insensitive Vicia faba mutant, fia (fava bean impaired in ABA-induced stomatal closure) had previously been isolated. In this study, it was investigated how FIA functions in ABA signalling in guard cells of Vicia faba. Unlike ABA, methyl jasmonate (MeJA), H2O2, and nitric oxide (NO) induced stomatal closure in the fia mutant. ABA did not induce production of either reactive oxygen species or NO in the mutant. Moreover, ABA did not suppress inward-rectifying K+ (K-in) currents or activate ABA-activated protein kinase (AAPK) in mutant guard cells. These results suggest that FIA functions as an early signal component upstream of AAPK activation in ABA signalling but does not function in MeJA signalling in guard cells of Vicia faba.

DOI： 10.1093/jxb/err369

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担当区分：責任著者   掲載種別：研究論文（学術雑誌）  

Reactive oxygen species (ROS), including hydrogen peroxide (H 2 O 2 ), are among the important second messengers in abscisic acid (ABA) signaling in guard cells. In this study, to investigate specific roles of H 2 O 2 in ABA signaling in guard cells, we examined the effects of mutations in the guard cell-expressed catalase (CAT) genes, CAT1 and CAT3, and of the CAT inhibitor 3-aminotriazole (AT) on stomatal movement. The cat3 and cat1 cat3 mutations significantly reduced CAT activities, leading to higher basal level of H 2 O 2 in guard cells, when assessed by 2&#039;,7&#039;-dichlorodihydrofluorescein, whereas they did not affect stomatal aperture size under non-stressed condition. In addition, AT-treatment at concentrations that abolish CAT activities, showed trivial affect on stomatal aperture size, while basal H 2 O 2 level increased extensively. In contrast, cat mutations and AT-treatment potentiated ABA-induced stomatal closure. Inducible ROS production triggered by ABA was observed in these mutants and wild type as well as in AT-treated guard cells. These results suggest that ABA-inducible cytosolic H 2 O 2 elevation functions in ABA-induced stomatal closure, while constitutive increase of H 2 O 2 do not cause stomatal closure. © 2011 Elsevier GmbH.

DOI： 10.1016/j.jplph.2011.05.006

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掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.jplph.2011.06.002

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掲載種別：研究論文（学術雑誌）  

DOI： 10.1111/j.1365-3040.2011.02385.x

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掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.jplph.2011.05.004

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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）   出版者・発行元：Japan Society for Bioscience, Biotechnology, and Agrochemistry  

We investigated the roles of catalase (CAT) in abscisic acid (ABA)-induced stomatal closure using a cat2 mutant and an inhibitor of CAT, 3-aminotriazole (AT). Constitutive reactive oxygen species (ROS) accumulation due to the CAT2 mutation and AT treatment did not affect stomatal aperture in the absence of ABA, whereas ABA-induced stomatal closure, ROS production, and [Ca 2+ ] cyt oscillation were enhanced.

DOI： 10.1271/bbb.110344

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Barley seeds were exposed to outer space for 13 months in a vented metal container without a climate control system to assess the risk of physiological and genetic mutation during long-term storage in space. The space-stored seeds (S0 generation), with an 82% germination rate in 50 seeds, lost about 20% of their weight after the exposure. The germinated seeds showed normal growth, heading, and ripening. The harvested seeds (S1 generation) also germinated and reproduced (S2 generation) as did the ground-stored seeds. The culm length, ear length, number of seed, grain weight, and fertility of the plants from the space-stored seeds were not significantly different from those of the ground-stored seeds in each of the S0 and S1 generation. Furthermore, the S1 and S2 space-stored seeds respectively showed similar β-glucan content to those of the ground-stored seeds. Amplified fragment length polymorphism analysis with 16 primer combinations showed no specific fragment that appears or disappears significantly in the DNA isolated from the barley grown from the space-stored seeds. Though these data are derived from nine S0 space-stored seeds in a single exposure experiment, the results demonstrate the preservation of barley seeds in outer space for 13 months without phenotypic or genotypic changes and with healthy and vigorous growth in space. © 2011 COSPAR. Published by Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.asr.2011.05.017

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掲載種別：研究論文（学術雑誌）  

DOI： 10.4161/psb.6.7.15439

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DOI： 10.1104/pp.111.172254

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DOI： 10.1111/j.1365-3040.2010.02253.x

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DOI： 10.1104/pp.110.162750

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担当区分：筆頭著者   掲載種別：研究論文（学術雑誌）  

DOI： 10.1007/s10265-011-0435-9

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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：Japan Society for Bioscience, Biotechnology, and Agrochemistry  

We examined the involvement of intracellular glutathione (GSH) in methyl jasmonate (MeJA) signaling. The chlorina1-1 (ch1-1) mutation decreased GSH in guard cells and narrowed the stomatal aperture. GSH monoethyl ester increased intracellular GSH, diminishing this phenotype. GSH did not affect MeJA-induced reactive oxygen species production or cytosolic Ca 2+ oscillation, suggesting that GSH modulates MeJA signaling downstream of production and oscillation.

DOI： 10.1271/bbb.100513

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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：Japan Society for Bioscience, Biotechnology, and Agrochemistry  

Methylglyoxal (MG) is one of the aldehydes that accumulate in plants under environmental stress. Glutathione S-transferases (GSTs) play important roles, including detoxification, in the stress tolerance systems of plants. To determine the effects of MG, we characterized recombinant GST. MG decreased GST activity and thiol contents with increasing K m . GST can serve as a target of MG modification, which is suppressed by application of reduced glutathione.

DOI： 10.1271/bbb.100393

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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：Oxford University Press  

DOI： 10.1093/pcp/pcq145

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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：Oxford University Press  

DOI： 10.1093/pcp/pcq131

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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：TRIVENI ENTERPRISES  

Tanning industries are one of toe main economic activities in Bangladesh. It has been well documented that wastewater discharged from tanneries without appropriate treatment results in detrimental effects on the ecosystem. No ecotoxicity evaluation of any aquatic environment in Bangladesh has been conducted so far In this study a battery of toxicity bioassays and chemical analysis were carried out from water samples obtained from three sampling points: upstream from discharging site on River Buriganga (S1), raw wastewater effluent (S2), and downstream the discharging sluice gate (S3), in the Hazaribagh tannery area of Dhaka City, Bangladesh. While Si and S3 water samples did not show significant toxicity in the bioassays tested, S2 exhibited high acute toxicity to the bacterium Vibrio fischeri (15-min Microtox (R) test, EC(50) = 9.8%), the higher plant Lactuca sativa (5-day root elongation inhibition test, EC(50) = 14.2%), and the microcrustacean Daphnia magna (24-hour mobility test, EC(50) = 31.5%). The results suggested that the raw wastewater effluent had detrimental effects on broad spectrum of organisms in the aquatic ecosystem and bacterium was the most sensitive. The chemical analysis revealed that sample S2 contained an extremely high concentration of chromium (47 g l(-1)). Additionally, microbiological analysis indicated that the sampling area is impacted by fecal pollution, increasing the environmental health risk for its inhabitants.

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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：MDPI AG  

A highly specific, high throughput-amenable bacterial biosensor for chemically induced cellular oxidation was developed using constitutively expressed redox-sensitive green fluorescent protein roGFP2 in E. coli (E. coli-roGFP2). Disulfide formation between two key cysteine residues of roGFP2 was assessed using a double-wavelength ratiometric approach. This study demonstrates that only a few minutes were required to detect oxidation using E. coli-roGFP2, in contrast to conventional bacterial oxidative stress sensors. Cellular oxidation induced by hydrogen peroxide, menadione, sodium selenite, zinc pyrithione, triphenyltin and naphthalene became detectable after 10 seconds and reached the maxima between 80 to 210 seconds, contrary to Cd(2+), Cu(2+), Pb(2+), Zn(2+) and sodium arsenite, which induced the oxidation maximum immediately. The lowest observable effect concentrations (in ppm) were determined as 1.0 x 10(-7) (arsenite), 1.0 x 10(-4) (naphthalene), 1.0 x 10(-4) (Cu(2+)), 3.8 x 10(-4) (H(2)O(2)), 1.0 x 10(-3) (Cd(2+)), 1.0 x 10(-3) (Zn(2+)), 1.0 x 10(-2) (menadione), 1.0 (triphenyltin), 1.56 (zinc pyrithione), 3.1 (selenite) and 6.3 (Pb(2+)), respectively. Heavy metal-induced oxidation showed unclear response patterns, whereas concentration-dependent sigmoid curves were observed for other compounds. In vivo GSH content and in vitro roGFP2 oxidation assays together with E. coli-roGFP2 results suggest that roGFP2 is sensitive to redox potential change and thiol modification induced by environmental stressors. Based on redox-sensitive technology, E. coli-roGFP2 provides a fast comprehensive detection system for toxicants that induce cellular oxidation.

DOI： 10.3390/s100706290

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担当区分：筆頭著者   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  

Plant stomata limit both carbon dioxide uptake and water loss; hence, stomatal aperture is carefully set as the environment fluctuates. Aperture area is known to be regulated in part by ion transport, but few of the transporters have been characterized. Here we report that AtALMT12 (At4g17970), a homolog of the aluminum-activated malate transporter (ALMT) of wheat, is expressed in guard cells of Arabidopsis thaliana. Loss-of-function mutations in AtALMT12 impair stomatal closure induced by ABA, calcium and darkness, but do not abolish either the rapidly activated or the slowly activated anion currents previously identified as being important for stomatal closure. Expressed in Xenopus oocytes, AtALMT12 facilitates chloride and nitrate currents, but not those of organic solutes. Therefore, we conclude that AtALMT12 is a novel class of anion transporter involved in stomatal closure.

DOI： 10.1093/pcp/pcq016

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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：Oxford University Press  

DOI： 10.1093/pcp/pcq001

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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：Japan Society for Bioscience, Biotechnology, and Agrochemistry  

Chitosan induced stomatal closure in wild type-plants and NADPH oxidase knock-out mutants (atrbohD atrbohF), and reactive oxygen species (ROS) production in wild-type guard cells. Closure and production were completely abolished by catalase and a peroxidase inhibitor. These results indicate that chitosan induces ROS production mediated by peroxidase, resulting in stomatal closure.

DOI： 10.1271/bbb.100340

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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：TAYLOR & FRANCIS LTD  

The application of exogenous proline and glycinebetaine (betaine) confers salt tolerance on plants under salt stress. The effects of exogenous proline and betaine on apoplastic How in rice plants under saline conditions were investigated using trisodium-8-hydroxy-1,3,6-pyrenetrisulphonic acid (PTS), an apoplastic tracer. Rice plants took up more PTS under light conditions than under dark conditions. Salt stress increased PTS uptake and Na+ content of rice leaves, but did not affect K+ content, resulting in a lower K+/Na+ ratio. Addition of proline or betaine to the saline medium suppressed Na+-induced PTS uptake and Na+ accumulation, while the K+ content was slightly increased, which led to a high K+/Na+ ratio under saline conditions. These results suggest that exogenous proline and betaine suppressed Na+-enhanced apoplastic flow to reduce Na+ uptake in rice plants.

DOI： 10.1271/bbb.90244

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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：OXFORD UNIV PRESS  

Thioglucoside glucohydrolase (myrosinase), TGG1, is a strikingly abundant protein in Arabidopsis guard cells. We investigated responses of tgg1-3, tgg2-1 and tgg1-3 tgg2-1 mutants to abscisic acid (ABA) and methyl jasmonate (MeJA) to clarify whether two myrosinases, TGG1 and TGG2, function during stomatal closure. ABA, MeJA and H2O2 induced stomatal closure in wild type, tgg1-3 and tgg2-1, but failed to induce stomatal closure in tgg1-3 tgg2-1. All mutants and wild type showed Ca-2-induced stomatal closure and ABA-induced reactive oxygen species (ROS)production. A model is discussed in which two myrosinases redundantly function downstream of ROS production and upstream of cytosolic Ca-2 elevation in ABA and MeJA signaling in guard cells.

DOI： 10.1093/pcp/pcp066

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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：Landes Bioscience  

Intracellular components in methyl jasmonate (MeJA) signaling remain largely unknown, to compare those in well-understood abscisic acid (ABA) signaling. We have reported that nitric oxide (NO) is a signaling component in MeJA-induced stomatal closure, as well as ABA-induced stomatal closure in the previous study. To gain further information about the role of NO in the guard cell signaling, NO production was examined in an ABA- and MeJA-insensitive Arabidopsis mutant, rcn1. Neither MeJA nor ABA induced NO production in rcn1 guard cells. Our data suggest that NO functions downstream of the branch point of MeJA and ABA signaling in Arabidopsis guard cells. ©2009 Landes Bioscience.

DOI： 10.4161/psb.4.2.7537

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出版者・発行元：日本植物生理学会  

植物において、様々な防御応答を司るジャスモン酸メチル（MeJA）は、アブシジン酸（ABA）と同様に気孔閉口を誘導する。MeJAが誘導する気孔閉口シグナル伝達には様々な因子が関与していることが報告されている。シロイヌナズナのタンパク質脱リン酸化酵素2A（PP2A）のAサブユニットの1つであるRCN1は、根におけるオーキシンシグナル及び孔辺細胞におけるABAシグナルに関与することが知られている。以前の我々の研究は、RCN1が、孔辺細胞におけるMeJAシグナルにも関与しており、正の調節因子として機能することを示唆した。RCN1は、MeJAによる孔辺細胞内の活性酸素種の産生、内向きカリウムイオンチャネル活性の制御に必須である。<br> 今回我々は、MeJAによる孔辺細胞内の一酸化窒素産生やカルシウムイオンチャネル及びアニオンチャネル活性の制御機構におけるRCN1の役割を明らかにする為に研究を行った。ここで得られた知見は、シロイヌナズナ孔辺細胞におけるMeJAシグナリングの新たなモデルを提唱する。

DOI： 10.14841/jspp.2009.0.0451.0

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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：TAYLOR & FRANCIS LTD  

We investigated the role of glutathione (GSH) in stomatal movements using a GSH deficient mutant, chlorinal-1 (ch1-1). Guard cells of ch1-1 mutants accumulated less GSH than wild types did. Light induced stomatal opening in ch1-1 and wild-type plants. Abscisic acid (ABA) induced stomatal closure in ch1-1 mutants more than wild types without enhanced reactive oxygen species (ROS) production. Therefore, GSH functioned downstream of ROS production in the ABA signaling cascade.

DOI： 10.1271/bbb.80407

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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：OXFORD UNIV PRESS  

Methyl jasmonate (MeJA) as well as abscisic acid (ABA) induces stomatal closure with their signal crosstalk. We investigated the function of a regulatory A subunit of protein phosphatase 2A, RCN1, in MeJA signaling. Both MeJA and ABA failed to induce stomatal closure in Arabidopsis rcn1 knockout mutants unlike in wild-type plants. Neither MeJA nor ABA induced reactive oxygen species (ROS) production and suppressed inward-rectifying potassium channel activities in rcn1 mutants but not in wild-type plants. These results suggest that RCN1 functions upstream of ROS production and downstream of the branch point of MeJA signaling and ABA signaling in Arabidopsis guard cells.

DOI： 10.1093/pcp/pcn106

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：PUBLIC LIBRARY SCIENCE  

Abscisic acid (ABA) signal transduction has been proposed to utilize cytosolic Ca2+ in guard cell ion channel regulation. However, genetic mutants in Ca2+ sensors that impair guard cell or plant ion channel signaling responses have not been identified, and whether Ca2+-independent ABA signaling mechanisms suffice for a full response remains unclear. Calcium-dependent protein kinases (CDPKs) have been proposed to contribute to central signal transduction responses in plants. However, no Arabidopsis CDPK gene disruption mutant phenotype has been reported to date, likely due to overlapping redundancies in CDPKs. Two Arabidopsis guard cell-expressed CDPK genes, CPK3 and CPK6, showed gene disruption phenotypes. ABA and Ca2+ activation of slow-type anion channels and, interestingly, ABA activation of plasma membrane Ca2+-permeable channels were impaired in independent alleles of single and double cpk3cpk6 mutant guard cells. Furthermore, ABA- and Ca2+-induced stomatal closing were partially impaired in these cpk3cpk6 mutant alleles. However, rapid-type anion channel current activity was not affected, consistent with the partial stomatal closing response in double mutants via a proposed branched signaling network. Imposed Ca2+ oscillation experiments revealed that Ca2+-reactive stomatal closure was reduced in CDPK double mutant plants. However, long-lasting Ca2+-programmed stomatal closure was not impaired, providing genetic evidence for a functional separation of these two modes of Ca2+-induced stomatal closing. Our findings show important functions of the CPK6 and CPK3 CDPKs in guard cell ion channel regulation and provide genetic evidence for calcium sensors that transduce stomatal ABA signaling.

DOI： 10.1371/journal.pbio.0040327

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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：VERLAG Z NATURFORSCH  

Protein kinases are involved in signal transduction for environmental stress responses. In response to drought and salinity, a 48-kDa protein kinase (AAPK; abscisic acid-activated protein kinase (AAPK) in guard cells is activated by abscisic acid (ABA) and phosphorylates several targets such as the carboxy-terminus of inward-rectifying K+ channel and heterogeneous mRNA binding protein to adopt to the changing environment. The AAPK expressed specifically in guard cells, and recombinant AAPK was phosphorylated only with the extract from ABA-treated guard cells but not from untreated cells. This indicates the presence of an AAPK kinase (AAPKK), which is activated by ABA and phosphorylates AAPK preceding the activation of AAPK. Both AAPK and AAPKK are involved in the protein kinase cascade for the rapid ABA-signaling.

DOI： 10.1515/znc-2005-9-1017

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担当区分：筆頭著者   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 PLANT BIOLOGISTS  

DOI： 10.1104/pp.104.042069

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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：NATURE PUBLISHING GROUP  

Reactive oxygen species (ROS) have been proposed to function as second messengers in abscisic acid (ABA) signaling in guard cells. However, the question whether ROS production is indeed required for ABA signal transduction in vivo has not yet been addressed, and the molecular mechanisms mediating ROS production during ABA signaling remain unknown. Here, we report identification of two partially redundant Arabidopsis guard cell-expressed NADPH oxidase catalytic subunit genes, AtrbohD and AtrbohF, in which gene disruption impairs ABA signaling. atrbohD/F double mutations impair ABA-induced stomatal closing, ABA promotion of ROS production, ABA-induced cytosolic Ca(2+) increases and ABA- activation of plasma membrane Ca(2+)-permeable channels in guard cells. Exogenous H(2)O(2) rescues both Ca(2+) channel activation and stomatal closing in atrbohD/F. ABA inhibition of seed germination and root elongation are impaired in atrbohD/F, suggesting more general roles for ROS and NADPH oxidases in ABA signaling. These data provide direct molecular genetic and cell biological evidence that ROS are rate-limiting second messengers in ABA signaling, and that the AtrbohD and AtrbohF NADPH oxidases function in guard cell ABA signal transduction.

DOI： 10.1093/emboj/cdg277

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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 SOC PLANT BIOLOGISTS  

A variety of stimuli, such as abscisic acid (ABA), reactive oxygen species (ROS), and elicitors of plant defense reactions, have been shown to induce stomatal closure. Our study addresses commonalities in the signaling pathways that these stimuli trigger. A recent report showed that both ABA and ROS stimulate an NADPH-dependent, hyperpolarization-activated Ca2+ influx current in Arabidopsis guard cells termed "I-Ca" (Z.M. Pei, Y. Murata, G. Benning, S. Thomine, B. Klusener, G.J. Allen, E. Grill, J.I. Schroeder, Nature [2002] 406: 731-734). We found that yeast (Saccharomyces cerevisiae) elicitor and chitosan, both elicitors of plant defense responses, also activate this current and activation requires cytosolic NAD(P)H. These elicitors also induced elevations in the concentration of free cytosolic calcium ([Ca2+](cyt)) and stomatal closure in guard cells. ABA and ROS elicited [Ca2+](cyt), oscillations in guard cells only when extracellular Ca2+ was present. In a 5 mM KCl extracellular buffer, 45% of guard cells exhibited spontaneous [Ca2+](cyt) oscillations that differed in their kinetic properties from ABA-induced Ca2+ increases. These spontaneous [Ca2+](cyt) oscillations also required the availability of extracellular Ca2+ and depended on the extracellular potassium concentration. Interestingly, when ABA was applied to spontaneously oscillating cells, ABA caused cessation of [Ca2+](cyt), elevations in 62 of 101 cells, revealing a new mode of ABA signaling. These data show that fungal elicitors activate a shared branch with ABA in the stress signal transduction pathway in guard cells that activates plasma membrane I-Ca channels and support a requirement for extracellular Ca2+ for elicitor and ABA signaling, as well as for cellular [Ca2+](cyt) oscillation maintenance.

DOI： 10.1104/pp.012187

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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：TAYLOR & FRANCIS LTD  

beta-Phenylethylamine (PEA) induced an increase in cytosolic free calcium ion concentration ([Ca2+](c)) in Saccharomyces cereviseae cells monitored with transgenic aequorin, a Ca2+-dependent photoprotein. The PEA-induced [Ca2+](c), increase was dependent on the concentrations of PEA applied, and the Ca2+ mostly originated from an extracellular source. Preceding the Ca2+ influx, H2O2 was generated in the cells by the addition of PEA. Externally added H2O2 also induced a [Ca2+](c) increase. These results suggest that PEA induces the [Ca2+](c) increase via H2O2 generation. The PEA-induced [Ca2+](c) increase occurred in the mid1 mutant with a slightly smaller peak than in the wild-type strain, indicating that Mid1, a stretch-activated nonselective cation channel, may not be mainly involved in the PEA-induced Ca2+ influx. When PEA was applied, the MATa mid1 mutant was rescued from a-factor-induced death in a Ca2+-limited medium, suggesting that the PEA-induced [Ca2+](c) increase can reinforce calcium signaling in the mating pheromone response pathway.

DOI： 10.1271/bbb.66.1069

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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 SOC PLANT BIOLOGISTS  

DOI： 10.1105/tpc.13.11.2513

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担当区分：筆頭著者   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  

Salicylic acid (SA), the known mediator of systemic acquired resistance, induced stomatal closure of Vicia faba L. Application of SA to the epidermal peels evoked an elevation of chemiluminescence of Cripridina lucigenin-derived chemiluminescent reagent (CLA) which is sensitive to superoxide anion (O-2(radical anion)). The SA-induced generation of chemiluminescence was suppressed by O-2(radical anion)-specific scavengers superoxide dismutase (SOD) and 4,5-dihydroxy-1,3-benzenedisulfonic acid (Tiron). These results suggest that O-2(radical anion) was generated in epidermal peels by SA-treatment. A peroxidase inhibitor salicylhydroxamic acid (SHAM) inhibited guaiacol peroxidase activity and suppressed the SA-induced CLA chemiluminescence in the epidermal peels, suggesting that O-2(radical anion) generation occurred by the peroxidase-catalyzed reaction as proposed for SA-treated tobacco cell suspension culture [Kawano et al. (1998) Plant Cell Physiol. 39: 721]. SOD, Tiron or SHAM suppressed the SA-induced stomatal closure. Moreover, application of superoxide-generating system also induced stomatal closure. These results support the concept of involvement of reactive oxygen species in signal transduction in SA-induced stomatal closure.

DOI： 10.1093/pcp/pce176

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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：OXFORD UNIV PRESS  

Using Ca2+-dependent photoprotein aequorin-transformed Arabidopsis thaliana, sugar-induced increase in cytosolic free Ca2+ concentration ([Ca2+](cyt)) was investigated by luminescence imaging technique. When 0.1 M sucrose was fed to roots of autotrophically grown intact whole plants whose roots had been incubated overnight with coelenterazine to reconstitute aequorin systemically, strong and transient (within 20 s) luminescence was observed in the roots; that luminescence was followed by weak luminescence moving from the lower leaves to the upper leaves. The moving rate of luminescence was roughly comparable to that of [C-14]sucrose. Application of 0.1 M glucose or fructose induced transient luminescence in excised leaves. No such luminescence was observed in heterotrophically grown (with sucrose) whole plants or in excised tissues. mRNA levels of sucrose-H+ symporter genes AtSUC1 and AtSUC2 were higher in autotrophic plants than in heterotrophic plants. These results indicate that influx of transported sucrose together with H+ into the mesophyll cells of autotrophic plants may depolarize the membrane potential, and subsequently activate a voltage-gated Ca2+ channel on the plasma membrane, resulting in a [Ca2+](cyt) increase. The [Ca2+](cyt) increase might initiate Ca2+ signaling leading to the expression of genes related to biosynthesis of storage carbohydrates. Hexoses, when applied, might also be involved in the [Ca2+](cyt) increase mediated by monosaccharide-H+ co-transporters.

DOI： 10.1093/pcp/pce150

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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：PHYCOLOGICAL SOC AMER INC  

The cytoplasm around a wound made in the multinucleate unicellular green alga Ventricaria ventricosa (J. Agardh) Olsen ct West formed an aggregation-ring surrounding the wound immediately after injury. A contraction of the ring then brought about wound healing in culture medium containing Ca2+. Involvement of a calcium-dependent protein kinase (CDPK) as a regulator of wound healing was examined using an anti-Dunaliella tertiolecta CDPK antibody. A 52-kDa protein cross-reacting with the antibody was detected by Western blotting. Protein kinases of 60 kDa and 52 kDa, which were markedly activated by Ca2+, and a 40-kDa Ca2+-independent protein kinase were detected by an in-gel protein kinase assay using myelin basic protein as the substrate. A 52-kDa band with Ca2+-dependent protein kinase activity was immunoprecipitated from the cytoplasmic extract, indicating that these 52-kDa proteins are identical and possess CDPK activity. Microscopic observation showed that the contraction of the aggregation ring was suppressed by application of the anti-CDPK to the culture medium. A protein kinase inhibitor, K-252a, and the calmodulin inhibitors, calmidazolium and compound 48/80, which inhibit CDPK activity, also suppressed the contraction of the aggregation-ring, Immunofluorescence microscopy showed a similar distribution of 52-kDa CDPK to the distribution of f-actin, which was randomly distributed in an intact cell and formed a bundle during wound healing. Further, f-actin was not recruited after injury in the presence of the antibody to CDPK. These results suggest that the 52-kDa CDPK functions as a Ca2+ receptor in wound healing and simultaneously participates in the organization and contraction of f-actin to heal the wound.

DOI： 10.1046/j.1529-8817.2000.00050.x

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：JAPANESE SOC PLANT PHYSIOLOGISTS  

A 48-kDa protein kinase was detected in Vicia faba guard cell protoplasts by an in-gel protein kinase assay using a recombinant peptide (KAT1C) of the carboxyl-terminus of an inward-rectifying voltage-dependent K+ channel cloned from Arabidopsis thaliana, KAT1, This protein kinase (ABR* kinase) was activated by pretreatment of guard cell protoplasts with ABA, but not by pretreatment with IAA, 2,4-D, kinetin or GA(3). The activation of ABR* kinase was dependent on the time and concentration of ABA, The kinase activity was sensitive to staurosporine and K-252a, protein kinase inhibitors, and insensitive to Ca2+, No ABR* kinase activity was detected in mesophyll cell protoplasts, These characteristics of ABR* kinase are consistent with those of an ABA-responsive protein kinase (ABR kinase) reported previously [Mori and Mute (1997), Plant Physiol, 113: 833], These results indicate that ABR* kinase phosphorylates the inward-rectifying K+ channel in response to treatment of stomatal guard cells with ABA, The data reported here provide evidence that this ABA-responsive protein kinase may promote ABA signaling by directly phosphorylating guard cell ion channels.

DOI： 10.1093/pcp/pcd003

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掲載種別：研究論文（学術雑誌）  

DOI： 10.1046/j.1529-8817.2000.00071.x

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：社団法人日本農芸化学会  

Cytosolic free calcium ion concentration ([Ca^<2+>]_<cyt>) after a salicylic acid (SA)-stimulus was monitored in cells of the yeast Saccharomyces cerevisiae expressing apoaequorin, which constitutes a Ca^<2+>-sensitive luminescent protein, aequorin, when combined with coelenterazine. SA induced a transient [Ca^<2+>]_<cyt> elevation that was dependent on the concentration of SA and pH of the SA solution. The SA-induced [Ca^<2+>]_<cyt> elevation was not reduced in Ca^<2+>-deficient medium, suggesting that Ca^<2+> was mobilized from an intracellular Ca^<2+> store (s). Benzoic acid, butyric acid and sorbic acid did not induced a [Ca^<2+>]_<cyt> elevation.

DOI： 10.1271/bbb.62.986

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担当区分：筆頭著者   掲載種別：研究論文（学術雑誌）  

DOI： 10.1104/pp.113.3.833

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担当区分：筆頭著者,　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：Japanese Society of Phycology  

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記述言語：日本語  

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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）  

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DOI： 10.1002/9781118764374.ch3

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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/kagakutoseibutsu.46.440

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その他リンク： https://jlc.jst.go.jp/DN/JALC/00316431291?from=CiNii

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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   出版者・発行元：Japanese Society of Plant Physiologists  

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その他リンク： https://projects.repo.nii.ac.jp/?action=repository_uri&item_id=183810

記述言語：英語  

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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/kagakutoseibutsu1962.36.66

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その他リンク： https://jlc.jst.go.jp/DN/JALC/00050986040?from=CiNii

記述言語：日本語  

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記述言語：英語  

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記述言語：日本語  

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開催地：名古屋  

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開催年月日： 2019年3月13日 - 2019年3月15日

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開催年月日： 2019年3月13日 - 2019年3月15日

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開催年月日： 2019年3月13日 - 2019年3月15日

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開催年月日： 2018年3月19日

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開催地：Changchun, Jilin, China  

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開催年月日： 2018年3月15日 - 2018年3月18日

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開催年月日： 2018年1月25日

記述言語：日本語   会議種別：シンポジウム・ワークショップ パネル（指名）  

開催地：岡山県倉敷市  

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開催地：Madison, Wisconsin, USA  

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記述言語：日本語   会議種別：シンポジウム・ワークショップ パネル（指名）  

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