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論文
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Asano, Tomoya ; Masuda, Daisuke ; Yasuda, Michiko ; Nakashita, Hideo ; Kudo, Toshiaki ; Kimura, Makoto ; Yamaguchi, Kazuo ; Nishiuchi, Takumi
概要:
金沢大学学際科学実験センター遺伝子研究施設<br />Trichothecenes are a closely related family of phytotoxins that are produced by phytopathogen
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ic fungi. In Arabidopsis, expression of AtNFXL1, a homologue of the putative human transcription repressor NF-X1, was significantly induced by application of type A trichothecenes, such as T-2 toxin. An atnfxl1 mutant growing on medium lacking trichothecenes showed no phenotype, whereas a hypersensitivity phenotype was observed in T-2 toxin-treated atnfxl1 mutant plants. Microarray analysis indicated that several defense-related genes (i.e. WRKYs, NBS-LRRs, EDS5, ICS1, etc.) were upregulated in T-2 toxin-treated atnfxl1 mutants compared with wild-type plants. In addition, enhanced salicylic acid (SA) accumulation was observed in T-2 toxin-treated atnfxl1 mutants, which suggests that AtNFXL1 functions as a negative regulator of these defense-related genes via an SA-dependent signaling pathway. We also found that expression of AtNFXL1 was induced by SA and flg22 treatment. Moreover, the atnfxl1 mutant was less susceptible to a compatible phytopathogen, Pseudomonas syringae pv. tomato strain DC3000 (Pst DC3000). Taken together, these results indicate that AtNFXL1 plays an important role in the trichothecene response, as well as the general defense response in Arabidopsis. © 2007 The Authors.
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Sogabe, Yusuke ; Nakamura, Haruna ; Nakagawa, Tomoyuki ; Hasegawa, Satoko ; Asano, Tomoya ; Ohta, Hiroyuki ; Yamaguchi, Kazuo ; Mueller, Martin J. ; Kodama, Hiroaki ; Nishiuchi, Takumi
概要:
It is known that wounding systemically activates the expression of various defense-related genes in plants. However, mos
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t studies of wound-induced systemic response are concerned with a leaf-toleaf response. We have recently reported that the long distance signaling was also observed in the shoots of Arabidopsis seedling with wounded roots. We identified early and late root-to-shoot responsive (RtS) genes that were upregulated in the shoots of root-wounded seedlings at 30 min and 6 h post-injury, respectively. It is likely that the primary signals were rapidly transfered from injured roots to shoots, and then these signals were converted into chemical signals. In fact, increase of JA and OPDA content activated the expression of early and late RtS genes in shoots, respectively. In addition, we visualized wound-induced root-to-shoot response by using RtS promoter- luciferase (Luc) transgenic plants. Analysis of the AtERF13 promoter::Luc transgenic plants clearly shows that the wound-induced root-to-shoot signaling was rapidly activated via the vascular systems. © 2011 Landes Bioscience.
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論文
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Nishiuchi, Takumi ; Masuda, Daisuke ; Nakashita, Hideo ; Ichimura, Kazuya ; Shinozaki, Kazuo ; Yoshida, Shigeo ; Kimura, Makoto ; Yamaguchi, Isamu ; Yamaguchi, Kazuo
概要:
金沢大学学際科学実験センター遺伝子研究施設<br />Phytopathogenic fungi such as Fusarium spp. synthesize trichothecene family phytotoxins. Alth
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ough the type B trichothecene, deoxynivalenol (DON), is thought to be a virulence factor allowing infection of plants by their trichothecene-producing Fusarium spp., little is known about effects of trichothecenes on the defense response in host plants. Therefore, in this article, we investigated these effects of various trichothecenes in Fusarium-susceptible Arabidopsis thaliana. Necrotic lesions were observed in Arabidopsis leaves infiltrated by 1 μM type A trichothecenes such as T-2 toxin. Trichothecene-induced lesions exhibited dead cells, callose deposition, generation of hydrogen peroxide, and accumulation of salicylic acids. Moreover, infiltration by trichothecenes caused rapid and prolonged activation of two mitogen-activated protein kinases and induced expression of both PR-1 and PDF1.2 genes. Thus, type A trichothecenes trigger the cell death by activation of an elicitor-like signaling pathway in Arabidopsis. Although DON did not have such an activity even at 10 μM, translational inhibition by DON was observed at concentrations above 5 μM. These results suggested that DON is capable of inhibiting translation in Arabidopsis cells without induction of the elicitor-like signaling pathway. © 2006 The American Phytopathological Society..
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