Molecular characterization of Oryza sativa WRKY6, which binds to W-box-like element 1 of the Oryza sativa pathogenesis-related (PR) 10a promoter and confers reduced susceptibility to pathogens
Molecular characterization of Oryza sativa WRKY6, which binds to W-box-like element 1 of the Oryza sativa pathogenesis-related (PR) 10a promoter and confers reduced susceptibility to pathogens
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DOI：
10.1111/nph.13516
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发表时间：
2015-11-01
期刊：
影响因子：
9.4
通讯作者：
Hwang, Duk-Ju
中科院分区：
文献类型：
--
作者：
Choi, Changhyun;Hwang, Seon-Hee;Hwang, Duk-Ju
WRKY蛋白是调节防御相关基因表达的转录因子。水杨酸(SA)诱导的水稻WRKY6(OsWRKY6)是水稻病程相关10a(OsPR10a)的正调控基因。在体外实验中证实了OsWRKY6与W-box样元件1(WLE1)之间的物理相互作用，WLE1能正向调节OsPR10a/Probenazo诱导蛋白1的表达。包括OsPR10a在内的几个致病相关(PR)基因被结构性地激活，并且表达(Ox)OsWRKY6的转基因水稻植株对病原菌的抗性增强。相比之下，在转OsWRKY6-RNAi基因系中PR基因的诱导受到抑制，表明OsWRKY6是防御反应的正调控因子。OsWRKY6-OX株系表现为叶部病变，OsWRKY6-OX株系水杨酸(SA)含量高于野生型(WT)植株，编码SA生物合成关键酶的水稻异落酸合成酶1(OsICS1)的转录水平高于野生型(WT)植株。OsWRKY6在体内直接与OsICS1启动子结合。这表明OsWRKY6可以直接调节OsICS1的表达，从而增加SA的浓度。OsWRKY6能自动调节自身的表达。OsWRKY6蛋白的降解可能受泛素化的调节。我们的结果表明，OsWRKY6通过激活OsICS1的表达和稳定OsWRKY6来积极地调节防御反应。
WRKY proteins are transcription factors (TFs) that regulate the expression of defense-related genes. The salicylic acid (SA)-inducible Oryza sativa WRKY6 (OsWRKY6) was identified as a positive regulator of Oryza sativa pathogenesis-related 10a (OsPR10a) by transient expression assays. A physical interaction between OsWRKY6 and W-box-like element 1 (WLE1), which positively regulates OsPR10a/probenazole induced protein 1 expression, was verified in vitro.Several pathogenesis-related (PR) genes were constitutively activated, including OsPR10a, and transgenic rice (Oryza sativa) plants overexpressing (ox) OsWRKY6 exhibited enhanced disease resistance to pathogens. By contrast, PR gene induction was compromised in transgenic OsWRKY6-RNAi lines, suggesting that OsWRKY6 is a positive regulator of defense responses. OsWRKY6-ox lines displayed leaf lesions, and increased OsWRKY6 levels caused cell death.Salicylic acid (SA) concentrations were higher in OsWRKY6-ox lines than in wild-type (WT) plants, and transcript levels of Oryza sativa isochorismate synthase 1 (OsICS1), which encodes a major enzyme involved in SA biosynthesis, were higher in OsWRKY6-ox lines than in WT. OsWRKY6 directly bound to the OsICS1 promoter in vivo. This indicates that OsWRKY6 can directly regulate OsICS1 expression and thereby increase SA concentrations. OsWRKY6 autoregulates its own expression. OsWRKY6 protein degradation is possibly regulated by ubiquitination.Our results suggest that OsWRKY6 positively regulates defense responses through activation of OsICS1 expression and OsWRKY6 stabilization.