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. Issue 3 (17th June 2015)

• Record Type: Journal Article
• Authors: Choi, Changhyun; Hwang, Seon‐Hee; Fang, Il Ran; Kwon, Soon Il; Park, Sang Ryeol; Ahn, Ilpyung; Kim, Jung Bong; Hwang, Duk‐Ju
• Is Part Of: New phytologist. Volume 208:Issue 3(2015:Dec. 01)
• Page Start: 846
• Page End: 859
• Publication Date: 2015-06-17
• Subjects: Botany -- Periodicals; 580
• DOI: 10.1111/nph.13516
• Languages: English
• ISSNs: 0028-646X

Abstract

<abstract abstract-type="main" id="nph13516-abs-0001"> <title>Summary</title> <p> <list id="nph13516-list-0001" list-type="bullet"> <list-item> <p>WRKY proteins are transcription factors (TFs) that regulate the expression of defense‐related genes. The salicylic acid (SA)‐inducible <italic>Oryza sativa</italic> WRKY6 (OsWRKY6) was identified as a positive regulator of <italic>Oryza sativa pathogenesis‐related 10a</italic> (<italic>OsPR10a</italic>) by transient expression assays. A physical interaction between OsWRKY6 and W‐box‐like element 1 (WLE1), which positively regulates <italic>OsPR10a/probenazole induced protein 1</italic> expression, was verified <italic>in vitro</italic>.</p> </list-item> <list-item> <p>Several pathogenesis‐related (<italic>PR</italic>) genes were constitutively activated, including <italic>OsPR10a</italic>, and transgenic rice (<italic>Oryza sativa</italic>) plants overexpressing (ox) <italic>OsWRKY6</italic> exhibited enhanced disease resistance to pathogens. By contrast, <italic>PR</italic> gene induction was compromised in transgenic <italic>OsWRKY6</italic>‐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.</p> </list-item> <list-item> <p>Salicylic acid (SA) concentrations were higher in <italic>OsWRKY6</italic>‐ox lines than in wild‐type (WT) plants, and transcript levels of <italic>Oryza sativa isochorismate synthase 1</italic> (<italic>OsICS1</italic>), which encodes a major enzyme involved in SA biosynthesis, were higher in <italic>OsWRKY6</italic>‐ox lines than in WT. OsWRKY6 directly bound to the <italic>OsICS1</italic> promoter <italic>in vivo</italic>. This indicates that OsWRKY6 can directly regulate <italic>OsICS1</italic> expression and thereby increase SA concentrations. OsWRKY6 autoregulates its own expression. OsWRKY6 protein degradation is possibly regulated by ubiquitination.</p> </list-item> <list-item> <p>Our results suggest that OsWRKY6 positively regulates defense responses through activation of <italic>OsICS1</italic> expression and OsWRKY6 stabilization.</p> </list-item> </list> </p> </abstract>