Ueno Yoshihisa, Matsushita Akane, Inoue Haruhiko, Yoshida Riichiro, Jiang Chang-Jie, Takatsuji Hiroshi
a Disease Resistant Crops Research Unit , National Institute of Agrobiological Sciences , Tsukuba , Ibaraki , Japan.
b Department of Agriculture , Ryukoku University , Yokatani 1-5, Seta Ohe-cho, Otsu-shi , Shiga , Japan.
Plant Signal Behav. 2017 Aug 3;12(8):e1356968. doi: 10.1080/15592324.2017.1356968. Epub 2017 Jul 31.
WRKY45 is a central regulator of disease resistance mediated by salicylic acid signaling in rice and its activation involves phosphorylation by OsMPK6. OsMPK6 phosphorylates WRKY45 at Thr266, Ser294, and Ser299 in vitro. Phosphorylation of Ser294 and/or Ser299 is required for full activation of WRKY45, but the importance of Thr266 phosphorylation has remained unknown. Here, we report on the characterization of Thr266 phosphorylation of WRKY45 in rice. Transient expression of mutant WRKY45 revealed that Thr266 is phosphorylated in vivo, together with Ser294/299. Replacement of Thr266 by Asn did not affect the enhanced Magnaporthe oryzae resistance afforded by WRKY45 overexpression. By contrast, replacement by Asp negated the enhancement of M. oryzae resistance. These results suggest that Thr266 phosphorylation acts negatively on WRKY45-dependent disease resistance.
WRKY45是水稻中水杨酸信号介导的抗病性的核心调节因子，其激活涉及OsMPK6的磷酸化作用。OsMPK6在体外使WRKY45的苏氨酸266、丝氨酸294和丝氨酸299发生磷酸化。丝氨酸294和/或丝氨酸299的磷酸化是WRKY45完全激活所必需的，但苏氨酸266磷酸化的重要性尚不清楚。在此，我们报道了水稻中WRKY45苏氨酸266磷酸化的特征。突变型WRKY45的瞬时表达表明，苏氨酸266在体内与丝氨酸294/299一起被磷酸化。用天冬酰胺取代苏氨酸266并不影响WRKY45过表达所带来的对稻瘟病菌抗性的增强。相比之下，用天冬氨酸取代则消除了对稻瘟病菌抗性的增强。这些结果表明，苏氨酸266磷酸化对WRKY45依赖的抗病性起负向作用。
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