Zhang Fan, Zeng Dan, Huang Liyu, Shi Yingyao, Chen Tengjun, Zhang Fan, Zhou Yongli
Institute of Crop Sciences/National Key Facility for Crop Gene Resources and Genetic Improvement, Chinese Academy of Agricultural Sciences, 12 South Zhong-Guan-Cun Street, Beijing, 100081, China.
Graduate School of Chinese Academy of Agricultural Sciences, 12 South Zhong-Guan-Cun Street, Beijing, 100081, China.
Rice (N Y). 2019 Nov 11;12(1):80. doi: 10.1186/s12284-019-0338-2.
Salt stress and bacterial blight caused by Xanthomonas oryzae pv. oryzae (Xoo) are key limiting factors of rice (Oryza sativa L.) yields. Members of sucrose non-fermenting 1 (SNF1)-related protein kinase 2 (SnRK2), which is a family of plant-specific Ser/Thr kinases, are important components of signaling pathways involved in plant developmental processes and responses to stresses. There are 10 members of the SnRK2 family in rice; however, their functions are poorly understood, as are the underlying molecular mechanisms.
In this study, we found that OsSAPK9, which belongs to the SnRK2 family, positively regulated salt-stress tolerance and strain-specific resistance to bacterial blight in rice. RNA sequencing revealed that there were 404 and 1324 genes differentially expressed in OsSAPK9-RNAi in comparison with wild-type plants under salt-stress conditions and after Xoo inoculation, respectively, which participate in basic metabolic processes. In total, 65 common differentially expressed genes involved mainly in defense responses were detected both under salt-stress conditions and after Xoo inoculation. Moreover, in vivo and in vitro experiments demonstrated that OsSAPK9 forms a protein complex with the molecular chaperones OsSGT1 and OsHsp90, and transgenic plants overexpressing OsSGT1 exhibited decreased tolerances to salt stress and significantly increased resistance levels to bacterial blight. Thus, OsSAPK9 may function as a center node regulator of salt-stress responses and disease-resistance pathways through its interaction with OsSGT1 in rice.
This study confirms that OsSAPK9 functions as a positive regulator of salt-stress responses and disease resistance through its interaction with OsSGT1 in rice.
盐胁迫和由水稻白叶枯病菌（Xanthomonas oryzae pv. oryzae，Xoo）引起的白叶枯病是水稻（Oryza sativa L.）产量的关键限制因素。蔗糖非发酵1（SNF1）相关蛋白激酶2（SnRK2）家族属于植物特有的丝氨酸/苏氨酸激酶家族，是参与植物发育过程和应激反应信号通路的重要组成部分。水稻中SnRK2家族有10个成员；然而，它们的功能以及潜在的分子机制尚不清楚。
在本研究中，我们发现属于SnRK2家族的OsSAPK9正向调控水稻对盐胁迫的耐受性和对白叶枯病的菌株特异性抗性。RNA测序显示，与野生型植株相比，在盐胁迫条件下和接种Xoo后，OsSAPK9-RNAi中分别有404个和1324个基因差异表达，这些基因参与基本代谢过程。总共检测到65个主要参与防御反应的共同差异表达基因，在盐胁迫条件下和接种Xoo后均有表达。此外，体内和体外实验表明，OsSAPK9与分子伴侣OsSGT1和OsHsp90形成蛋白复合物，过表达OsSGT1的转基因植株对盐胁迫的耐受性降低，对白叶枯病的抗性水平显著提高。因此，OsSAPK9可能通过与水稻中的OsSGT1相互作用，作为盐胁迫反应和抗病途径的中心节点调节因子发挥作用。
本研究证实，OsSAPK9通过与水稻中的OsSGT1相互作用，作为盐胁迫反应和抗病性的正向调节因子发挥作用。
