OsDSR2在水稻响应干旱和盐胁迫中的调控机制

Currently, molecular mechanisms of stress resistance are one of the functional genomics’s research hotspots in rice. Although the molecular mechanisms of stress-inducible genes have been extensively characterized in a number of plant species, little is known regarding the regulatory mechanisms of stress-repressive genes. DUF966 family is uncharacterized gene family. The available data of public microarray databases show that DUF966 family genes are repressed by different abiotic stresses,which is deduced that these genes may be a kind of stress-repressive genes. In our previous study, OsDSR2 was significantly repressed by drought and salt stresses, overexpression of OsDSR2 could increase drought and salt stress sensitivities in rice, which suggested that OsDSR2 negatively regulated drought and salt stress tolerances of rice. Based on these results, the function of OsDSR2 and its promoter will be dissected employing genetically modified technology, OsDSR2 involved in ABA signaling pathway will be studied using genetics and molecular biology, OsDSR2-target genes will be selected and isolated by RNA-seq and real time PCR methods, and the interacting protein of OsDSR2 will be screened and verified by yeast two hybrid, pull down and BiFC assays. Taken together,the reseach will confirm the interacting relationship of OsDSR2 and ABA in regulating the stress tolerances of rice, and then it will completely uncover the regulatory mechanism of OsDSR2 in rice response to drought and salt stresses.

水稻抗逆分子机制是当前水稻功能基因组学研究的热点之一，虽然对胁迫诱导表达基因的调控机制进行了广泛研究，但对胁迫抑制表达基因的调控机理知之甚少。DUF966家族是一类未知功能的基因家族，芯片数据分析显示该家族基因受非生物胁迫的抑制表达，可能为一类胁迫抑制表达基因。我们前期的研究结果表明，该家族基因OsDSR2受干旱和高盐的抑制表达，OsDSR2的超表达转基因植株增加水稻对干旱和高盐的敏感性，暗示OsDSR2可能负调控水稻的抗旱耐盐性。本项目拟在此基础上，进一步利用转基因技术、RNA-seq、定量PCR、酵母双杂、pull down以及BiFC技术，解析OsDSR2基因及其启动子的功能，探究该基因参与的ABA信号途径，寻找并鉴定受OsDSR2调控的靶基因以及与OsDSR2互作的靶蛋白，确定OsDSR2及ABA在调控水稻抗逆性中的作用关系，以彻底阐明OsDSR2调控水稻抗旱耐盐性的具体分子机制。

DUF966基因家族是一类未知功能的基因家族，它们在水稻非生物胁迫应答中起着重要作用。前期研究表明，OsDSR2基因的超量表达增加了转基因水稻植株对盐胁迫和干旱胁迫的敏感性，同时降低了对ABA胁迫的敏感性。为了进一步研究OsDSR2调控水稻抗旱耐盐性的具体分子机制，本项目主要开展了OsDSR2 基因及其启动子在水稻应答干旱和盐胁迫中的作用、OsDSR2 是否参与ABA 信号途径、OsDSR2参与调控的下游相关基因的差异表达变化，以及寻找并鉴定与OsDSR2 相互作用的靶蛋白等方面的研究，结果表明OsDSR2 基因启动子在-643~-346 bp区域之间存在着与非生物胁迫相关的正调控元件，而在-346~1bp区域之间存在着与非生物胁迫相关的负调控元件；OsDSR2的抑制表达主要通过提高转基因植株中SOD和POD活性，增加脯氨酸的积累，从而使转基因水稻增强了抗旱耐盐性；OsDSR2主要通过ABA信号通路参与调控OsLEA3、RAB21、OsbZIP16等逆境相关基因的表达来提高苗期水稻的抗旱耐盐性；OsDSR2蛋白主要通过与Hsp70辅助分子伴侣蛋白sacsin（Os04g0675300）相互作用，与分子伴侣蛋白dnaJ GFA2（Os12g0168400）、过氧化氢酶（Os06g0727200 ）和控制水稻株型与产量相关蛋白PAY1（Os08g0407200 ）弱互作来协同调控水稻的干旱和盐胁迫的耐受性。本项目研究基本揭示了OsDSR2参与调控水稻抗旱耐盐性的分子机制，可为抗逆水稻遗传改良和分子育种提供基因资源和新材料。