水稻SST基因在生长发育及盐胁迫适应中的作用机制研究

We found a rice salt tolerant mutant, which showed glabrous on leaves and hulls. Its fertility decline and growth period was delayed. The previous study showed that the salt tolerance was controlled by a single recessive gene. By gene fine mapping and sequencing analysis, a member of the SBP-box gene family was identified as the candidate gene. And it was confirmed that the candidate gene was just the salt tolerant gene by the genetic complementarity test. On this basis, quantitative RT-PCR, GUS fusion gene and GFP fusion gene experiments will be used to analyse the expression of the gene to explicit the temporal and spatial gene expression profile and the subcellular localization of the salt tolerant gene. Through transpiration analysis, ions and small molecules detection, signaling molecules and ROS metabolism related enzymes analysis of the wild type and mutant, we can find out which physiological pathway it relates to. Through the NGS analysis of transcriptome (include small RNA) of the wild type and mutant, related salt tolerant genes expression analysis, double mutant analysis between SST and related salt tolerant genes, at the same time through the degeneration of chromatin immunoprecipitation experiment. The direct downstream gene of the salt tolerant gene might be acquired and analysed, then the physiological and molecular regulation mechanism of the salt tolerant gene might be clarified preliminarily. The above research results will provide the theoretical basis for thoroughly elucidating the physiology mechanism and molecular regulation mechanism of salt tolerance in rice. Meanwhile the results will add new reference for a comprehensive understanding of SBP-box gene family protein functions in rice growth and development.

我们筛选到一个水稻耐盐突变体，同时表现为“光身”，而且育性下降、生育期延长。遗传分析表明为单基因隐性突变，精细定位和测序分析将一个SBP-box基因确定为候选基因，遗传互补试验证明该基因确为耐盐基因SST的目标基因。本项目拟在此基础上通过采用定量RT-PCR、GUS融合基因和GFP融合基因等方法进行基因表达分析，明确耐盐基因SST的时空表达模式和亚细胞定位；通过耐盐突变体的蒸腾作用分析、离子和小分子物质分析、信号分子及ROS代谢相关酶分析，分析SST基因影响的生理代谢路径；通过转录组（包括小RNA组）分析、突变体中相关耐盐基因表达分析、SST基因与相关耐盐基因的双突变体分析和染色质免疫共沉淀分析，明确SST蛋白的直接靶标基因并且初步阐明SST基因在水稻生长发育和盐胁迫适应中的作用机理。研究结果为水稻耐盐分子机制的阐明提供依据，也为深入研究SBP-box基因在水稻生长发育中的功能奠定基础。

申请者前期筛选到一个水稻耐盐、光身突变体，通过定位将一个SBP-box基因作为候选基因。.本课题通过敲除试验和过量表达证实水稻OsSPL10就是SST，该基因正向调控水稻叶片和种子上表皮毛发育，负向调控水稻耐盐性。OsSPL10主要在水稻幼穗和茎表达，其编码蛋白OsSPL10定位在细胞核中。OsSPL10调控OsWOX3B和OsPLT2的表达，且OsSPL10与OsWOX3B存在蛋白互作，OsSPL10可能通过OsWOX3B-OsPLT2途径调控水稻表皮毛发育。盐胁迫条件下OsSPL10对水稻钾钠离子含量有影响，推测OsSPL10可能通过调节钠钾离子来影响耐盐性。外源GA3和IAA可以影响水稻叶片近轴面表皮毛发育，其中OsSPL10可能通过GA途径调控水稻表皮毛发育。OsSPL10突变可以减弱MeJA对水稻幼苗生长的抑制作用，推测其可能通过MeJA途径影响水稻生长。.以上结果大概勾勒出OsSPL10在水稻耐盐和表皮毛发育方面功能的基本框架，为深入研究分子机理奠定了基础。