RNase Ⅲ结构域蛋白在低温下调控叶绿体发育并提高水稻耐低温能力的研究

Temperature is an important environmental factor. Rice is a thermophilic plant. Accidental low temperature can inhibit the growth of rice, affect the quality and yield. Therefore, improving the cold tolerance of rice has the vital significance..Previously, we cloned a rice gene controlling chloroplast development under low temperature. This gene is encoding a RNaseⅢ domain protein structure, and participate in the splicing of chloroplast genes under low temperature. Natural variations of the copies of this gene are existed in rice.The distribution of the different copies strongly related with the geographical distribution and indica/japonica differentiation. rice varieties distributed in north generally has two copies, those distributed in south usually has only one copy. Indica varieties generally have only a copy, and japonica varieties generally have two copies. A major QTL for seedling chlorophyll content under low temperature has been mapped in the chromosomal region of japonica unique copy. These results implied that the gene regulating the chloroplast development under low temperature may contribute to the low temperature resistance in rice. The project will study the physiological and biochemical function and the regulation pattern of this gene, elucidate the mechanism of increasing the low temperature resistance ability in rice, and explore the utility of this gene in rice varieties improvement, expanding the scope of the rice geography adapt to, and stable production, etc.

温度是植物生长的一个重要环境因素,水稻是喜温植物，偶然的低温能抑制水稻生长、影响品质甚至造成减产。因此，提高水稻耐低温能力有十分重要的意义。.我们在前期研究中克隆了一个调控水稻低温下叶绿体发育的功能基因，该基因编码RNaseⅢ结构域蛋白；初步发现该基因参与低温叶绿体基因的内含子剪切；该基因的拷贝在水稻中存在自然变异，不同拷贝的分布与水稻品种的地理分布和籼粳分化显著相关，高纬度的水稻品种一般有两个拷贝，而低纬度的品种一般只有一个拷贝，多数籼稻品系只有一个拷贝，而粳稻品系一般有两个拷贝；在籼粳交RIL群体中，一个耐低温能力相关的主效QTL被定位到粳稻特有拷贝的染色体区域，提示了该调控低温下叶绿体发育的基因与水稻耐低温能力相关。在此基础上，本项目拟系统研究该基因的调控模式和生理生化功能，阐明其提高水稻耐低温能力的作用机制，探索其在改良水稻品种，扩大水稻地理适应范围，以及稳产增产等方面的应用价值。

从LTA1-5/LTA1-11 X lta1-5/lta1-11的杂交后代中，利用分子标记辅助选择和SNP芯片鉴定，构建了LTA1-5和LTA1-11两个基因位点的4个近等基因系，通过分析了近等基因系在低温下的叶色表型和叶绿素含量，发现LTA1-5和LTA1-11这两个基因的功能既具有冗余性，也具有叠加性；分别构建了LTA1-5和LTA1-11的启动子GUS转基因载体，利用转基因植株分析了LTA1-5和LTA1-11的时空表达模式，发现LTA1-5基因和LTA1-11基因的启动子在不同组织中都有活性，其活性强弱没有明显差异；构建了LTA1-5/LTA1-11蛋白信号肽与绿色荧光蛋白GFP融合的瞬时表达载体，在水稻原生质体中瞬时表达，发现该该信号肽将GFP蛋白定位到叶绿体中，表明LTA1-5和LTA1-11是叶绿体蛋白；鉴定了近等基因系在高温和低温下18个叶绿体基因的内含子剪切效率，发现LTA1能促进叶绿体基因atpF的剪接，揭示了LTA1的分子功能。本项目共发表论文5篇，其中SCI 文章3 篇；获得专利1项；培养培养博士后2名、博士3名，硕士2名，在国际会议作学术报告1次。