2个与单产相关的水稻短根突变体的基因克隆与功能研究

Accumulating evidence indicated the positive correlation between grain yield of rice with root length. However, the underling molecular mechanism is still unclear. Our group identified two yield-related short root mutants, Osksr2 and Osksr8, respectively from a series of short root mutants in rice. Besides the short root phenotype, the mutants also displayed decreased pollen viability, seed setting rate and grain yield per plant, which provided good models to study the correlation between root length and grain yield. The two genes have been cloned by map-based cloning already. The project will focus on the functional characterization of these two genes using molecular and cell biology methods. Microarray and protein-protein interaction analysis will be conducted to study their roles in the regulation of root elongation and pollen viability. We aims to clarify the molecular mechanisms of root elongation and positive correlation between root length and grain yield, and provide genetic materials and theoretical support to breeding of root system.

越来越多的研究表明水稻的根长与单产呈正相关，但二者之间的分子机理还不清楚。本课题组从系列的短根突变体中鉴定获得2个与单产相关的短根突变体Osksr2和Osksr8，除了短根表型外，还表现花粉育性、结实率和单株产量下降等性状，是研究根长与单产相关性的很好模型。目前，通过基因定位已图位克隆到这2个基因。本研究将通过分子生物学与细胞生物学方法研究这2个基因的功能，同时围绕这2个基因参与根系伸长和花粉育性的调控体系，利用芯片分析系统、蛋白互作分析等实验，阐明根系伸长的分子机制及根系长度与单产之间呈正相关的分子机理，并为根系育种提供可能的基因材料和理论指导。

水稻根系决定了地上部许多性状的形成，越来越多的研究表明水稻根长是所有根系性状中最重要性状，水稻根长与单产呈正相关。课题组研究了与有效分蘖数、花粉育性、结实率和单株产量等农艺性状相关的短根突变体OskasI和Ospelo，并图位克隆到了这2个基因。.突变体OskasI的主根、侧根和不定根的根长受到明显的抑制，株高、有效分蘖数、千粒重、结实率和花粉活力等明显比野生型差。组织切片等实验发现短根是根尖分生区细胞分裂和伸长区细胞的伸长异常所致，在主根的分生区和侧根积累了大量的活性氧。OsKASI基因在根、茎、叶、花和种子上均有表达，除花外其他表达都较强，呈组成型表达，OsKASI蛋白定位在质体上。OsKASI基因编码β-酮脂酰-ACP合酶，参与了脂肪酸的合成调控途径，影响脂肪酸的去饱和途径，同时也影响了甾醇的含量，说明脂肪酸合成在水稻的根系生长发育和农艺性状形成中起着重要的作用。.突变体Ospelo的主根、不定根和侧根的生长受到抑制，组织切片等实验发现短根是根尖分生区细胞分裂能力差所致，株高、有效分蘖数、结实率都低于野生型，花器官和花粉呈败育状。OsPELO基因在根茎叶等组织均有表达，呈组成型表达，OsPELO蛋白定位在线粒体上。OsPELO基编码一个pelota蛋白，RNA-seq分析发现该基因参与调控一系列生物过程，如各种胞内代谢过程和胚胎与胚后发育过程、木质素合成和茉莉酸合成、次级代谢物合成通路和植物抗病响应等。.本项目在Planta、Frontiers in Plant Science、西北植物学报等刊物发表论文6篇，投稿1篇（“PelotaRegulates Root Development and Defense Responses in Rice” submittd to Annals of Botany）；授权国家发明专利2项，申请发明专利2项。