水稻株型增变基因TR1的分子调控机制及其育种利用研究

Plant architecture is the morphological basis of yield formation. Plant architecture improvement, and molecular identification and utilization of its related genes will be helpful to design breeding. In this study, the semi dominant mutant with multi tillers dwarfing late heading phenotype tr1 (tree-like on chromosome 1) was obtained from mutant library of the Nipponbare after EMS mutagenesis. On the base of fine mapping and identifying candidate gene, we will carry out the cell morphology observation, isolation and cloning of the plant architecture gene; TR1 gene function analysis by constructing different function and expression vectors and Cas9 mutant analyzing; and RNA-seq and yeast two-hybrid system to screening, verifying and analyzing of upstream and downstream genes and interacting proteins of TR1 using tr1 allelic mutants. This research will preliminarily ascertain the genetic and molecular mechanism of the TR1 (OsMSH7) gene in plant architecture development,and its mutator phenotype mechanism, and creat rice mutants using OsMSH7 mutator phenotype method. It will enrich rice plant-architecture germplasm, and benefit our understanding of the gene regulatory networks, provide theoretical and materials basis of molecular design breeding for high yield with new plant-type in rice.

株型是产量建成的形态学基础，株型改良及相关基因的分子鉴定和利用将有利于设计育种。本申请以一个从日本晴的EMS诱变库中获得的多蘖矮秆迟抽穗的突变体tr1（tree-like on chromosome 1）为研究材料，在已精细定位并确定候选基因（植物特有的MSH7增变基因）的研究基础上，拟进一步利用TR1等位突变体、完成细胞形态观察，分离和验证该株型控制基因；同时构建不同的功能和表达载体及Cas9突变体，开展tr1的功能研究；结合RNA-seq和酵母双杂交分析，开展上下游基因和互作蛋白的筛选、验证和分析，初步探明TR1(OsMSH7)基因如何高转录表达形成增变表型及株型发育遗传和调控机理；以及利用OsMSH7具有增变表型创制水稻突变体；本研究为丰富水稻株型的基因资源和种质资源，开展分子设计育种，培育新株型高产水稻新品种打下了良好的理论和材料基础

株型是产量建成的形态学基础。我们利用EMS诱变的多蘖矮秆迟抽穗突变材料tr1，图位克隆了在第1染色体上的TR1增变基因，测序发现目标基因的外显子上发生了G-C单碱基突变，TR1基因编码植物特有的MSH7蛋白，参与DNA错配修复，调控水稻的重要农艺性状，增加水稻突变率。TR1突变表型与玉米的corngrass1类似，与miR156b/c基因互作错误表达所致，产生系列增变的植株表型。TR1（OsLF）基因定位于细胞膜，通过酵母筛库筛选到一个与粒型调控蛋白OsFWL1互作；进一步利用酵母双杂，双分子荧光互补技术，免疫共沉淀技术，证明了OsLF在细胞膜上和OsFWL1互作，负调控粒长；过表达OsLF后，突变体株高变矮，粒长变短，结实率下降，生育期延长。而敲除OsLF后，突变体只有粒型变长，其他表型未发生显著变化。揭示了水稻OsLF（TR1）-OsFWL1分子模块调控粒型机制，创制了长粒新种质；水稻TR1/MSH7-OsLHP1-miR156-H3k27me3分子模块调控株型分子机制，创制了系列多蘖矮化的新种质。为水稻株型改良及相关基因的设计育种提供了理论和材料基础。发表论文4篇，发明专利2个，培养博士后1名，研究生6名（其中，国际博士留学生2名）。