油菜抗裂角近等基因系的构建以及新抗裂角主效位点BnSRI.A2的克隆

The mechanization of rapeseed production has been cumbered by the pod shatter of rapeseed varieties in China. Genetic analysis of pod shatter resistance is an important approach to accelerate varieties improvement on pod shatter resistance in rapeseed. However, there is very few pod shatter resistance genes used in rapeseed improvement. The knowledge about the gene effects, resistance mechanisms and utilization in breeding is still low. Based on the previous work on the identification of rapeseed lines with distinct resistance on pod shatter, we develop efficient marker-assisted selection (MAS) system for pod shatter resistance genes. Using MAS based conditional backcross breeding, we can introgress three major pod shatter resistance genes into R2, an elite rapeseed, to develop a serials of R2 near isogenic lines (NILs) harboring these genes. Furthermore, a new pod shatter resistance gene BnSRI.A2, was identified and fine mapped to a 200Kb region in rapeseed chromosome A2. Based on this work, we can further clone BnSRI.A2 and analyze the function and resistance mechanism of this candidate gene. Eventually, gene transformation technology will be used to confirm the function of candidate genes. The new development of this work will provide more valuable genes for pod shatter resistance improvement in rapeseed breeding, and a feasible strategy in the mechanical harvest in rapeseed.

加强油菜抗裂角遗传基础研究,是加快油菜抗裂角遗传改良进程，推动油菜机械化生产的重要举措。油菜裂角性状存在遗传变异，利用油菜抗裂基因培育抗裂角品种是目前提高收获指数最有效和经济策略之一。目前育种家对抗裂角抗性资源利用很少，对抗裂角基因效应和抗性机制了解还不多。本项目利用油菜自然群体进行抗裂角指数全基因组关联分析，定位发现了三个抗裂角位点，通过构建已定位的油菜抗裂角抗性基因的分子标记辅助选择体系，结合常规回交育种将三个抗裂角基因分别导入到优异亲本R2中，构建这些基因在R2遗传背景的近等基因系。同时通过图位克隆法克隆本课题发现的1个抗裂角新基因BnSRI.A2，评价其基因效应、解析基因的功能和抗性机制，研究结果为油菜抗裂角育种提供更多的基因资源，为油菜抗裂角品种改良提供理论依据。

加强油菜抗裂角遗传基础研究,是加快油菜抗裂角遗传改良进程，推动油菜机械化生产的重要举措。为了克隆油菜抗裂角主效基因，本研究在通过关联分析定位了6个抗裂角QTL。进一步发展遗传初级和次级群体对A9连锁群上两个多年多点三个群体中都能重复检测到的主效QTL位点qSRI.A9.1 和qSRI.A9.2进行精细定位和基因克隆。根据油菜参考基因组的注释信息，在qSRI.A9.1位点对应的候选区间内发现一个拟南芥SHP1的同源基因，命名为BnSHP1.A9。实验证明该基因协同调控角果离区邻近细胞的木质化，从而促进角果开裂种子散落。而该基因的遗传变异主要是因为启动子区间的LTR反转座子插入甲基化增强，导致该基因的功能丧失，而且在不同资源材料中都能检测到。另外我们发展近等基因系将qSRI.A9.2区间缩小到180Kb区间内，初步鉴定获得两个候选基因，功能验证是正在进行中。