基于bin水平的全基因组关联分析解析水稻8亲本高世代互交群体分蘖角的遗传基础

Multi-parent advanced generation inter-cross population (MAGIC) integrates the advantages of populations for linkage analysis and populations for genome-wide association mapping. Therefore it is recommended that QTL mapping with a MAGIC population possesses a powerful QTL detection with a high mapping resolution. However, up to date, QTL mapping for MAGIC population is mainly conducted with SNP-level genome-wide association study, which does not fully express the advantages of MAGIC population in QTL mapping. In this project, we will dissect the genetic basis of tiller angle for an 8-parent advanced generation inter-cross population of 560 F7 lines. We will measure tiller angle for the population at heading stage, sequence the 8 founders with a 20-fold genome coverage and sequence the MAGIC lines with a 5-fold coverage each. All SNPs among 8 founders will be identified and parent-of-origin bins for each line will be defined based on identical by state (IBS) and identical by decent (IBD). The bin map will be developed and the residual heterozygous bins of each MAGIC line will be recorded. Based on a mixed model, we will establish a genome-wide association mapping method at bin-level to map QTLs for tiller angle. The effects of parental alleles or bins at major QTLs will be evaluated and favorable alleles will be identified for breeders. According to the position of a previously detected major QTL, qTA8, the line with the heterozygous-targeted bin will be screened. And qTA8 will be cloned using the progeny of the line. Implementation of this project will enhance the power of QTL mapping of MAGIC population, and provide gene resources and theory instruct for plant architecture improvement in rice.

多亲本高世代互交群体（MAGIC）兼有关联分析群体和连锁分析群体的优点，因此，它在QTL定位能力和精度方面更有优势。但是，当前此类群体的QTL定位还是基于SNP水平的全基因组关联分析，没有充分发挥这类群体的优势。我们将利用包含560个F7家系的8亲本MAGIC群体，测定开花期的分蘖角度；对每个亲本和群体进行基因组深度测序，鉴定亲本间所有SNP，根据序列状态同一和后代同一信息，确定每个bin的亲本来源，建立群体的bin图，明确所有系的残余杂合bin。建立基于混合模型的bin水平的全基因组关联分析方法，揭示水稻分蘖角的遗传基础，评价主效QTL不同亲本等位基因效应，鉴定出优良等位基因。利用目标bin为杂合的MAGIC系自交后代，图位克隆前期定位的主效QTL qTA8。本项目的实施将创建提高MAGIC群体基因定位能力的方法，解析水稻分蘖角的遗传基础，为水稻株型育种提供基因资源和理论指导。