基于高密度遗传图谱对水稻粒形QTL定位及分析

Mapping and analysis of QTLs for grain size in rice based on high density genetic map

通过对水稻粒形相关性状进行QTL定位和不同位点的聚合效应分析,为后续辅助育种、粒形相关基因的精细定位奠定基础。在3个不同的季节种植籼稻品种魔大穗与航恢315的192个重组自交系群体,根据全基因组重测序技术构建的高密度遗传图谱,利用完备区间作图法(inclusive composite interval mapping,ICIM)定位水稻粒形性状QTL,并用复合区间作图法(CIM)对结果进行验证。对粒长、粒宽、长宽比、千粒重、谷粒截面积、谷粒周长进行QTL定位, ICIM法和CIM法分别检测到65个和81个QTL,其中有40个QTL能同时被检测到,成簇分布于2号、3号、5号、7号、8号、9号染色体上。将其归类为6个QTL簇,其中Loci5、Loci7、Loci9能被重复定位到,且控制至少4个性状,表型贡献率最高分别为15.74%、54.07%、15.89%,这些位点是后续基因功能研究的候选位点。根据bin标记分型结果将不同子代在各个QTL区间分为航恢315型和魔大穗型,在重组自交系后代进行聚合效应分析。经处理及数据分析发现聚合增效等位基因数量越多的个体,其在不同环境对应的表型值也越高。鉴定到携带多个增效等位基因的株系,可作为育种实践中增效等位基因的供体亲本。

In this study,QTL mapping of grain size related traits and pyramided effect analysis of different sites were carried out to lay a foundation for marker-assisted breeding and fine mapping of grain size related genes.A total of 192 recombinant inbred lines derived from indica rice cultivars Modasui and Hanghui 315 were planted in three different seasons.A high-density genetic map was constructed based on whole-genome resequencing technology,and the QTLs for grain shape traits were mapped by complete interval mapping(ICIM)and verified by composite interval mapping(CIM).QTL mapping was carried out for grain length,grain width,length-width ratio,1000-grain weight,cross-sectional area,and grain circumference.50 and 81 QTLs were detected by ICIM and CIM,respectively,and 43 QTLs could be detected simultaneously.They were clustered on chromosome 2,3,5,7,8,and 9.Their highest phenotypic contribution rates were 15.74%,54.07%,and 15.89%,respectively.These loci could be the candidate loci for subsequent gene function studies.According to the genotyping of bin markers,different progenies were divided into Hanghui 315 type and Modasui type in each QTL interval.Further data processing and analysis were performed to analyze the pyramided effect of QTLs.It was found that individuals with more pyramided synergistic alleles showed higher phe notypic values in different environments.The identified lines with multiple synergistic alleles can be used as donor parents in breeding practices.