油菜耐湿主效QTL qWR9-2的精细定位与候选基因克隆

Waterlogging is one of the most serious factors limiting the rapeseed production, especially along the middle and lower reaches of the Yangtze which was the main producing area of Brassica napus in China. Therefore, study on the genetic control of the waterlogging tolerance has an important scientific significance and application value. Fine mapping of the major QTL for waterlogging tolerance is the first step to reveal candidate genes, however, to our knowledge, few QTL associated with waterlogging tolerance was fine mapping in B. napus. QTL qWR9-2 was the major QTL for waterlogging tolerance in our previous study, which was identified in a F2:3 population containing 188 lines. This QTL could be repeatedly detected in two experiments and explained 47.58% and 23.57% of the phenotypic variation, respectively. In this research, we will confirm the qWR9-2 based on bulked-segregant analysis (BSA) method combined with next-generation sequencing (NGS) technology. In addition, a BC4F2 population will be constructed and used for fine mapping qWR9-2 within 1.0 cM. Finally, gene expression analysis will be carried out through quantitative RT-PCR. The completion of this research can provide useful clues to extrapolate the molecular mechanism of waterlogging tolerance, and establish the foundation of marker assisted selection of breeding in rapeseed.

湿害是影响我国油菜生产的最大限制因素之一，尤其对长江中下游油菜主产区造成显著影响。研究油菜耐湿性的遗传机制和分子机理具有重要的科学意义和应用价值。精细定位耐湿主效QTL是揭示耐湿相关基因的首要步骤，但目前对油菜耐湿QTL进行精细定位的报道还很少。前期项目组利用包含188个株系的F2:3家系群体对油菜苗期耐湿性进行QTL定位，发现了控制耐湿性的主效QTL位点qWR9-2，两年分别解释表型变异的47.58%和23.57%。本项目拟以该群体为基础，利用全基因组测序的BSA方法，对该主效QTL位点做进一步的鉴定；同时构建用于qWR9-2精细定位的BC4F2群体，将qWR9-2精细定位于1.0 cM内；根据基因功能确定候选基因，并对候选基因进行表达分析。研究结果可为揭示油菜耐湿性的调控机制及通过分子设计方法培育耐湿性的油菜品种奠定基础。

湿害是影响我国油菜生产的最大限制因素之一，尤其对长江中下游油菜主产区造成显著影响。研究油菜耐湿性的遗传机制和分子机理具有重要的科学意义和应用价值。甘蓝型油菜耐湿性的强弱受基因型控制，遗传差异较大，并且缺少高耐湿种质资源。本项目基于已构建的高密度SNP遗传图谱，对包含189个家系的RIL群体的耐湿性进行QTL定位。在5个环境中共检测到17个与耐湿性相关的QTL，其中QTL cqWT.C3-2，cqWT.C8-1和cqWT.C8-2能在两个环境中重复检测到。QTL cqWT.C3-2在两个环境中分别解释表型变异的10.3%和23.3%，是本研究中检测到的耐湿性主效QTL位点。此外，基于油菜的60 K SNP芯片，通过对520个甘蓝型油菜品种/品系构成的自然群体进行耐湿性状的关联分析，在两个环境中共获得80个与油菜耐湿性状相关的SNP。将连锁与关联分析的结果进行比较分析，发现两种定位方法没有定位到共同的位点。本项目将连锁分析与关联分析及生物信息学等想结合，在研究方法上有一定的创新性，研究成果为油菜耐渍基因的图位克隆奠定了基础。本研究获得的耐渍性材料，为油菜耐渍新品种的选育提供了新的种质资源。