甘蓝型油菜低温发芽QTL定位及遗传分析

Cold stress is one of the typical abiotic stresses. The rapeseed germination is easily affected by low temperature as the delay of seeding times, resulting in decreased seed germination rate and delayed emerging time, ultimately affect crop growth. Breeding resistant cultivars by utilization of resistance genes is considered to be the most economical and effective method to ensure seed germination under low temperature stress. Our preliminary study indicated that Huyou21 showed a high level of resistant to low temperature stress. To study the genetic mechanisms, the mapping population from Huyou21 and sensitive material was used as materials for research. In this study, QTLs for low temperature germinability were identified by QTL-seq. Then, molecular markers for candidate region will be developed based on the QTL mapping results. The QTLs conferring the resistance to low temperature will be mapped combined with the results of genetic analysis and phenotype identification, and the closely linked molecular markers will be developed. Subsequently, the novel gene(s) of seed germination under low temperature stress will be predicted by analyzing the sequences of the candidate region. This project will rich the knowledge of inheritance rule of rapeseed germination under low temperature stress in theory, and also set up a foundation of the molecular marker assisted breeding, fine mapping and genes cloning in practice.

低温胁迫是一种典型的非生物胁迫，晚直播油菜在种子萌发期易遭受低温侵袭，导致种子发芽时间延长，发芽率降低，严重影响作物的后期生长。发掘油菜中的耐低温发芽基因，培育低温发芽耐性品种是保证低温胁迫下种子正常发芽最经济有效的途径。项目组前期研究发现，沪油21表现为耐低温发芽特性。为定位沪油21中的耐低温发芽基因，本研究拟以沪油21与低温发芽敏感材料杂交所配置的分离群体为研究对象，利用QTL-seq等技术明确耐低温发芽QTL所在染色体，然后基于初定位结果，开发候选区段分子标记，通过对分离群体进行遗传分析和低温发芽力鉴定，定位耐低温发芽基因，获得与该位点紧密连锁的分子标记，基于候选区段基因注释信息，预测耐低温发芽候选基因。该项目的实施将在理论上丰富对油菜耐低温发芽遗传规律的认识，也将在实践中为分子标记辅助育种、基因精细定位和克隆等奠定基础。

甘蓝型油菜是世界重要油料作物，易遭受低温侵袭。发掘油菜中的耐低温发芽基因，培育低温发芽耐性品种是保证低温胁迫下作物种子正常发芽最经济有效的途径。为探讨油菜低温发芽遗传机制，本项目利用耐低温发芽油菜种质（沪油21）与低温发芽敏感材料（3429）杂交所配置的包含574个F2株系的分离群体为研究对象，利用QTL-seq技术明确耐低温发芽QTL所在染色体，然后基于QTL-seq扫描结果，开发特异染色体分子标记，精细定位耐低温发芽基因。基于该作图群体，通过QTL-seq技术结合遗传连锁分析方法，在染色体A09和C01上分别检测到控制低温发芽的QTL，分别命名为qLTGA9-1和qLTGC1-1。qLTGA9-1位于SSR标记Nys9A212和Nys9A215之间，标记间物理距离为341.86 kb，共包含69个预测基因，其中6个预测基因的突变位点影响编码蛋白功能。qLTGC1-1位于SSR标记Nys1C96和Nys1C117之间，标记间物理距离为1.31 Mb，共包含133个预测基因，其中5个预测基因的突变位点影响编码蛋白功能。这些研究结果将为甘蓝型油菜低温耐性深入研究、候选基因克隆和分子标记辅助育种等奠定遗传基础。此外，选取36份低温耐性不同的甘蓝型油菜种质为研究材料，通过2年6期分期播种试验，从中筛选获得了3份耐低温宜迟播种质，为后续甘蓝型油菜耐低温宜迟播遗传研究和优势品种选育奠定了材料基础。