甘蓝型油菜QTL qSWA3-2 调控种子重量（大小）的分子机制研究

解析甘蓝型油菜粒重形成的分子机理，可以为油菜产量的遗传改良提供理论依据和基因资源。项目组前期利用DH群体检测到一个稳定遗传的千粒重QTL（qSWA3-2），并采用图位克隆策略，精细定位并克隆了其目标基因SWA3-2，该基因编码一个预测的细胞分裂素受体激酶。在此基础上，本项目拟通过基因敲除、增强表达和细胞学观察等手段揭示SWA3-2的生物学功能；采用启动子驱动GUS表达、原位杂交和亚细胞定位明确SWA3-2的基本分子特征，揭示SWA3-2等位基因转录后调控差异的机制；通过体外蛋白磷酸化实验，验证qSWA3-2基因编码蛋白的激酶活性，并通过体内和体外互作分析确认其底物；通过转录组分析筛选下游基因，并构建swa3-2与下游基因的双突变体予以遗传验证，从而初步鉴定SWA3-2调控油菜粒重的分子通路；利用SWA3-2的优良单倍型改良油菜骨干亲本。该研究将揭示SWA3-2调控油菜种子大小和粒重的分子机

Uncovering the genetic and molecular mechanism underlying seed weight/size variations in rapeseed (Brassica napus L.) promotes yield improvement not only with theoretical guidance but also excellent gene resources. Previous studies in our group identified a stable QTL, qSWA3-2, controlling seed size and weight in multiple environments. Through a map-based cloning strategy, qSWA3-2 was successfully cloned, which encodes a putative cytokinin receptor-like histidine kinase. In this project, we attempt to uncover the biological function of SWA3-2 by using transgenic lines with enhanced gene expression and with gene knockout, with the aid of morphological and cellular analysis. We will characterize SWA3-2 by promoter-GUS system, mRNA in situ hybridization and sub-cellular localization, and investigate the allelic difference in post-transcriptional regulation of SWA3-2 by RLM-RACE and RNA sequencing. The putative kinase activity of SWA3-2 and the predicted substrates of SWA3-2 will be clarified by biochemical assay in vitro and in vivo. Moreover, we will establish a primary regulatory pathway mediated by SWA3-2 through RNA-seq as well as double-mutant assay. The promising allele of SWA3-2 will be transferred into important parental lines to enhance their yield potential. These outcomes will enrich our understanding of molecular regulation of seed size/weight in rapeseed and provide elite alleles as well as functional markers for true breeding.