甘蓝型油菜株型主效QTL(mqA1.13)的克隆和功能分析

Plant architecture directly affects the adaptability to cultivation, potential yield of crops and the suitability to modernized agricultural production, such as mechanical harvesting. Currently, unveiling the molecular bases of rapeseed plant architecture and breeding new varieties with ideal plant type are the focus of rapeseed genetics and breeding. Compared to cultivated varieties, Brassica napus 4942C-5 is a dwarf and compact line with contrasting plant architecture. A major QTL, mqA1.13, which simultaneously controls plant height and the average length of primary branches, was mapped in a primary screening for QTLs associated with rapeseed plant architecture. Near-isogenic lines (NILs) were established and mqA1.13 was restricted to a 432Kb region on A1 chromosome. In this study, the candidate gene of mqA1.13 will be cloned and functional analyzed through re-sequencing, RNA-Seq, hormone treatment and concentration assessment, cytological observation, transgenic techniques. Then the temporal and spatial expression patterns and the protein subcellular localization of the target gene will be investigated. The results will provide a strong foundation for unveiling the mechanisms underlying rapeseed plant architecture and help in breeding new rapeseed varieties suitable for mechanization.

株型影响作物的适应性、产量潜力以及是否适合现代化农业生产技术，如机械化收获等。揭示油菜株型建成的分子机理，培育具理想株型的油菜新品种是当前油菜遗传育种工作的重点内容。甘蓝型油菜4942C-5是一个株型截然不同于普通栽培种的矮秆紧凑型材料，前期株型相关QTL初步定位中，我们鉴定到一个同时影响株高和平均分枝长度的主效QTL位点：mqA1.13，构建了该位点的近等基因系，并将其锁定在A1染色体上一个432Kb的区段内。在此基础上，本研究拟借助于近等基因系大群体，通过重测序、RNA-Seq、激素试验、细胞学观察、转基因等技术手段，进一步缩小定位区间，克隆mqA1.13位点的基因，验证其功能；对目标基因进行时空表达特征及亚细胞定位研究，明确它参与的代谢调控网络，解析其参与株型调控的分子机制，为选育适合机械化生产的油菜新品种提供理论依据。

揭示油菜株型建成的分子机理，培育理想株型油菜新品种是当前油菜遗传育种工作的重点内容。甘蓝型油菜4942C-5是一个株型截然不同于普通栽培种的矮秆紧凑型材料。为克隆其主效QTL位点，我们通过激素试验、细胞学观察、重测序、RNA-Seq、sRNA和降解组测序和转基因等技术手段，找到了一些与株型相关的候选基因，个别基因已经进行了功能验证，主要结果如下：（1）激素实验结果表明，4942C-5矮杆紧凑型株型的形成与赤霉素和生长素等激素合成有关；（2）细胞学实验结果表明，矮秆紧凑株型茎顶端分生组织细胞中线粒体异常，可能与开花后顶端致死表型有关；（3）结合QTL定位信息以及BSA-Seq、RNA-seq、SRNA和降解组测序结果，筛选出了12个与激素有关的基因以及6个miRNA及其靶基因作为候选基因，正在进行转基因功能验证。转基因实验结果表明，其中2个miRNA（miR319和novel-miR1040）及其靶基因过表达会影响油菜顶端分生组织发育，从而影响株高和分枝习性；（4）通过亲本重测序开发了新的InDel标记，利用分子标记辅助选育技术，选育出3个株型改良的亲本系，配制了2个杂交种，目前正在进行观察试验。研究结果表明，油菜株型建成是由激素和miRNAs等重要因子参与的复杂调控网络综合作用的结果。研究结果将为揭示油菜株型建成的分子机理提供新的信息，为选育适合机械化生产的油菜新品种提供新的种质资源。