甘蓝型油菜黄籽性状形成的遗传网络解析

Yellow seeds of rapeseed have valuable characteristics, including high oil and protein contents as well as low fiber, lignin, and pigment contents in seed cake, making yellow seed character as one of the main objectives in rapeseed breeding. However, no yellow-seed germplasm exists in natural Brassica napus. In this study, previously created yellow-seeded near-isogenic line W82 (47.6% of oil content) and black-seeded parent (41.6% of oil content) will be used as research materials. We aim to analyze transcriptome and proteome differences at three key stages of seed development by performing RNA sequencing and iTRAQ analysis, respectively. Quantitative analysis and variation in accumulated seed components (procyanidin, flavonoid, polyphenol, lignin, fiber, oil, and protein content) in yellow and black rapeseed will be performed to determine the main genes or transcription factors related to the formation of the yellow seed character. We also aim to determine the effects on biosynthesis and distribution of oil and protein in rapeseed, identify differentially expressed genes, and prove the functionality of these candidate genes. Furthermore, these candidate genes will be functionally proved and contribute to the dissection of genetic networks of yellow seed character. This project has important theoretical significance on studies involving the molecular mechanism of yellow seed formation in B. napus. Thus, results of this study will possibly promote the development and use of this new germplasm.

黄籽油菜的种子由于具有较高的含油量，其饼粕具有蛋白质含量高、纤维素、木质素含量低和色素少等优点，黄籽性状正成为油菜品质育种的重要目标之一。甘蓝型油菜没有天然的黄籽种质资源。本项目选用细胞工程方法创建的甘蓝型油菜黄籽新种质—近等基因系W82（含油量47.6%）和黑籽亲本（含油量41.6%）作为实验材料，选择种子成熟过程中3个关键时期，运用转录组和蛋白质组（iTRAQ）相结合的方法开展基因组的比较研究，结合黄/黑籽种子成分（原花青素、类黄酮、多酚、木质素、纤维素、含油量和蛋白质等）的定量分析和变化规律的研究，与之相同时期差异表达基因进行关联分析，寻找与油菜黄籽性状形成以及影响油脂和蛋白质物质合成和分配的关键基因或转录因子，并进行功能验证，同时解析黄籽性状形成的遗传网络。本项目不仅对甘蓝型油菜黄籽性状形成的分子机理的研究具有重要的理论意义，而且对尽快开发和利用该种质也具有重要的推动作用。

黄籽甘蓝型油菜具有高含油量，饼粕蛋白质含量高、纤维素和色素少等优点，因而成为油菜品质育种的重要目标之一。甘蓝型油菜没有天然的黄籽种质资源。本研究以细胞工程方法创建的甘蓝型油菜黄籽新种质—近等基因系W82和黑籽亲本为实验材料，比较了黄、褐籽材料种子不同发育时期油脂成分、多酚物质、饼粕营养成分的含量差异，为系统了解黄、褐籽材料的品质差异奠定了基础；通过sRNA-seq、RNA-seq、甲基化测序、蛋白质组（iTRAQ）分析，比较了黄、褐籽材料不同时期种子的转录水平、DNA水平和蛋白水平的差异，筛选获得可能与甘蓝型油菜色素调控相关的差异表达miRNA和mRNA等；通过差异表达miRNA（miR172）及其靶基因的功能分析，我们发现miR172可能正调控花青素的积累，其靶基因编码蛋白BnTOE2可能通过与MYB61、DFR等互作负调控花青素的积累，且上述表型变化与BnTT3、BnTT5、BnTT6、BnTT8、BnTT18的表达变化有关；通过差异表达基因的功能验证，我们发现BnTT2的纯合敲除株系出现黄籽表型，BnTT2可通过与BnTT8、TTG1、TTG2、BnCPC等互作影响油菜花青素的合成与积累。本研究通过不同组学分析了解了与油菜黄籽性状形成相关的关键基因或转录因子，并通过候选差异表达miRNA和差异表达基因的功能验证，初步表明BnTT2、miR172及靶基因BnTOE2可能参与甘蓝型油菜色素合成和积累的分子调控过程，为丰富油菜黄籽性状形成的遗传网络奠定了基础。