大白菜是以叶球为主要食用器官的重要蔬菜作物，但其叶球发育的分子调控机理尚不明确。本项目以申请者实验室创建的具有相同遗传背景的大白菜平塌（叶片平塌、散叶型）突变体fg1及其野生型为材料，在已确定该突变性状由一对隐性基因控制，并初步定位了突变位点的基础上，进一步通过分离群体极端性状单株测序验证突变基因位点，确定其序列变异特点；利用RNA-seq解析大白菜结球相关基因的表达调控网络和时空变化规律；同时分析叶球发育、内源激素和叶片解剖结构的表型差异，初步明确大白菜结球的信号调控途径；结合CRISPR基因编辑和真空渗透转化体系，开展结球关键基因的功能验证等研究。该研究不仅对叶球发育调控基因进行鉴定，而且对新发现关键基因的功能及调控结球的信号途径解析研究，揭示关键基因对大白菜结球的调控机理。项目的开展有助于推进大白菜叶球发育的分子机制的深入研究，也可为大白菜结球性状分子标记辅助选择育种提供技术基础。

Chinese cabbage (Brassica rapa L.ssp. pekinensis) is an important vegetable crop and its leafy head is the main edible organ. However, the molecular mechanism of leafy head development is unclear. Based on one ethylmethane sulfonate (EMS)-induced flat growth mutant (flat and divergent leaf type) with the same genetic background as Chinese cabbage ‘A03’, the heredity analysis showed the mutant character was controlled by a pair of recessive gene and high-throughput sequencing (MutMap) preliminarily mapped mutant loci. The single plant in segregation population with extreme traits will be sequenced to confirm the mutant gene locus and sequence features which were detected in MutMap. RNA-seq will be used to identify the regulatory network of differentially expressed genes and spatio-temporal patterns of those genes in heading biological process of Chinese cabbage. The leafy head morphology, plant hormones and leaf anatomical structure will be analyzed to explore the signaling pathway during leaves heading. The function of the key gene will be confirmed via the CRISPR gene-editing technique together with vernalization-infiltration methods. This study will not only identify regulatory genes of leafy head, but also clarify the function of the new key gene and the signaling pathway of leaves heading, which will reveal the regulation mechanism of the leafy head formation. This project will facilitate the in-depth research of the molecular mechanism responsible for leafy head development and provide a technological base for molecular marker assisted breeding of the heading trait in Chinese cabbage.