MYB转录因子SINGLE FLOWER调控番茄果实数目的分子机制

花序结构和花数目是决定作物产量的重要性状。作为重要茄果类蔬菜作物的番茄，单株花数与植株光合作用同化产物供给之间的平衡更是影响果实产量和品质的关键因素。因此，鉴定、克隆控制番茄花序结构和花序花数的基因，剖析基因调控的分子机制，是利用基因编辑等技术进行该性状的种质创新和定向改良的关键和基础。项目组通过EMS诱变获得了两个单花番茄突变体，基因克隆发现一个MYB转录因子SF的突变可能导致了该表型。通过酵母单杂和双杂文库筛选，鉴定到一个GATA和两个TCP类转录因子，推测它们一起调控番茄花序花数的形成。申请项目拟在此基础上，利用基因编辑技术创建SF调控网络中关键基因的突变体，并结合基因表达、转录调控和蛋白互作等技术方法解析MYB、GATA和TCP类转录因子协调调控番茄花序发育、控制花序花数的分子机制，为利用基因编辑等技术定向改良番茄等作物的花序性状提供理论依据和新靶点。

Inflorescence architecture and the number of flowers per plant are highly associated with crop yield. Fruit yield and quality of tomato, an important fleshy fruit crop, is drastically affected by the balance between the number of flowers per plant and the assimilate supply. To improve the traits by introducing new elite alleles using gene editing technology or through other molecular breeding techniques, it is very necessary to identify genes controlling inflorescence architecture and flower number and dissect the molecular mechanism underlying the regulation by these genes. We identified two tomato mutants producing 1 or 2 solitary flowers from our EMS mutant pools. Preliminary data shows that the mutant phenotype was caused by mutations in a MYB transcription factor. Screening for transcription factors regulating SF expression by yeast one hybrid identified a GATA transcription that binds to SF promoter. Two TCP transcription factors of tens candidates interacting with SF in vitro were also identified through screening a yeast library made from tomato shoot apical meristems. With the information we gained from our experiments, we in this proposal want to create CRISPR-CAS9 mutants for some key factors including the GATA and TCP transcription factors that are putative involved in SF-mediated regulation of flower formation, and then apply various approaches, including analysis of gene expression (qRT-PCR, in situ hybridization, RNA-seq), transcription regulation (EMSA, Yeast one hybrid, ChIP-seq) and protein interactions (Yeast two hybrid, Co-IP and Pulldown), to reveal the molecular mechanism underlying the coordinated regulation of inflorescence development and flower formation by MYB, GATA and TCP transcription factors. We expect the outcome of this project will further our understanding on the transcriptional regulation of inflorescence architecture and flower number in tomato. In addition, the information gained in this project may also provide strategies and tools for tomato breeders to create new lines of improved inflorescence architectures.