板栗高雌突变体雌花分化的内源激素和分子调控机制

Chinese chestnut (Castanea mollisima Blume) commonly known as the "iron set crops", is an important ecological and woody grain plant species. Lack of effective measures to improve the number of female flowers is a key reason for poor production of this plant. To extend our works on flowers buds differentiation observation, the changes in endogenous hormone and carbohydrate contents, enzymatic activity, the preliminary work on chestnut flower buds transcriptome, and previous works on full-genome sequencing and analysis, we will use the buds of high female ratio mutants and ordinary Chinese chestnuts as the objective for the study in the project, combines the technique of immunogold electron microscopy with HPLC-MS and RNA sequencing to analyze the temporal and spatial patterns of the endogenous hormone and transcription spectrum difference during the critical differentiation period of the mixed buds. The genes involved in regulation of female and staminate flower were screened. The functions of these genes were analyzed by transient expression and transgenic Arabidopsis thaliana. This project aimed to have a preliminary understanding of molecular regulation mechanisms in male and female inflorescence differentiation. The expression and function analysis of the key genes which can promote the female flowers differentiation or can inhibition of the male flowers differentiation, could also provide gene resources and a theoretical basis for molecular breeding of Chinese chestnut’s high female flowers, which is also important to the study of the molecular mechanism of unisexual pistillate flower development.

板栗俗称“铁杆庄稼”，是重要的生态树种和木本粮食植物。生产中缺少有效的措施真正提高雌花量，是其产量难以有较大突破的关键。在我们开展板栗花芽分化进程，内源激素、酶和碳水化合物变化规律，花芽分化相关基因克隆和板栗雌雄花转录组初步研究，及前人板栗全基因组测序完成的基础上，本项目以冬季休眠前后高雌突变和普通板栗混合花芽为试材，结合免疫胶体金电镜技术、HPLC-MS技术及RNA sequencing技术，分析两者向雌花序原基分化过程中的内源激素组织分布规律和转录谱差异，筛选参与调控雌花分化和性别比例的基因。并通过瞬时表达及转基因拟南芥对其中重要的基因进行功能解析。项目实施旨在阐明调控板栗雌花分化的内源激素调控机理及基因调控网络，通过对关键基因进行表达和功能解析，亦可为板栗高雌品种的分子育种提供基因资源和理论依据，对果树单性雌花发育的分子机理研究亦有着非常重要的科学意义。

板栗俗称“铁杆庄稼”，是重要的生态树种和木本粮食植物。生产中缺少有效的措施真正提高雌花量，是其产量难以有较大突破的关键。本项目以冬季休眠前后板栗完全混合花芽和不完全混合花芽为试材，分析了板栗花芽中向雌花序原基分化过程中的内源激素组织分布规律和转录谱差异，并通过转录组合代谢组联合分析，研究调控板栗雌花分化的营养成分、内源激素调控机理及可能的基因调控网络，筛选参与调控雌花分化和性别比例的基因。.本研究按计划构建了临界期前、后板栗两种混合花芽的四个转录组和代谢组，获得了大量的差异基因和差异代谢产物。这些差异基因注释到分子功能，细胞组分和生物过程等不同的GO-term；主要集中于代谢通路，次生代谢产物生物合成、植物-病原菌互作等。差异代谢物主要富集在次生代谢物生物合成、氨基酸生物合成等途径。通过转录组及代谢组进行联合分析，我们得到了34个差异代谢物和686个差异基因，这些是决定完全混合花芽经过冬季休眠后向雌花序发育的重要物质和基因。并且构建了代谢物和基因相关性网络，获得了一个在雌花分化过程中重要的基因GRF2。同时，项目对6大类植物激素进行定性定量分析，结果表明异戊烯腺嘌啉、反式玉米素、茉莉酸甲酯、赤霉素19在混合花芽向雌花分化过程中起促进作用，水杨酸、顺式玉米素则有利于雄花的分化。ABA的积累有利于板栗花芽进入休眠，而较低含量的ABA有利于雌花序的分化。由于进一步研究需要，本项目资助还额外完成了板栗花芽发育相关的三个关键基因CmCHS、CmDFR、CmIFR的基因克隆、基因表达和生物功能初步验证工作。此外，在本项目研究结果的基础上，集成了一套通过生物调节剂结合栽培管理调控板栗雌花比例而达到增产丰产的绿色高效栽培技术，在大别山板栗产区进行推广应用，效果显著。通过项目的实施为板栗高雌品种的分子育种提供基因资源和理论依据，对果树单性雌花发育的分子机理研究亦有着非常重要的科学意义。