水稻FMD1和FMD2基因调控雌配子体发育的分子机制

Angiosperm plant megaspore mother cell to mature female gametophyte is a key event in reproductive development, and the accuracy and order of development leads to the complexity of gene regulation. However, the related research is very scarce. Our previous study displayed that rice two gene mutations (fmd1 and fmd2 mutants) led to the defect of megaspore mother cell and female gametophyte, finally to seed abortion. Therefore, based on the basis of our preliminary studies and innovative ideas, to an important grain crop rice mutants, transgenic lines, and overexpression lines as materials, to take a variety of research methods, we will focus on the biological function, gene molecular regulation mechanism, and the upstream and downstream regulatory network of both FMD1 and FMD2 transcription factors during the megaspore mother cell and the female gametophyte development. It will reveal which cell types the megaspore mother cell origins from, how sporophytic cells influence the megaspore mother cell, and whether there is position effect and the developmental fate choices in female cell division and differentiation. We are trying to study the regulatory mechanisms of FMD1 and FMD2 genes in megaspore mother cell and female gametophyte development，and to seek the new female gametophyte specific expression gene. The study that will reveal the mechanism of both FMD1 and FMD2 transcription factors and look for new hybrid rice germplasm resources has extremely important significance. We will publish high level SCI papers 3-5 articles, and train a number of graduate students.

被子植物大孢子母细胞发生到雌配子体成熟是生殖发育的关键事件，其发育的精确性和有序性导致基因调控的复杂性。但是，国际上相关研究十分匮乏。我们前期研究发现水稻两个基因突变体fmd1和fmd2分别引起大孢子母细胞和雌配子体不能形成，导致种子败育。因此，本人基于前期研究基础，以粮食作物水稻突变体、转基因株系、过表达株系为材料，采取多种研究手段，重点研究大孢子母细胞发生和雌配子体发育中FMD1和FMD2两个转录因子的生物学功能、基因的分子调控机理、上下游调控网络；寻找雌配子体特异表达的基因；解析大孢子母细胞的细胞来源、阐明周围孢子体细胞的影响、揭示雌配子体细胞分裂和分化等位置效应和发育命运的抉择；探讨FMD1和FMD2基因在雌配子体发育中的分子调控机制。该研究成果对于揭示FMD1和FMD2的作用机理、寻找杂交水稻新的种质资源具有极其重要的意义。发表高水平SCI研究论文3-5篇，培养研究生若干名。

水稻是重要的粮食作物之一，水稻种子是人类赖以生存的食物来源，因此水稻种子的育性研究对于水稻作物育种至关重要。其中，水稻的雌性器官发育和受精生物学的研究是该领域研究的重点和难点。本项目研究主要从雌性器官（大孢子母细胞）的起始和双受精的开端为着眼点，重点研究了FMD1和FMD2两个重要基因的生物学功能和分子调控机制。（1）克隆了FMD1基因并分析了它的进化关系，发现FMD1基因主要在早期幼穗中优势表达；该基因的突变体fmd1表现出分蘖少，穗分枝少，小穗少，缺乏柱头和雌配子体败育；发现FMD1蛋白激活结构域为244-270和271-314两段；FMD1通过直接调控PID基因和间接控制LAX1基因调节水稻的雌性器官、分蘖和穗分枝。该基因研究增强人们对水稻分蘖和花穗发育机制的新认识，为“水稻分子设计育种”奠定理论基础，这对于揭示水稻雌配子体发育的分子调控机制和调控网络具有重要意义。（2）研究发现FMD2s蛋白是一种分泌小肽；其基因的突变体fmd2s引起雌配子体中卵细胞和中央细胞发生双受精障碍，最后导致种子败育；研究发现FMD2s基因在卵细胞中强烈表达，但在精细胞中不表达；发现上游转录因子YLs蛋白复合体可能调控下游FMD2s的表达而发挥重要的作用。这一研究发现FMD2A/B/C突变导致水稻双受精出现障碍，揭示了该基因调节水稻双受精的生物学过程和上游调控因子，为人们揭示重要的农作物水稻双受精的分子调控机制奠定了理论基础。（3）该研究还筛选了多个雌配子体特异表达的marker基因，以利于对雌配子体的发生与发育机制进行深入的研究；还构建了40多个雌配子体优势表达基因的CRISPR敲除载体，并获得大量转基因植株，正在进一步研究和解析这些基因在雌配子体发育中的生物学功能和分子调控机制；这为水稻育种提供了重要的遗传材料，具有至关重要的生物学意义。