The role of WIH1/2 peptides in the transition from somatic to sporogenic fate in plants

该项目的目标是研究调节植物生殖系起始的分子机制。与在胚胎发生早期将生殖系与索马分开的动物不同，植物已经进化出在成体阶段从体细胞产生单倍体配子的迷人能力;这一特性反映了植物细胞显著的发育可塑性，并且对于种子生产和植物繁殖具有经济重要性。在花的雌性器官中，每个胚珠的单个体细胞被重编程为大孢子母细胞（MMC），随后进入减数分裂，最终产生卵细胞。调节MMC建立的分子途径在很大程度上是未知的。在第一个资助期间，我们发现了植物特异性WIH 1（WINDHOSE 1）和WIH 2肽启动MMC发展的新分子机制。我们的数据表明，在一个模型中，WIH肽在胚珠的表皮作为新的系绳分子RABA 1装饰的囊泡，提供生长素转运蛋白PINFORMED 1的质膜。植物激素生长素在表皮中的随后积累对于下面的MMC的发育是必不可少的。在第二个资助期，我们的目标是测试这个模型，并剖析WIH功能的MMC调节的分子原理。这些研究将增强我们对重编程细胞命运和启动生殖途径的基本发育过程的理解，同时有助于经济上重要的植物物种的生殖策略的概念。

The goal of this project is to investigate the molecular mechanisms that regulate germline initiation in plants. Unlike animals where the germline is set apart from the soma early in embryogenesis, plants have evolved the fascinating ability to generate haploid gametes from somatic cells at the adult stage; a property that reflects the remarkable developmental plasticity of plant cells and that is of economic importance for seed production and plant propagation. In the female organs of the flower, a single somatic cell of each ovule becomes reprogrammed into a megaspore mother cell (MMC), which subsequently enters meiosis from which ultimately the egg cell is derived. The molecular pathways regulating the establishment of the MMC are largely unknown. During the first funding period, we discovered a novel molecular mechanism for the plant specific WIH1 (WINDHOSE1) and WIH2 peptides in initiating MMC development. Our data suggest a model where WIH peptides in the epidermis of the ovule act as novel tether molecules for RABA1-decorated vesicles that deliver the auxin transport protein PINFORMED1 to the plasma membrane. Subsequent accumulation of the phytohormone auxin in the epidermis is essential for the development of the underlying MMC. In the second funding period, we aim at testing this model and dissect the molecular principles of MMC regulation by WIH function. These studies will enhance our understanding of fundamental developmental processes that reprogram cell fate and initiate generative pathways, and at the same time contribute to concepts of reproductive strategies in economically important plant species.