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控植物生殖系启动的分子机制。与动物不同的是，在胚胎发生的早期，种系与体细胞是分开的，植物已经进化出了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，对种子生产和植物繁殖具有重要的经济意义。在花的雌性器官中，每个胚珠的单个体细胞重新编程为大孢子母细胞(MMC)，然后进入减数分裂，最终形成卵细胞。调控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，我们发现了植物特异性WIH1(WINDHOSE1)和WIH2多肽启动MMC发育的新的分子机制。我们的数据表明了一种模型，在该模型中，胚珠表皮中的WIH多肽作为RABA1装饰的小泡的新的系链分子，将生长素运输蛋白PINFORMED1运送到质膜。随后植物激素生长素在表皮中的积累对于潜在的MMC的发展是必不可少的。在第二个资助期，我们旨在验证这一模型，并剖析WIH功能对MMC调控的分子机制。这些研究将加深我们对基本发育过程的理解，这些过程重新编程细胞命运并启动生殖途径，同时有助于在经济上重要的植物物种中提出繁殖策略的概念。

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.