Molecular genetic analysis of LORELEI function in inducing the arrest of pollen tube growth in the Arabidopsis female gametophyte

我们赖以生存的种子是双重受精的产物。植物繁殖的这一基本过程需要通过花粉管将精子细胞输送到卵子和胚囊的中央细胞(雌配子体)。尽管双受精早在一个多世纪前就被发现了，但控制双受精的分子机制和基因仍然知之甚少。我们发现拟南芥Lorelei(LRE)基因在早期繁殖过程中具有重要作用。在lre突变体中，花粉管在释放精子之前不会停止雌配子体的生长，因此无法完成双受精。我们发现LRE编码一种膜锚定的糖基磷脂酰肌醇(GPI)锚定蛋白，因此是介导花粉管和雌配子体之间信号转导的一个很好的候选者。在本项目中，将通过分子、遗传和细胞生物学实验来阐明Lorelei蛋白在诱导拟南芥雌配子体花粉管生长停滞中的作用。具体地说，我们将确定Lorelei蛋白在助细胞中的亚细胞定位，以及Lorelei GPI锚定是否对其在助细胞中的功能至关重要。此外，还将研究Lorelei在诱导花粉管生长停止中的作用机制，并将确定其他与Lorelei一起在这一重要信号事件中发挥作用的基因。对种子形成的全面分子理解可能有助于开发操纵植物繁殖和提高种子产量的工具。因此，该项目可能产生重大影响，因为种子是主食、纤维、营养、工业产品和生物燃料的来源。此外，该项目还将对人力资源产生重大影响。本科生将进行一些实验，两名博士后研究员和一名研究技术员将接受实验程序、数据分析和科学数据呈现方面的培训。

The seeds we depend on for our food are products of double fertilization. This essential process in plant reproduction requires delivery of sperm cells by the pollen tube to the egg and central cells of the embryo sac (female gametophyte). Although double fertilization was discovered more than a century ago, the controlling molecular mechanisms and genes remain poorly understood. We identified the Arabidopsis LORELEI (LRE) gene as critically important for an early step in reproduction. In lre mutants, pollen tubes do not arrest growth in the female gametophyte prior to releasing the sperm cells and consequently fail to complete double fertilization. We found that LRE encodes a putative membrane-anchored glycosylphosphatidylinositol (GPI)-anchored protein and is, therefore, an excellent candidate for mediating some aspects of signaling between the pollen tube and the female gametophyte. In this current project, molecular, genetic, and cell biological experiments will be conducted to elucidate the role of LORELEI protein in inducing pollen tube growth arrest in Arabidopsis female gametophytes. Specifically, we will determine the subcellular localization of LORELEI protein in the synergid cell and whether the LORELEI GPI anchor in is essential for its function in the synergid cell. The mechanism of LORELEI function in inducing the arrest of pollen tube growth will also be examined, and additional genes that function with LORELEI in this important signaling event will be identified.A comprehensive molecular understanding of seed formation may help generate tools to manipulate plant reproduction and increase seed yield. Consequently, this project could have a major impact since seeds are a source of staple food, fiber, nutrition, industrial products and biofuels. Additionally, this project will also have a major human resource impact. Undergraduate students will carry out some experiments and two post doctoral fellows and a research technician will be trained in experimental procedures, data analysis, and scientific data presentation.