RUI: PIRL1 & PIRL9, novel plant Ras-group related LRR proteins essential for male gametophyte function

富亮氨酸重复蛋白(LRR)是一个广泛存在于不同物种中的大基因/蛋白超家族。这些蛋白质中的LRR结构域与其他蛋白质特异结合，许多LRR蛋白在细胞信号网络中发挥作用。植物细胞内RAS组相关的LRRs是一个新的植物LRRs家族，与动物和酵母中的一类LRRs的亲缘关系比以往所描述的植物蛋白更近。一些来自动物的相关LRR蛋白参与了癌症和发育过程中重要的细胞信号通路。本项目重点研究了模式植物拟南芥中两个密切相关的PIRL基因PIRL1和PIRL9。对基因敲除突变体的初步实验表明，这些基因在花粉发育中具有多余和必要的作用，而花粉发育是植物繁殖的关键过程。这项拟议的研究将结合遗传学、显微镜和分子策略，通过确定PIRL1和PIRL9基因在整个植物中的作用并确定它们参与的细胞途径和生化相互作用，来获得对PIRL1和PIRL9在植物繁殖中的功能的综合了解。具体目标：1)完成PIR1：PIRL双突变和突变花粉的遗传学研究；2)更准确地确定PIRL突变如何影响花粉发育；3)确定PIRL蛋白的亚细胞位置；以及4)通过鉴定PIRL结合蛋白来研究生化功能。另一个目标是通过提供后基因组植物生物学的本科生研究机会来培养未来的美国科学家：这项研究将在一所本科学院进行，该学院有很高比例的学生攻读研究生课程并从事生物学职业。通过提供对植物信号转导和花粉发育的遗传要求的见解，这项工作最终应该有助于有效地操纵植物生长，从而有利于农业生产力和植物育种。

Leucine-Rich Repeat proteins (LRRs) constitute a large gene/protein superfamily found in diverse species. LRR domains in these proteins bind specifically to other proteins, and many LRR proteins act in cell signaling networks. PIRLs (Plant Intracellular Ras-group-related LRRs) are a novel family of plant LRRs more closely related to a class of LRRs from animals and yeast than to previously described types of plant proteins. Some related LRR proteins from animals are involved in cell signaling pathways important in cancer and development.This project focuses on PIRL1 and PIRL9, two closely-related PIRL genes from the model plant Arabidopsis thaliana. Preliminary experiments with gene knockout mutants have shown that these genes have redundant and essential roles in pollen development, a process crucial for plant reproduction. The proposed research will employ a combination of genetic, microscopy, and molecular strategies to obtain an integrative understanding the functions of PIRL1 and PIRL9 in plant reproduction, by identifying where these genes act in the context of the whole plant and defining the cellular pathways and biochemical interactions in which they take part. Specific objectives: 1) complete genetic studies of pirl1:pirl9 double mutants and mutant pollen; 2) more precisely define how pirl mutations impact pollen development; 3) determine the sub-cellular locations of PIRL proteins; and 4) investigate biochemical functions by identifying PIRL-binding proteins. An additional objective is to train future U.S. scientists by providing undergraduate research opportunities in post-genomic plant biology: this research will be carried out at an undergraduate college with a high percentage of students who pursue graduate study and careers in biology. By providing insights into plant signal transduction and the genetic requirements for pollen development, this work should ultimately contribute to effective manipulation of plant growth, with benefits for agricultural productivity and plant breeding.