Genetic Analysis of Osmotic Stress Signal Transduction in Plants

干旱和盐碱引起的渗透胁迫是植物进化的主要选择力，也是限制作物生产力的重要因素。了解植物检测和响应渗透胁迫的机制对基础植物生物学和作物改良具有重要意义。以往的研究表明，植物对渗透胁迫的适应是由一个复杂的调控通路网络控制的，但这些通路中的大多数关键成分仍未被确定。该项目继续了先前使用拟南芥突变体识别此类调控成分的工作。利用表达RD29A- luc（受胁迫诱导的RD29A启动子控制的萤火虫荧光素酶）基因的植物，通过荧光素酶成像，从遗传筛选中恢复了几个渗透胁迫响应基因表达受损的拟南芥突变体。一些突变通过图谱克隆被分离出来，这为了解植物的渗透胁迫反应提供了重要的新见解。例如，克隆SAD1揭示了RNA代谢参与渗透胁迫信号传导。本研究基于这些发现，旨在识别渗透胁迫信号转导的新调控成分。具体目标包括克隆和鉴定两个涉及渗透胁迫信号的新基因位点，以及鉴定现有突变体（如sad1）的遗传抑制因子。

Osmotic stress caused by drought and salinity has been a major selective force in plant evolution and an important factor limiting crop productivity. Understanding the mechanisms by which plants detect and respond to osmotic stress is important for basic plant biology and for crop improvement. Previous studies suggested that plant adaptation to osmotic stress is governed by a complex network of regulatory pathways, but most of the key components in these pathways remain to be identified. This project continues previous effort in using Arabidopsis mutants to identify such regulatory components. Several Arabidopsis mutants impaired in osmotic stress-responsive gene expression were recovered from a genetic screen by luciferase imaging using plants that express the RD29A-LUC (firefly luciferase under control of the stress-inducible RD29A promoter) transgene. Some of the mutations have been isolated through map-based cloning, which provided significant new insights into osmotic stress responses in plants. For example, cloning of SAD1 revealed the involvement of RNA metabolism in osmotic stress signaling. This research is based on such findings and is aimed at identifying new regulatory components in osmotic stress signal transduction. Specific aims include the cloning and characterization of two new genetic loci involved in osmotic stress signaling, and the identification of genetic suppressors of existing mutants such as sad1.