Plant Osmosensors

植物渗透传感器

• 批准号: 1457257
• 负责人: Zhen-Ming Pei
• 金额: $ 60万
• 依托单位: Duke University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-08-15 至 2019-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1457257&HistoricalAwards=false
• 关键词: Plant; Osmosensors

Water is crucial to all aspects of plant growth, development and ecological distribution, as well as agricultural production. Drought triggers osmotic-stress signaling events in plants, which regulate the gene expression network and subsequent physiological and developmental processes, reducing water loss. Among these signaling events, the initial perception for osmotic stress is poorly understood at the gene level. The project is designed to identify and study the genes encoding sensors for drought/water as well as their regulatory components in plants. In this project, the identification and examination of the gene family of water sensors will not only further our understanding of how plants sense water, but also provide potential genetic targets for engineering drought resistant plants, such as crops, grasses and trees.It is well established for over the last 20 years that osmotic stress evokes a transient increase in cytosolic Ca2+ concentration ([Ca2+]i), which is thought to be involved in osmosensing. However, the molecular nature of the corresponding osmosensing components remains largely unknown. Using aequorin Ca2+ imaging-based unbiased forward genetic screens, Arabidopsis mutants defective in osmotic stress-induced [Ca2+]i increases (oici) were previously isolated, and one gene, OSCA1, was identified as the founding member of a functionally novel and evolutionarily conserved family of channel proteins. OSCA1 forms hyperosmolality-gated, non-selective cation channels with Ca2+ permeability in the plasma membrane. Suppression of OSCA1 results in attenuated osmotic signaling in stomatal movements and root growth, suggesting that OSCA1 functions as an osmosensor in plants. In this project, the detailed biophysical properties of OSCA1 channels will be determined (Aim 1). Then, 14 other OSCA1 homologs will be screened for their osmosensing activities (Aim 2), and their physiological functions in drought stress and root hydrotropism will be assessed (Aim 3). Finally, novel osmosensing-related components will be isolated via fine-mapping of additional oici mutants (Aim 4). This project will establish the Ca2+-mediated sensory machinery by which plants perceive water availability in both external environments and internal tissues.

水对植物生长、发育、生态分布以及农业生产的各个方面都至关重要。干旱触发植物的渗透胁迫信号事件，调节基因表达网络和随后的生理发育过程，减少水分流失。在这些信号事件中，渗透胁迫的初始感知在基因水平上知之甚少。该项目旨在识别和研究植物中编码干旱/水传感器的基因及其调控成分。在本项目中，水传感器基因家族的鉴定和研究不仅将进一步加深我们对植物如何感知水的理解，而且还将为作物、草和树木等抗旱植物的工程设计提供潜在的基因靶点。在过去的20年里，渗透胁迫引起细胞质内Ca2+浓度（[Ca2+]i）的短暂增加，这被认为与渗透感应有关。然而，相应的渗透传感组分的分子性质在很大程度上仍然未知。利用基于aequorin Ca2+成像的无偏正向遗传筛选，先前分离出了渗透胁迫诱导[Ca2+]i增加（oici）缺陷的拟南芥突变体，其中一个基因OSCA1被确定为功能新颖且进化上保守的通道蛋白家族的创始成员。OSCA1在质膜上形成高渗透压门控的、非选择性的Ca2+渗透性阳离子通道。OSCA1的抑制导致气孔运动和根生长中的渗透信号减弱，表明OSCA1在植物中起渗透传感器的作用。在本项目中，将确定OSCA1通道的详细生物物理性质（目标1）。然后，将筛选14个其他OSCA1同源物的渗透活性（Aim 2），并评估其在干旱胁迫和根系亲水性中的生理功能（Aim 3）。最后，将通过对其他oici突变体的精细定位分离出新的渗透传感相关成分（Aim 4）。本项目将建立Ca2+介导的感觉机制，植物通过该机制感知外部环境和内部组织中的水分可用性。