Molecular Mechanisms of CO2 Signal Transduction

CO2信号转导的分子机制

• 批准号: 0417118
• 负责人: Julian Schroeder
• 金额: $ 66万
• 依托单位: University of California-San Diego
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-10-15 至 2010-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0417118&HistoricalAwards=false
• 关键词: Molecular; Mechanisms; CO2; Signal; Transduction

Stomatal pores are formed by guard cell pairs in the epidermis of leaves. Stomata regulate the diffusion of CO2 into leaves for photosynthetic carbon fixation and control transpirational water loss of plants. A network of signal transduction mechanisms in guard cells sense and transduce CO2, water status, light and other environmental stimuli to regulate stomatal apertures for optimization of CO2 influx, water loss and plant growth under diverse conditions. Elevated CO2 concentrations in leaves cause stomatal closure, whereas reduced CO2 concentrations result in stomatal opening. Photosynthesis and respiration cause CO2 concentration changes in leaves. Moreover, atmospheric [CO2] is predicted to double within the present century and these ambient CO2 increases reduce stomatal apertures of different plant species by up to 40 %. However, relatively little is known about the molecular signal transduction mechanisms in guard cells that mediate CO2-induced stomatal movements. A study suggests that cytosolic calcium ([Ca2+]cyt) elevations contribute to CO2-induced stomatal movements. New findings in the P.I.'s laboratory show that changes in [CO2] modulate cytosolic [Ca2+]cyt elevations in Arabidopsis guard cells. The guard cell CO2 response provides an opportune system to analyze hypotheses that cytosolic Ca2+ patterns contribute to signal transduction in plants. The long term goal of this research is to achieve an understanding of the molecular mechanisms that mediate CO2 signal transduction in guard cells. The research will investigate the hypothesis that CO2 modulation of the [Ca2+]cyt elevation pattern in guard cells contributes to CO2-induced signal transduction during stomatal closing and/or opening. To test this hypothesis, studies with the following specific aims will be pursued: Characterize CO2 responses of wildtype guard cells. Examine the effects on CO2 signal transduction of known mutants that affect Ca2+ and/or abscisic acid signaling at distinct points within the guard cell signaling network, to characterize genetic mechanisms that affect CO2 signaling and to determine which components are specific to defined signaling pathways. Gain insight into how [Ca2+]cyt is transduced and specifically define the roles of selected guard cell-expressed CDPKs in stomatal responses. Characterize new CO2 signaling mutants. The P.I. will further pursue outreach efforts through public forums and through research and career training and preparation of undergraduate and high school students. Understanding the molecular mechanisms by which CO2 modulates stomatal apertures is fundamental to understanding the regulation of gas exchange between plants and the atmosphere, will help to predict effects of atmospheric CO2 elevation on stomata and may also contribute to future engineering of crop plants and plant carbon sinks in the face of changing environmental conditions.

气孔由叶表皮的保卫细胞对形成。气孔调节CO2向叶片的扩散，实现光合固碳和控制植物蒸腾失水。保卫细胞中的信号转导机制网络感知和吸收CO2、水分状况、光和其他环境刺激，以调节气孔开度，从而优化CO2流入、水分损失和植物生长。叶片中CO2浓度升高导致气孔关闭，而CO2浓度降低导致气孔开放。光合作用和呼吸作用引起叶片CO2浓度的变化。此外，大气[CO2]预计将在本世纪内翻一番，这些环境CO2的增加减少了不同植物物种的气孔开度高达40%。然而，相对知之甚少的分子信号转导机制介导的保卫细胞CO2诱导的气孔运动。一项研究表明，胞质钙（[Ca 2 +]cyt）的升高有助于CO2诱导的气孔运动。P.I.的新发现的实验室表明，[CO2]的变化调节拟南芥保卫细胞胞质[Ca 2 +]cyt的升高。保卫细胞CO2响应提供了一个合适的系统来分析假设，胞质Ca 2+模式有助于在植物中的信号转导。 本研究的长期目标是了解保卫细胞中介导CO2信号转导的分子机制。该研究将探讨以下假设：保卫细胞中[Ca 2 +]cyt升高模式的CO2调节有助于气孔关闭和/或打开期间CO2诱导的信号传导。为了检验这一假设，将进行具有以下特定目标的研究：表征野生型保卫细胞的CO2反应。研究已知突变体对保卫细胞信号网络中不同点的Ca 2+和/或脱落酸信号传导的影响，以表征影响CO2信号传导的遗传机制，并确定哪些组分对特定的信号传导途径具有特异性。深入了解[Ca 2 +]cyt是如何转导的，并具体定义选定的保卫细胞表达的CDPKs在气孔反应中的作用。表征新的CO2信号突变体。私家侦探将通过公共论坛以及通过研究和职业培训以及为本科生和高中生做准备，进一步开展外联工作。 了解CO2调节气孔开度的分子机制是理解植物与大气之间气体交换调节的基础，将有助于预测大气CO2升高对气孔的影响，也可能有助于未来面对不断变化的环境条件的作物和植物碳汇工程。