CO2 Signal Transduction in Plants

气孔是叶片表面的气孔，它1)调节二氧化碳从大气中扩散到叶片中进行光合碳固定，2)控制植物的蒸腾水分损失。保卫细胞感知二氧化碳浓度、水分状况、光线和其他环境刺激，并整合这些因素来调节气孔开度，以优化不同条件下二氧化碳进入植物、水分损失和植物生长。例如，叶片中二氧化碳浓度的升高会导致气孔关闭，而二氧化碳浓度的降低会导致气孔打开。据预测，大气中二氧化碳的浓度在本世纪内将翻一番：众所周知，二氧化碳水平的增加会使各种植物的气孔减少高达40%。这将对全球植物与大气之间的气体交换以及植物水分的利用效率产生深远的影响。然而，人们对二氧化碳诱导气孔运动的分子信号转导机制知之甚少。利用模式植物拟南芥，PI已经表明，编码碳酸酐酶基因的敲除突变体显示出二氧化碳诱导的气孔运动反应受损。这些蛋白质在气体交换调节的早期二氧化碳控制中发挥作用的假设将被调查。在这个项目中，这些蛋白质调节气孔对二氧化碳浓度的反应的遗传、分子、细胞和生理机制将被描述。广泛的影响：P.I.将通过公共论坛、通过研究和职业培训以及为高中生和本科生做准备来进行推广努力。代表人数不足的少数族裔学生将接受培训，以从事有监督的独立研究项目。此外，P.I.正在培训和培养博士后和研究生科学家，为他们在研究、技术和科学教育领域的高级独立职业做准备。了解二氧化碳调节气孔导度的分子机制是了解植物与大气之间气体交换调控的基础，将有助于预测大气二氧化碳升高对植物的影响，也可能有助于未来在面对大气二氧化碳持续上升和气候变化时提高作物水分利用效率或避免植物叶片热胁迫和植物碳汇。

Stomata are the pores on the surface of leaves that 1) regulate the diffusion of carbon dioxide from the atmosphere into leaves for photosynthetic carbon fixation and 2) control the transpirational water loss of plants. Guard cells sense carbon dioxide concentration, water status, light and other environmental stimuli and integrate these to regulate stomatal apertures for optimization of carbon dioxide influx into plants, water loss and plant growth under diverse conditions. For example, elevated carbon dioxide concentrations in leaves cause stomatal closure, whereas reduced carbon dioxide concentrations result in stomatal opening. The concentration of atmospheric carbon dioxide is predicted to double within the present century: carbon dioxide at these increased levels is known to reduce the stomatal apertures of various plant species by up to 40%. This will have profound effects on global gas exchange between plants and the atmosphere and the efficiency of plant water use. However, relatively little is known about the molecular signal transduction mechanisms that mediate carbon dioxide-induced stomatal movements. Using the model plant Arabidopsis, the PI has shown that knock-out mutants in genes encoding carbonic anhydrase show an impaired carbon dioxide-induced stomatal movement response. The hypothesis that these proteins function in early carbon dioxide control of gas exchange regulation will be investigated. In this project, the genetic, molecular, cellular and physiological mechanisms by which these proteins mediate the stomatal response to carbon dioxide concentrations will be characterized.Broader Impacts: The P.I. will pursue outreach efforts through public forums and through research and career training and preparation of high school students and undergraduate students. Underrepresented minority students will be trained to pursue supervised independent research projects. In addition the P.I. is training and preparing post doctoral and graduate scientists for advanced independent careers in research, technology and science education. Understanding the molecular mechanisms by which carbon dioxide modulates stomatal conductance is fundamental to understanding the regulation of gas exchange between plants and the atmosphere, will help to predict effects of atmospheric carbon dioxide elevation on plants, and may also contribute to future engineering of water use efficiency or leaf heat stress avoidance in crop plants and plant carbon sinks in the face of the continuing atmospheric carbon dioxide rise and climate change.