Regulatory and Signaling Mechanisms of Crassulacean Acid Metabolism: A Photosynthetic Adaptation to Environmental Stress

该奖项是根据2009年《美国复苏和再投资法案》(公法111-5)资助的。景天酸代谢是一种光合作用途径，存在于大约7%的维管植物物种中，与C3物种相比，其水分利用效率提高了10倍，为昼夜节律和环境调节的光合作用适应提供了一个很好的例子。CaM植物表现出独特的昼夜节律输出和逆气孔节律，这是C3或C4植物所没有的。这项研究的长期目标是确定分别对CAM和逆气孔行为的昼夜节律控制至关重要的调节和信号通路。普通或结晶型冰草将作为模型，通过进行mRNA表达谱来确定C3光合作用向CAM过渡过程中环境诱导的、昼夜节律控制的mRNA和蛋白质丰度的变化，以及可逆的蛋白质磷酸化事件。代谢物的变化也将被监测，以确定它们是否参与上游生物钟基因表达输出的可能反馈控制电路。还将分析在CAM昼夜节律时钟中起作用的关键调节和信号因素。对控制CAM表达和调控的分子机制的进一步了解将提供关于这种重要的节水光合作用适应的分子基础的新知识，这将为在全球气候变化的背景下提高作物生产力提供新的策略。该项目将为本科生、研究生和博士后提供独特的植物研究实践培训机会。本科生将从内华达大学(UNR)已建立的推广计划中挑选出来，这些计划针对弱势背景的学生，参与开发“植物有节奏”教育展示和K-12教学模块，以告知和激发高中、大学生和普通公众关于CAM和植物昼夜节律的存在及其适应意义的知识。

"This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5)." Crassulacean acid metabolism (CAM), a photosynthetic pathway found in approximately 7% of all vascular plant species that improves water use efficiency up to 10-fold relative to C3 species, provides an exquisite example of circadian and environmentally regulated photosynthetic adaptation. CAM plants display distinctive circadian clock outputs and inverse stomatal rhythms, which are not found in C3 or C4 plants. The long-term goals of the proposed research are to identify the regulatory and signaling pathways essential for the circadian control of CAM and inverse stomatal behavior, respectively. The common or crystalline ice plant will be used as a model to determine the environmentally induced, circadian controlled changes in mRNA and protein abundance, and reversible protein phosphorylation events during the transition from C3 photosynthesis to CAM by conducting mRNA expression profiling. Metabolite changes will also be monitored to determine if they participate in possible feedback control circuits of upstream circadian clock gene expression outputs. Key regulatory and signaling factors that function in the CAM circadian clock will also be analyzed. Increased understanding of the molecular mechanisms responsible for controlling the expression and regulation of CAM will provide new knowledge about the molecular basis of this important water-saving photosynthetic adaptation that will provide novel strategies for improving crop productivity in the context of global climate change.This project will provide unique 'hands-on' training opportunities in plant research for undergraduate, graduate and post-doctoral students. Undergraduate students will be selected from established outreach programs at the University of Nevada (UNR) that target students from disadvantaged backgrounds to participate in developing a "Plants Have Rhythm" educational display and K-12 teaching module to inform and excite high school, college students, and the general public about CAM and the existence of circadian rhythms in plants and their adaptive significance.