Mechanism(s) of Plant Response to Suboptimal and Adverse Irradiance

光照胁迫直接影响植物叶绿体中光系统的结构。这些调节显然有助于优化光合作用，并允许植物在次优和/或不利的光照条件下保持高效生长。这项研究的总体目标是了解植物对次优和不利辐射反应的基本机制。将研究在叶绿体中发现的类囊体膜的成分。这一建议的具体目标是确定信号的主要受体(辐射胁迫)，并阐明导致植物反应的信号转导和转换过程的第一步。将采用的实验方法和途径包括吸光度差分光光度法、凝胶电泳和免疫印迹(WESTERN)分析、放射性标记和放射自显影以及DNA-RNA杂交(Northern分析)。这项研究提出了一种新的观点，即光合色素在逆光照识别的第一步中起作用，信号转导是由类囊体膜上的电子传递反应介导的。有初步证据表明，这种分子反馈控制机制指导植物对辐射胁迫的反应，这一建议将检验这一机制。这项研究的结果将加深我们对光合作用植物感知和适应包括紫外线辐射(UV-B)在内的辐射胁迫的机制的理解。这将对预测植物对大气中平流层臭氧耗尽可能导致的UV-B潜在增加的反应产生影响。

Irradiance stress directly affects the structure of the photosystems in plant chloroplasts. These adjustments apparently help optimize photosynthesis and allow the plant to retain efficient growth under suboptimal and/or adverse irradiance conditions. The overall goal of this research is to understand the fundamental mechanism of plant response to suboptimal and adverse irradiance. Components of thylakoid membranes which are found in chloroplasts will be studied. Specific goals of this proposal are to identify the primary receptor of the signal (irradiance stress) and elucidate the first step in the signal transduction and transformation process leading to a plant response. Experimental methodologies and approaches to be employed include absorbance difference spectrophotometry, gel electrophoresis and immunoblot (western) analysis, radioactive labelling and autoradiography, and DNA-RNA hybridization (northern analysis). This research addresses a novel idea, namely that photosynthetic pigments act in the primary step of adverse irradiance recognition and that signal transduction is mediated by electron transport reactions in the thylakoid membrane. There is preliminary evidence to suggest that such a molecular feedback control mechanism guides plant response to irradiance stress and this proposal will examine this mechanism. Results from this research will improve our understanding of the mechanisms by which photosynthetic plants perceive and adapt to irradiance stress including ultraviolet radiation (UV-B). This will have implications for predicting plant response to potential increases in UV-B that may result from depletion of stratospheric ozone in the atmosphere.