Genetic Analysis of Blue Light Perception and Signal Transduction Mechanisms in Plants

这项提议的长期目标是在细胞和分子水平上确定蓝光如何被植物感知并转化为生长反应。本项目将以拟南芥为模式系统，研究高等植物蓝光反应的生理和遗传基础。我们将集中讨论的反应是连续蓝光对下胚轴伸长的抑制。具体的目标是分离出一些对蓝光反应发生变化的突变菌株，并使用这些突变菌株来表征信号转导途径的部分，可能是蓝光受体本身。将对突变植物进行生理分析，以确定突变影响反应的哪些阶段。各种蓝光和红光反应之间的相互作用共享信号转导事件。含有两个或两个以上光反应突变的植物将被遗传构建并用于光依赖信号转导网络的研究。蓝光反应突变体将使用互补分析进行遗传特征分析，以确定信号转导涉及的最少步骤。最后，这些突变将被映射到它们的染色体位置，然后使用T-DNA插入突变体或染色体行走进行基因分离，以确定蓝光信号转导所需的蛋白质。光不仅为植物提供光合作用所需的能量，而且几乎独立于光合作用调节植物发育的所有阶段。幼苗要想正常生长，需要许多发育途径的协同作用。光通过几个光感受器系统的作用，触发了幼苗从黑暗土壤中生长到阳光下生长所必需的许多发育变化。红光/远红光受体光敏色素是研究最深入的，而蓝光和紫外光受体的性质几乎是未知的。这项建议旨在确定和研究植物感知和响应蓝光的机制，从而确定植物如何适应不同的光条件。对蓝光响应系统的研究可能导致对控制幼苗建立过程中光形态发生的生理和分子机制的重要的新的见解。

The long-term objectives of this proposal are to determine at the cellular and molecular level how blue light is perceived by plants and transduced into growth responses. This project will investigate the physiological and genetic basis for blue light responses in higher plants using Arabidopsis as a model system. The response we will concentrate on is the inhibition of hypocotyl elongation caused by continuous blue light. Specific goals are to isolate a number of mutant strains that show altered responses to blue light and to use these mutants to characterize portions of the signal transduction pathway, perhaps the blue light receptor itself. Physiological analysis of the mutant plants will be conducted in order to identify what phases of the response are affected by the mutations. Interactions between various blue and red light responses share signal transduction events. Plants containing two or more light-response mutations will be genetically constructed and used in the investigation of the light-dependent signal transduction networks. The blue light-response mutants will be genetically characterized using complementation analysis to determine the minimum number of steps involved in signal transduction. Finally the mutations will be mapped to their chromosome locations followed by gene isolation, using T-DNA insertion mutants or by chromosome walking, in order to identify the proteins required for blue light signal transduction. Light not only supplies plants with the energy for photosynthesis, but also regulates nearly all stages of plant development, independent of photosynthesis. For a seedling to properly establish itself requires the coordinated action of numerous developmental pathways. Light, through the action of several photoreceptor systems, triggers many of the developmental changes essential for seedlings to make the transition from growing in the darkness of the soil to the light of the sun. The red/far red light receptor, phytochrome, has been the most intensively studied, whereas the nature of the blue and ultraviolet receptors is virtually unknown. This proposal seeks to identify and investigate the mechanisms by which plants perceive and respond to blue light and, thus, how plants adapt to different light conditions. The investigation of blue light response systems is likely to lead to important new insights into the physiological and molecular mechanisms controlling photomorphogenesis during seedling establishment.***//