Molecular Genetic and Cellular Analysis of Light Response inMaize Leaf Cells

9407834光泽光调节植物生长发育的许多方面，其中暗生黄化叶片向光合能力强的绿叶（绿化）的转化是植物生命中最重要的，在高等植物中得到了最好的记录。虽然红色和蓝色光感受器光敏色素和隐色素都与光信号感知有关，但对于介导以叶绿素积累和光合基因激活为标志的光诱导发育过程的细胞内信号转导途径的分子基础知之甚少。我们有兴趣通过结合玉米实验系统提供的其他生化、细胞和分子方法来阐明介导叶片细胞光响应的分子机制。我们将系统地研究在光诱导基因表达和叶绿体生物发生方面存在缺陷的玉米突变体。一个多功能的单细胞瞬时表达系统将用于克隆和表征控制光诱导基因表达和叶绿体生物发生的调控基因，这是细胞的自主活动。这些研究将有助于我们对高等植物光合功能和信号转导的认识。光调节植物生长发育的许多方面，其中暗生长的黄化叶片向具有光合作用的绿叶（绿化）的转化是植物生命中最重要的，在高等植物中得到了最好的证明。虽然红色和蓝色光感受器光敏色素和隐色素都与光信号感知有关，但对于介导以叶绿素积累和光合基因激活为标志的光诱导发育过程的细胞内信号转导途径的分子基础知之甚少。我们有兴趣通过结合玉米实验系统提供的其他生化、细胞和分子方法来阐明介导叶片细胞光响应的分子机制。我们计划通过RT-PCR和原生质体瞬时表达分析系统地分析现有的玉米光合突变体。我们将构建表达cDNA文库并开展中试实验，探索利用原生质体瞬时表达法进行突变体互补的可能性。新的细胞表面报告基因和荧光激活原生质体分选技术将为表达克隆和突变体互补提供高效率和高分辨率。该系统很可能为揭示高等植物光信号转导和基因调控的分子机制提供一个很好的工具。＊＊＊

9407834 Sheen Light regulates many aspects of plant growth and development among which the conversion of dark-grown etiolated leaves to photosynthetic competent green leaves (greening) is most essential to plant life and best documented in higher plants. Although both red and blue light photoreceptors, phytochrome and cryptochrome, have been implicated in light signal perception, very little is known about the molecular basis of the intracellular signal transduction pathways mediating the light-inducible developmental processes marked by chlorophyll accumulation and photosynthetic gene activation. We are interested in elucidating the molecular mechanisms mediating light responses in leaf cells by combining the genetic power with other biochemical, cellular and molecular approaches offered by the maize experimental system. We will investigate systematically maize mutants that are defective in light-inducible gene expression and chloroplast biogenesis. A versatile and powerful singlecell transient expression system will be used to clone and characterize regulatory genes controlling light-inducible gene expression and chloroplast biogenesis which are cell autonomous activities. The studies will facilitate our understanding of photosynthetic functions and signal transduction in higher plants. %%% Light regulates many aspects of plant growth and development among which the conversion of dark-grown etiolated leaves to photosynthetic competent green leaves (greening) is most essential to plant life and best documented in higher plants. Although both red and blue light photoreceptors, phytochrome and cryptochrome, have been implicated in light signal perception, very little is known about the molecular basis of the intracellular signal transduction pathways mediating the light-inducible developmental processes marked by chlorophyll accumulation and photosynthetic gene activation. We are interested in elucidating the molecular mechanisms mediating light respo nses in leaf cells by combining the genetic power with other biochemical, cellular and molecular approaches offered by the maize experimental system. We are planning to analyze systematically the existing maize photosynthetic mutants by RT-PCR and protoplast transient expression assays. We will make expression cDNA library and conduct pilot experiments to explore the possibility of complementing mutants using the protoplast transient expression assay. New cell surface reporter genes and fluorescence activated protoplast sorting techniques which offer the efficiency and high resolution for expression cloning and mutant complementation will be tested. It is likely that the system will serve as an excellent tool to unravel unexpected new insights into the molecular mechanisms of light signal transduction and gene regulation in higher plants. ***