LIGHT-RESPONSIVE GENES

植物依赖于光作为信号来调节两者 发育和代谢过程，光敏色素被认为是 调节这些反应的主要植物光感受器。 很长的- 我们实验室的长期目标是确定 光敏色素信号通路，并了解这些通路是如何 监管. 通过建立一个基于显微注射的实验系统， 已经证明存在三种信号转导途径， 是下游的光敏色素（PHYA）之一，并调节 编码叶绿体组分和花青素的基因的表达 生物合成酶 一种途径依赖于钙， 第三种作用于这两种效应物。 我们有 建立了CAB、CHS和FNR作为活性的特异性报告基因 三个PHYA信号通路的每一个。 我们现建议 使用四种方法进一步研究这些途径：A） 鉴定CAB、CHS和FNR启动子内的单个顺式元件 能对钙和/或cGMP产生反应 这项工作将由 显微注射实验使用各种启动子缺失和合成 含有一个或多个先前鉴定的顺式元件的启动子。 我们 注意力将集中在转录因子的结合位点上 CAB启动子中的GT-1，以及G盒和Myb因子结合位点 在CHS启动子中。B）除了PHYA信令之外 中间体已经阐明，我们希望使用我们的显微注射 技术来描述别人。 特别是，我们将研究 钙/钙调蛋白依赖性蛋白激酶II可能参与 和鸟苷酸环化酶。C）在拟南芥中使用突变体分离筛选 基于光调节报告基因（CAB-1）的异常表达， LUC）对光的反应，我们已经分离出许多突变体， 改变PHYA信号转导。 光生物学与PHYA 突变表型的依赖性将被表征，并且那些清楚地 影响PHYA信号转导将进行分析，以确定 信号通路中的病变部位。D.根据最近 实验我们现在有一些了解如何个人PHYA信号 通路的调节，以及每个通路之间的串扰机制 手术。 我们设计了新的筛选策略， 这种调节机制，基于CAB的异常表达， LUC报告基因或CHS-LUC报告基因，其最近已被 在我们的实验室里插入拟南芥基因组。 使用这些 方法，我们希望扩大我们的知识，不仅是过程， 植物通过光敏色素感知光线， 调节基因表达的过程， 光敏色素

Plants are dependent upon light as a signal for regulating both developmental and metabolic processes, and phytochrome is held to be the principal plant photoreceptor that regulates these responses. The long- term objective of our laboratory is to identify the components of phytochrome signaling pathways and to understand how these pathways are regulated. By developing a microinjection-based experimental system, we have demonstrated the existence of three signal transduction pathways that are downstream of one of the phytochromes (PHYA), and which regulate the expression of genes encoding chloroplast components and anthocyanin biosynthetic enzymes. One pathway is dependent upon calcium, the second upon cGMP, and the third upon both of these effectors. We have established CAB, CHS, and FNR, as specific reporter genes for the activity of each of the three PHYA signaling pathways respectively. We now propose to investigate these pathways further using four approaches: A) To identify individual cis-elements within the CAB, CHS and FNR promoters that can respond to calcium and/or cGMP. This will be carried out by microinjection experiments using various promoter deletions and synthetic promoters containing one or more previously identified cis-elements. Our attention will be focused on binding sites for the transcription factor GT-1 in the CAB promoter, and on G-boxes and Myb-factor binding sites within the CHS promoter. B) In addition to the PHYA signaling intermediates already elucidated, we hope to use our microinjection techniques to characterize others. In particular, we will examine the possible participation of calcium/calmodulin-dependent protein kinase II and guanylyl cyclase. C) Using a mutant isolation screen in Arabidopsis based upon the aberrant expression of a photoregulated reporter gene (CAB- LUC) in response to light, we have isolated a number of mutants which may be altered in PHYA signal transduction. The photobiology and PHYA dependency of mutant phenotypes will be characterized and those clearly affected in PHYA signal transduction will be analyzed to determine the sites of lesions within the signaling pathways. D) Based upon recent experiments e now have some understanding of how individual PHYA signaling pathways are regulated, and how cross-talk mechanisms between each pathway operate. We have devised new screening strategies to isolate mutants in such regulatory mechanisms, based upon the aberrant expression of the CAB- LUC reporter gene or a CHS-LUC reporter gene which has recently been inserted into the Arabidopsis genome in our laboratory. Using these approaches we hope to expand our knowledge not only of the processes by which plants perceive light via phytochrome, but also the regulatory processes which operate to coordinate the expression of genes regulated by phytochrome.