Mechanistic links between phytochrome signaling and chloroplast differentiation

该奖项由2009年美国复苏和再投资法案(公共法律111-5)资助。PI：孟晨，博士论文编号：IOS-0923722题目：光敏色素信号和叶绿体分化之间的机械联系叶绿体分化，或植物在萌发后如何变绿，对于建立使植物进行光合作用的光合体至关重要。因此，在依赖光的植物发育过程中，这是一个必不可少的过程。虽然众所周知，叶绿体的分化主要由红色和远红光受体光敏色素控制，但对光敏色素启动这一过程的分子机制知之甚少。最近，研究人员在模式植物拟南芥中发现了一种新的、与光敏色素信号转导有关的重要成分--HMERA(HMR)。有趣的是，HMR是迄今为止发现的第一个光敏色素信号成分，也是叶绿体分化所必需的。HMR编码一种在陆地植物中高度保守的蛋白质，以前被证明与可塑性转录机制有关。然而，来自研究人员的初步证据表明，HMR应该定位于细胞核。作为该项目的一部分，该研究旨在通过确定HMR的亚细胞定位并结合遗传学、生化和细胞生物学方法定义其定位信号来解决这一困境。这项拟议的研究可能会揭开光敏色素信号与叶绿体分化启动之间的新机制。阐明叶绿体分化的分子机制将有助于我们了解核基因组和细胞器基因组如何协调它们对环境信号的响应，并将对提高农业产量具有深远的意义。此外，拟议的项目将为博士后研究员、研究生和本科生提供出色的分子遗传学方法培训。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).PI: Meng Chen, Ph.D.Proposal Number: IOS-0923722Title: Mechanistic links between phytochrome signaling and chloroplast differentiationChloroplast differentiation, or how plants turn green after germination, is critical to the establishment of photosynthetic plastids that enable plant to undergo photosynthesis. Thus, it is an essential process during light-dependent plant development. Although it is well known that chloroplast differentiation is controlled mainly by the red and far-red photoreceptor phytochromes, little is known about the molecular mechanisms by which phytochromes initiate this process. Recently, the investigators identified a novel and essential component for phytochrome signaling, HEMERA (HMR), in the model plant species Arabidopsis. Interestingly, HMR is the first phytochrome signaling component discovered so far that is also required for chloroplast differentiation. HMR encodes a highly conserved protein in land plants, and was previously shown to be associated with plastidic transcriptional machinery. However, preliminary evidence from the investigators suggests that HMR should be localized in the nucleus. The research undertaken as part of this project aims to solve this dilemma, by determining the subcellular localization of HMR and to define its localization signals using a combination of genetics, biochemical, and cell biological approaches. The proposed research is likely to unravel novel mechanisms linking phytochrome signaling and the initiation of chloroplast differentiation. The elucidation of molecular mechanisms for chloroplast differentiation will contribute significantly to our basic knowledge of how nuclear and organellar genomes coordinate their responses to environmental cues, and will also have deep implications in improving yield in agriculture. In addition, the proposed projects will provide excellent training in molecular genetic approaches for postdoctoral fellows, graduate students, and undergraduate students.