Molecular Genetic Analysis of Spatial-Specific Phytochrome Responses in Arabidopsis Thaliana

该奖项由2009年《美国复苏和再投资法案》(公法111-5)资助。植物不同的器官、组织和细胞对环境信号有不同的反应(例如，在去黄化期间，光刺激子叶生长，而下胚轴生长受光抑制)。器官和组织特定的光吸收光敏色素池启动不同的信号级联，从而影响离散的生理反应，这一假设正在这些研究中得到验证。在这个项目中，一种新的靶向分子方法被用来通过代谢来灭活光敏色素生色团，从而特异性地消耗植物不同细胞和组织中的光敏色素。这种方法是在细胞和组织(即空间特异性)水平上理解光敏色素功能的先决条件，并允许控制植物光敏色素缺乏的严重程度和定位，这是使用经典的突变分离或RNAi技术和表型分析无法实现的。为了确定光敏色素信号的新的空间特异性方面和光形态发生的不同方面的分子基础，将致力于以下目标：(1)与拟南芥脱黄素化的不同方面相关的新的空间特异性光敏色素反应的特征；(2)在目标光敏色素-生色团缺陷系中鉴定负责空间特异性光敏色素反应的分子机制；以及(3)靶向光敏色素-生色团缺陷品系中开花的空间特异性光调控的特征。分子遗传学和基因组学方法正被用来实现这些目标。这些研究的结果有望通过识别特定的细胞机制和候选基因来帮助我们理解高等植物中复杂的光敏色素依赖的信号通路，这些基因参与了光介导的植物生长和发育的不同方面的调控。更广泛的影响：这项研究的重点是提高对胆蛋白调节光形态发生的分子机制的基本理解。这些研究的结果有望对细胞和组织特有的光敏素池的分子基础产生新的见解，这些光敏素池在细胞间发挥作用，协调控制植物生长和发育的不同方面对光的响应，并可能导致改善农业实践，最大限度地依靠光对农学重要植物的生长。除了对研究生和博士后学者的培训外，这些调查的更广泛的影响还包括旨在培养本科生理科专业学生批判性和分析性思维能力的研究经验，以及来自代表性不足群体的学生，包括密歇根州立大学查尔斯·德鲁科学丰富计划的学生和密歇根州立大学植物基因组暑期研究体验计划的参与者。还为博士后助理制定了指导和专业发展计划，以促进对参与的博士后科学家进行全面培训。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Distinct organs, tissues and cells of plants can display different responses to environmental cues (e.g., during de-etiolation cotyledon growth is stimulated by light, whereas hypocotyl growth is inhibited by light). The hypothesis that organ- and tissue-specific pools of light-absorbing phytochromes initiate distinct signaling cascades that effect discrete, physiological responses is being tested in these investigations. In this project, a novel targeted molecular approach is being used to inactivate metabolically the phytochrome chromophore and thereby specifically deplete phytochromes in distinct cells and tissues of plants. Such an approach is a prerequisite for understanding phytochrome functions at the cellular and tissue (i.e., spatial specific) level and allows control over the severity and localization of phytochrome deficiency in plants that is not achievable using classical mutant isolation or RNAi technology followed by phenotypic analyses. To identify novel spatial-specific aspects of phytochrome signaling and the molecular bases of distinct aspects of photomorphogenesis, the following objectives will be pursued: (1) the characterization of novel spatial-specific phytochrome responses associated with distinct aspects of de-etiolation in Arabidopsis thaliana; (2) the identification of molecular mechanisms responsible for spatial-specific phytochrome responses in targeted phytochrome-chromophore deficient lines; and (3) the characterization of spatial-specific photoregulation of flowering in targeted phytochrome-chromophore deficient lines. Molecular genetic and genomic approaches are being utilized to accomplish these objectives. The results from these studies are expected to contribute significantly to our understanding of the complex phytochrome-dependent signaling pathways that operate in higher plants through the identification of specific cellular mechanisms and candidate genes involved in the regulation of distinctive aspects of light-mediated growth and development in plants. Broader Impacts: This research focuses on improving fundamental understanding of molecular mechanisms of biliprotein-regulated photomorphogenesis. Results from these studies are expected to yield novel insight into the molecular bases of cell- and tissue-specific pools of phytochromes that work intercellularly to coordinately control distinctive aspects of plant growth and development in response to light and may lead to improved agricultural practices for maximizing light-dependent growth of agronomically important plants. In addition to the training of graduate students and postdoctoral scholars, broader impacts of these investigations include research experiences designed to develop the capacity to think critically and analytically of undergraduate science majors and students from underrepresented groups, including students in the Charles Drew Science Enrichment Program at Michigan State University and participants in the MSU Plant Genomics Summer Research Experience for Undergraduates Program. A mentoring and professional development plan for postdoctoral associates also has been developed to promote the comprehensive training of participating postdoctoral scientists.