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

Michigan State University, East Lansing MI

Investigators

Abstract

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.