Molecular Genetic Dissection of Red/Far-Red Light Signaling Pathways in Maize

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Recent studies in the model plant Arabidopsis thaliana have greatly expanded our understanding of the complex light signal transduction networks mediating a range of developmental and environmental responses. However, as studies rapidly progress in Arabidopsis, our knowledge of this complex pathway in the distantly related monocots is far less complete. Differences in phytochrome gene family organization, plant physiology and selection pressures have likely contributed to the divergence of light signal transduction pathways between higher eudicots such as Arabidopsis thaliana and monocotyledonous grasses such as Zea mays. The goal of this project is to begin the detailed characterization of red/far-red light signaling pathways in maize utilizing classical and reverse genetics strategies, molecular genetic analyses and microarray technologies. A comprehensive analysis of phytochrome gene family structure and expression in maize will be conducted as an important first step in the analysis of light signaling pathways in maize. Through tools developed by NSF- and government-funding genomics initiatives, transposon-tagged alleles have been identified in two of the three phytochrome gene family members in maize. Genetic and molecular characterizations of these mutants will include the use of microarray technology to compare nuclear and chloroplast gene expression profiles in wild type and these phyA and phyB mutants under a range of light conditions. Finally, red/far-red light responses will be examined in a core set of 80 US, Canadian, European, and South American accessions that best represent diversity in the maize germplasm pool. These studies should provide insights into the underlying genetic diversity regulating light responses in maize.