Molecular Genetic and Cellular Analysis of Light Response inMaize Leaf Cells

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9407834 Sheen Light regulates many aspects of plant growth and development among which the conversion of dark-grown etiolated leaves to photosynthetic competent green leaves (greening) is most essential to plant life and best documented in higher plants. Although both red and blue light photoreceptors, phytochrome and cryptochrome, have been implicated in light signal perception, very little is known about the molecular basis of the intracellular signal transduction pathways mediating the light-inducible developmental processes marked by chlorophyll accumulation and photosynthetic gene activation. We are interested in elucidating the molecular mechanisms mediating light responses in leaf cells by combining the genetic power with other biochemical, cellular and molecular approaches offered by the maize experimental system. We will investigate systematically maize mutants that are defective in light-inducible gene expression and chloroplast biogenesis. A versatile and powerful singlecell transient expression system will be used to clone and characterize regulatory genes controlling light-inducible gene expression and chloroplast biogenesis which are cell autonomous activities. The studies will facilitate our understanding of photosynthetic functions and signal transduction in higher plants. %%% Light regulates many aspects of plant growth and development among which the conversion of dark-grown etiolated leaves to photosynthetic competent green leaves (greening) is most essential to plant life and best documented in higher plants. Although both red and blue light photoreceptors, phytochrome and cryptochrome, have been implicated in light signal perception, very little is known about the molecular basis of the intracellular signal transduction pathways mediating the light-inducible developmental processes marked by chlorophyll accumulation and photosynthetic gene activation. We are interested in elucidating the molecular mechanisms mediating light respo nses in leaf cells by combining the genetic power with other biochemical, cellular and molecular approaches offered by the maize experimental system. We are planning to analyze systematically the existing maize photosynthetic mutants by RT-PCR and protoplast transient expression assays. We will make expression cDNA library and conduct pilot experiments to explore the possibility of complementing mutants using the protoplast transient expression assay. New cell surface reporter genes and fluorescence activated protoplast sorting techniques which offer the efficiency and high resolution for expression cloning and mutant complementation will be tested. It is likely that the system will serve as an excellent tool to unravel unexpected new insights into the molecular mechanisms of light signal transduction and gene regulation in higher plants. ***