Hormone and stress-regulated gene expression in plants

-Amylase in action. Scanning EM of starch granules form barley seed being digested (holes in surface) by -amylase which is regulated by plant hormones, gibberellins and abscisic acid

"ABA Response Complexex (ABRCs): promoter switches which are necessary and sufficient for ABA induced gene expression"

We are interested in the regulation of gene expression in higher plants under the influence of hormones and environmental stress conditions. Our current research projects include the following: 1) Hormonal control of enzyme synthesis in the aleurone lay ers of germinating cereal grains. In this project we study the mechanisms regulating the expression of genes encoding a-amylases, proteases and nuclease which are regulated by two plant hormones, gibberellic acid (GA) and abscisic acid (ABA). We follow both biochemical and genetic approaches to investigate the structure and function of these genes and their products (e.g. mRNA and proteins). We are currently investigating the transacting factors which interact with specific regions in the a-amylase and protease gene promoters. Future work includes the cloning of cDNA encoding these factors and study of how hormones affect their levels and/or activities. We also plan to use genetic mutants with altered hormone sensitivities to further elucidate the ac tion of these hormones. 2) Control of stress-induced gene expression. We are particularly interested in the synthesis of drought and heat stress induced proteins in corn and barlev. We have centered our efforts around three stress proteins: A nuclear e ncoded, chloroplast-localized heat shock protein, a drought stress/ABA-induced protein with amphipathic a-helical structures, and a drought/ABA-induced protein with features that resemble many regulatory proteins. We are investigating the physiological r oles of these proteins as well as the biochemical mechanisms regulating their synthesis. Several questions are addressed: How is the stress signal perceived by the cells? How are the genes encoding stress proteins turned on by the perceived signal? Ca n the stress proteins protect the cells from being injured by stressful conditions? We are currently studying the role of stress proteins by altering their expression levels in transgenic plants.