Modulation of RNA processing by abscisic acid

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The phytohormone abscisic acid (ABA) regulates various developmental and stress-induced processes in plants. Several ABA response genes encode for RNA-binding or RNA-processing proteins, and recent studies on Arabidopsis ABA-sensitivity mutants have shown ABA involvement in post-transcriptional mRNA processing. Arabidopsis genome encodes more than 200 putative RNA-binding proteins; half of which are plant-specific. RNA-binding proteins mediate mRNA synthesis, splicing, transport, translation and degradation and by influencing transcript abundance, RNA-binding proteins provide a major regulatory role in fine-tuning cellular protein expression.Our knowledge of plant RNA-binding proteins is very limited and only a few plant RNA-binding proteins are characterized, with little or no information available on the mechanism by which their action is regulated. Most of the studied RNA-binding proteins in plants are directly or indirectly linked to ABA.I have identified the RNA binding protein, Flowering Time Control Locus A (FCA), as the first ABA receptor in plants and provided the first direct link of a plant hormone to RNA processing.Through this research program, I seek to understand the mechanisms by which ABA regulates RNA processing in plant cells. The objectives of this research are to investigate possible involvement of ABA in regulating RNA processing, determining of RNA binding specificity, and in the interactions of the RNA-binding proteins. This research will comprise both in vivo and in vitro studies, utilizing two ABA receptor proteins, the Arabidopsis FCA and its cereal homologue, ABAP1. My research program will contribute to the existing knowledge on the mechanisms that regulate gene expression and will be the first to look at hormonal regulation of RNA metabolism in plants. My research progrm will have immediate and far-reaching impacts on the fundamental processes of plant growth and development, and can be applied to select for agriculturally important crops that possess high-yield potential and exert high tolerance to biotic and abiotic stresses.