Characterization of GC ABA Receptor Coupled to KAT1 Expressed in Xenopus Oocytes

South Dakota State University, Brookings SD

Investigators

Abstract

Urbanization, flooding, drought and salinization of soil are diminishing landmass needed to supply food for an expanding world population. Together with contined global efforts to safeguard agricultural land for future food production, it is important to understand how plants function so that they can be bred or modified to survive the harsher environments. A critical aspect of plant function is ion, water and nutrient movement across membranes. This research focuses on receptors, ion channels, transporters and the mechanism(s) by which they are regulated. The Xenopus oocyte system is used for functional expression of plant mRNA. The source of mRNA is guard cells because they play a critical role in controlling water loss and gaseous exchange. V. faba is the experimental plant choice because research on ion channel and signal transduction of V. faba guard cells is extensive. The two electrode voltage clamp (TEVC) technique is used for the assay. Preliminary results have shown that oocytes injected with V. faba guard cell mRNA (GC mRNA) express a GC specific ABA receptor that inhibits activity of the inward rectifying K + channel, KAT1. This research will test the hypothesis that: ABA modulation of KAT1 is via an extra-cellular facing plasma membrane receptor. A cDNA clone for this receptor will be isolated. The identification of a GC-specific ABA receptor will lead to the identification of one sub-type of the ABA receptor. It may be possible by conservation of homology among receptors to isolate the other subtypes. Sequencing information from the isolated clones will allow use of bioinformatics to identify other proteins in the databases with related functions. The long-term goal of this research is to understand how ABA controls ion uptake during the exchange of water and carbon dioxide in photosynthesis. The research outlined will permit student training in molecular biology, electrophysiology and bioinformatics. The identified plant genes will provide targets for genetic modification and herbicide or chemical manipulation of plant function, thus allowing plants to survive in inhospitable environmental conditions.