9416035 Sutton The long-term objective of the proposed research is to identify signal transduction components involved in plant response to environmental stimuli. Using the Xenopus oocyte/mRNA injection system, research proposed will focus on signal transduction in response to the environmental stimuli of low non-freezing temperature and dehydration in higher plants. A common effect of these two stimuli on plants is to modulate endogenous abscisic acid (ABA) levels, not all responses to low temperature are ABA dependent. The mode of action of ABA has not been conclusively demonstrated. Questions remain regarding actual location of ABA receptors, and second messengers, if any, that are necessary for signal transduction. Research proposed will initially focus on ABA, since there is evidence in the literature of ABA stimulating Ca release. Preliminary data from this lab suggests that ABA may interact with plasma membrane receptors and cause an increase in intracellular Ca. Specific aims of this proposal are: 1) To characterize the responses, to ABA and several ABA analogues, from oocytes injected with tobacco mRNA. 2) If Ca is mobilized, to localize its source in an attempt to determine the manner in which ABA and its receptors are functioning. If Ca is not mobilized, to determine the alternative second messenger system being utilized by ABA. 3) To utilize the Xenopus oocyte system to isolate and characterize ABA receptors cDNA clones. Knowing how ABA and receptor(s) interact will help in understanding plant responses common to the stimuli of low temperature and dehydration. Research proposed will involve the areas of electrophysiology, molecular biology, biochemistry and cell biology. The integrative nature of this research will make it possible for research to be performed at appropriate collaborative research laboratories and will prove to be a rewarding and exciting environment for training of postdoctoral associates and graduate students. ** *
