This project is aimed toward the elucidation of intracellular signalling pathways that involve calcium in the transduction of hormonal and environmental stimuli in higher plants. The current project focuses on the part of the signal transduction pathway that involves the interaction between calcium and calmodulin, and the consequent activation of specific target enzymes. The preliminary work for this project established the existence of four different calmodulin isoforms encoded by at least six different genomic DNA sequences from Arabidopsis thaliana. This diversity of calmodulin isoforms is unprecedented in either the plant or animal kingdoms, and preliminary phylogenetic analyses suggest that this arrangement may be unique to Arabidopsis or to the crucifer family. These findings have led to the hypothesis that the different Arabidopsis calmodulin isoforms have evolved to optimize the interaction of calmodulin with specific target enzymes, particularly target enzymes associated with membranes. %%% This project is directed toward intracellular signal transduction pathways in higher plants. At present, there is only a general understanding of these processes in the plant kingdom. The preliminary data demonstrate the existence of multiple isoforms of the calcium-binding elicitor protein, calmodulin, in Arabidopsis thaliana. This unexpected result may underlie significant differences between plants and other organisms in the mechanisms of signal reception and transduction.
