9511623 Wang Lipid-based signaling via the octadecanoid pathway, which leads to the formation of regulators such as jasmonic acid, plays an important role in plant physiological processes. Jasmonate and related oxygenated lipids have been shown to act as endogenous signals activating defense gene expression and regulating growth and development. Alph-linolenic acid has been shown to be the precursor for the synthesis of these regulators. However, very little is known about lipolytic release of alpha-linolenic acid in the octadecanoid signaling pathway. Which lipid hydrolyzing enzyme is activated in the signaling process? Which glycerolipids are hydrolyzed? How is the hydrolysis regulated? These questions are important because making available the fatty acid precursor is an early step in the sequence of events in signal transduction and may control the signaling pathway. The goal of this research is, therefore, to investigate the involvement, nature, and regulation of deacylation by lipolytic enzymes in the octadecanoid signaling pathway. Stimulus-induced lipid turnover and release of alpha-linolenic acid will be investigated in castor bean leaves in response to wounding. Wounding is chosen because it is a well characterized stimulus that induces the jasmonate signaling system. Completion of the proposed work will fill a critical gap in our knowledge of the cellular roles of membrane lipid-hydrolyzing enzymes in plant growth and environmental responsiveness.
