Ethylene is a plant hormone of particular importance in agriculture today because of its many effects on plant growth and development, from seed germination through senescence and death of the plant. Commercial use of ethylene in stimulating plant ripening is currently practiced, despite the fact that little is known about how its natural production by the plant is regulated or how it acts in controlling the plant's growth and maturation. The purification of the enzyme ACC synthase which is primarily responsible for the production of ethylene has been completed. This purification was achieved for the enzyme from mung bean tissue, an excellent system for further studies on the molecular events which surround ethylene formation for the following reasons: the tissue is quickly grown, it can be obtained in large quantity, and it exhibits rapid and large increases in ACC synthase production upon appropriate stimulation. This proposal is designed to address the question of how production of the ethylene-forming enzyme ACC synthase is regulated in mung bean tissue and whether the dominant controls are exerted at the gene expression level. Towards this goal, the molecular events which lead to increased formation of ACC synthase (and therefore of increased ethylene) will be examined. Through the use of antibodies directed against ACC synthase, the extent to which increased gene expression accounts for the elevation in ACC synthase production and how this process is affected by other plant hormones, specifically indole-3- acetic acid and brassinosteroids will be determined. In addition, the gene for ACC synthase in mung beans will be isolated and its DNA sequence determined. This information will greatly assist efforts to understand how the enzyme works in producing ethylene.
