This award will facilitate collaboration under the U.S.-Japan Cooperative Science Program on a project concerned with the role of ethylene as a plant hormone which regulates many aspects of plant growth and development, including fruit ripening, leaf senescence, and flower fading. The chemical precursor of ethylene in plants is the compound 1- aminocyclopropane-1-carboxylic acid (ACC). This compound in turn is produced from S-adenosylmethionine (SAM). The rate- limiting step in ethylene biosynthesis in plants has been shown to be the conversion of SAM to ACC, catalyzed by the enzyme known as ACC synthase. It is the study of this enzyme, isolated from plant tissues, that forms the subject of this cooperative project. It is known that various developmental, hormonal, and environmental factors, such as auxin treatment or plant wounding, cause the induction of ACC synthase, resulting in marked increase in ethylene production. However, the ACC synthase induced in these different ways appears to show differences in its immunological and physicochemical properties. The goal of this research is to elucidate, at both the protein and gene levels, the comparative biochemistry of ACC synthase induced in different tissues by different factors. The U.S. principal investigators in this project are Dr. Shang Fa Yang and Dr. Alan B. Bennett, Department of Vegetable Crops, University of California, Davis. Their Japanese colleagues are Dr. Hidemasa Imaseki, Nagoya University, and Dr. Shigeru Satoh, Tohoku University. The U.S. group is working with tomato and apple, and the Japanese group is studying the same process in squash and other plants. Purified materials isolated by the two groups will be exchanged and tested, and information and expertise will be shared. Results obtained during these studies should lead to further understanding of those basic plant processes regulated by ethylene. This knowledge can potentially be exploited in the control of these processes via biotechnology, with resulting significance in agriculture.
