9603418 Sun This award supports a three year collaborative research project between Professor Tai-ping Sun of Duke University in North Carolina and Dr. Yuji Kamiya of the Institute of Physical and Chemical Research (RIKEN) in Saitama, Japan. The project is a study of the regulatory mechanisms of gibberellin biosynthesis and response in Arabidopsis. Gibberellins (GAs) are diterpenoid compounds, some of which are plant growth regulators, controlling such diverse processes as seed germination, stem elongation, and flower development. There are three major goals of this project: 1) examine the effect of light on the expression of the first gene (GA1) in the Arabidopsis GA biosynthetic pathway to understand how light regulates GA concentrations in responding tissues; 2) examine the effects of overproduction of the first two enzymes (ent- kaurene syntheses A and B) in the GA biosynthetic pathway on plant growth; and 3) measure the GA content of new GA-response mutants that have been isolated to determine whether these mutations alter GA metabolism. The project brings together the efforts of two laboratories that have constituted different parts of the process: the Americans will provide the new GA-response mutants and the Japanese will perform the GA measurements. The results of this project will identify regulatory mechanisms of GA biosynthesis and organ-specific GA responses that are now unclear. Through the exchange of ideas and technology, this project will broaden our base of basic knowledge and promote international understanding and cooperation.
