43 真菌Botrytis cinereaによる植物ホルモン アブシジン酸の生産 : 青色光の促進効果と生合成の律速段階について(口頭発表の部)

抄録

We have found that B. cinerea, a phytopathogenic fungus, produces abscisic acid (ABA), a plant hormone. The production of ABA by B. cinerea was enhanced by irradiating blue light (450nm) on the growing colony, whereas an irradiation of near UV light (352nm) decreased the yeild severely. Effects of quality of light on the ABA production were examined with blue light-sensitive strains that were selected by the monospore culture method. Blue light was the most stimulative, red light considerably and far-red light stimulated very slightly, however, near UV and green lights showed no activity.As an energy of blue light was strengthened, the yield of ABA increased, hence, blue light seems to operate as an energy source of its production. In order to clarify what step of enzyme reaction is stimulated by blue light in the biosynthesis of ABA, HMG-CoA reductase, which catalyzed a conversion of HMG-CoA to Mevalonic acid, was measured using the mycelial homogenates. There was a close positive correlation between enzyme activity and ABA production, and as the enzyme activity was enhanced by blue light irradiation, the ABA production increased in a similar rate. Thus, HMG-CoA reductase has been shown to be a rate-limiting enzyme and stimulated by blue light irradiation in the biosynthesis of ABA in B. cinerea.