Dependence of phytochrome dark reactions on the initial photostationary state

摘要

Under conditions of continuous irradiation, thePjrdestruction rate constants (kd) of phytochrome in hooks and cotyledons of squash (Cucurbita pepoL.) seedlings do not depend on the photostationary state ϕλand are the same in both organs. On the other hand, the rate constants of the dark reversion and the first destruction step, plotted as a function of ϕλ0, show optimum curves with maxima between ϕλ0and 0.5. Similar results were obtained for dark reactions of mustard (Sinapis albaL.)-hook phytochromein vivo. This indicates a cooperative behaviour of these phytochrome dark reac