Photochemical and Nonphotochemical Reactions of Phytochrome in vivo

Abstract
The nonphotochemical reactions of phytochrome in the coleoptiles of dark-grown corn seedlings were studied at 3 temperatures: 14°, 24°, and 34°. The data obtained show that the destruction of Pfr is the only measurable reaction occurring; reversion of Pfr to Pr was not found. The Q10's (2.7 and 3.5) and zero order kinetics found for the destruction reaction are consistent with the hypothesis that the reaction is enzyme-mediated.