Substitution of Redox Chemicals for Radiation in Phytochrome-Mediated Photomorphogenesis1

Abstract

The reducing agents, potassium ferrocyanide, [beta]-mercaptoethylamine, cysteine, reduced DPN, ferrous sulfate, methyl viologen, and ascorbic acid caused the expansion in darkness of primary leaf tissue disks cut from dark-grown beans. The reducing agents interacted synergistically with low irradiances of red light and additively with high irradiance of red light. Exposure of disks treated with reducing agents to far red light surpressed disk expansion and the decay in sensitivity to far red light showed the same kinetics as sequential exposure to red and far red light. The oxidizing agents, 1,4-naphthoquinone, ferric sulfate, hydrogen peroxide, tertiary butyl hydroperoxide, cystine, and potassium ferricyanide depressed the expansion of leaf disks initiated by red light. The oxidizing agents interacted synergistically with low irradiances of far red light and additively with high irradiances of far red light.