Substitution of redox chemicals for radiation in phytochrome-mediated photomorphogenesis.

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