Phytochrome appearance and distribution in the embryonic axis and seedling of Alaska peas.

Apparent synthesis of phytochrome has been observed in the embryonic axis of germinating Alaska pea and in the young seedling. The onset of photoreversibility can be delayed, and the amount of phytochrome appearing in a plant of a given size somewhat decreased, by treatment with cycloheximide in appropriate concentrations. Similar concentrations of cycloheximide also reduce elongation. Soaking seeds in water at 4° for 24 hr also prevents the onset of photoreversibility in the embryonic axis. The pattern of phytochrome appearance, and the distribution of relative amounts of phytochrome, suggest that synthesis may be closely related to general protein synthesis during elongation.