Phytochrome in cultured wild carrot tissue. I. Synthesis.

Stable levels of P(FR) occur in light-grown suspension cultures of wild carrot. Upon darkening such tissue, P(R) accumulates until the high P(R) level characteristics of dark-grown tissue is reached. Data are compatible with the idea of an equilibrium between processes of synthesis and destruction in tissue grown in the light. Reappearance of phytochrome also follows light-induced pigment destruction in dark-grown tissue. The rate of P(R) appearance is similar in both cases. The rate of disappearance of P(FR), however, is slower in light-grown tissue than in dark-grown tissue.