Pytochrome mediates two effects of light on transcription of genes encoding the small subunit of ribulose-1,5-bisphosphate carboxylase-oxygenase in dark-grown pea (Pisum sativum) plants. One response is an initial transient increase in the rate of small subunit gene transcription which results in the accumulation of a small, but relatively stable, amount of small subunit mRNA. The second is the induction of the capacity for high rates of small subunit gene transcription when plants are subsequently illuminated with white light.
