Phytochrome control of multiple transcripts of the phytochrome gene in Pisum sativum.

The reversible effect of red and far-red light on the level of two RNA transcripts of the single-copy phytochrome gene in pea was investigated using the primer extension assay. In dark-grown seedlings, a brief irradiation with red light markedly reduced the level of one of the phytochrome transcripts, RNA1. This red light effect was reversed by subsequent irradiation with far-red light. The other phytochrome transcript, RNA2, was only slightly influenced by light. In light-grown seedlings, a brief irradiation with far-red light increased the content of both RNA1 and RNA2 when the seedlings were transferred from light to darkness. This far-red light effect was reversible by subsequent red light irradiation.