Blue-light regulation of transcription for nuclear genes in pea

The expression of many nuclear genes in plants is light regulated. Previous investigations have shown that the excitation of phytochrome can affect transcription rate and steady-state RNA levels for several of these genes. No direct demonstration of the effects of blue light has been reported. We have identified several nuclear genes in pea whose transcription rate and steady-state RNA levels are affected by a single pulse of blue light. Pea seedlings, grown in continuous red light to saturate any phytochrome response, were treated with a single pulse (10(3) mumol.m(-2)) of blue light 6 days after planting. The blue-light treatment resulted in an increase in the steady-state RNA level and rate of transcription for the Cab (chlorophyll a/b binding protein) gene family and a decrease in the steady-state RNA level and the rate of transcription for the gene families corresponding to cDNA clones pEA25 and pEA207. Changes in the rate of transcription for Cab and pEA207 are apparent within 3 hr of the blue-light treatment.