Regulation of phytochrome A mRNA abundance in parsley seedlings and cell-suspension cultures.

A cDNA clone encoding the apoprotein of a parsley phytochrome was isolated and classified as parsley PHYA phytochrome, on the basis of a sequence homology comparison with all available phytochrome sequences. Red light pulses led to a phytochrome-dependent down-regulation of PHYA mRNA abundance in etiolated parsley seedlings to a level of 10-20% compared with the dark control. The PHYA mRNA abundance in a parsley cell suspension culture was also down-regulated by light pulses. Transient expression assays in parsley protoplasts showed light regulation of a chimeric pea PHYA promoter uidA-gene construct.