Calmodulin antagonists inhibit the phytochrome‐induced appearance of two nuclear encoded transcripts in radish cotyledons

The effects of two calmodulin antagonists on the phytochrome-mediated appearance of two nuclear encoded transcripts in radish cotyledons have been investigated. The extent of inhibition of transcript accumulation was dependent of the time ellapsed between the administration of trifluoperazine and the light stimulus. When 1 mM trifluoperazine was administered to the seedlings 8 h before red light irradiation, the inhibition of transcript accumulation was up to 62% for the chlorophyll binding protein mRNA and 56% for the ribulose 1,5-bisphosphate carboxylase small subunit mRNA. Similar results were obtained with W-7 (0.1 mM).