RHYTHMIC REGULATION OF THE LIGHT-HARVESTING CHLOROPHYLL alb PROTEIN and THE SMALL SUBUNIT OF RIBULOSE-1,5-BISPHOSPHATE CARBOXYLASE mRNA IN RYE SEEDLINGS

In etiolated rye seedlings transferred to light the expression of chlorophyll a/b binding protein mRNA varies when the seedlings are grown in a day/night cycle. The fluctuation pattern follows a circadian rhythm. Exposure of 4-day old etiolated seedlings to continuous white light revealed two maxima within the first 24 h before the 24 h cycle period appeared. These first two maxima are also observable after a pulse of white light or after a pulse of red light. These results indicate a possible involvement of phytochrome in the endogenous regulation of the rhythm.