Phase‐shifting effects of indole‐3‐acetic acid and the synchronization of three circadian metabolic rhythms inAcetabularia

Abstract

Rhythms of photosynthesis and of polysacchande and fatty acid contents were measured simultaneously in Acetabularia mediterranea in constant light, 3 mW.m². They had the same free‐running period of 24.7 ± 0.8 h, the peak of photosynthesis being detected 3 h before the peak of the polysaccharide content and the main peak of the fatty acid content. The auxin indole‐3‐acetic acid, 100 μ M, was introduced into the medium at CT 12, the end of the subjective light phase. It induced the same phase advances or delays of photosynthesis and polysacchande content rhythms; it always provoked phase advance of the fatty acid content rhythm.