REGULATION OF ANTHOCYANIN SYNTHESIS IN CYMBIDIUM FLOWERS - EFFECTS OF EMASCULATION AND ETHYLENE

Emasculation, by removal of the pollinia and the anther cap, and treatment with ethylene induced red coloration of Cymbidium lips. This coloration was shown to be a result of anthocyanin accumulation that was preceded by a pronounced increase in the activity of phenylalanine ammonia-lyase. Ethylene-induced coloration of isolated lips was inhibited by treatment with 2,5 norbornadiene, cycloheximide and actinomycin-D. The latter, however, was less effective. The results therefore indicate that emasculation and ethylene-induced anthocyanin synthesis is regulated both at the translational and transcriptional levels. The red color of the lip was composed of at least six anthocyanins that were based on three different aglucones, i.e. cyanidin, peonidin and malvidin. Both emasculation and ethylene led to an increase in the total amount of pigment in the lip but had no effect on the relative contribution of the different anthocyanin species. The role of red coloration in pollination biology is discussed. © 1990, Gustav Fischer Verlag, Stuttgart. All rights reserved.