LOW-TEMPERATURE ENHANCES PETUNIA FLOWER PIGMENTATION AND INDUCES CHALCONE SYNTHASE GENE-EXPRESSION

Flower coloration is controlled by internal and external factors, incl uding temperature. The aim of the present work was to examine the effe ct of temperature on anthocyanin synthesis and chalcone synthase gene (chs) expression in petunia flowers. A moderate-low temperature enhanc ed both anthocyanin accumulation and chs expression in the corollas. H owever, the effect on chs expression was not always correlated with th at on anthocyanin content, suggesting a post-translational effect. The effect was local and required the exposure of corollas, but not the w hole plant, to the ambient temperature. The response of chs to moderat e-low temperatures did not coincide with its expression during flower development. Moderate-low temperatures only slightly affected gibberel lic acid (GA(3))-induced chs expression in the light, but activated ch s expression under non-inducing conditions, i.e. in the absence of GA, in the dark. The results of this study suggest that moderate-low temp eratures do not simply enhance the developmental regulation of anthocy anin biosynthetic gene expression; they act as a specific and separate signal.