Interactive effects of cytokinins, light, and sucrose on the phenotypes and the syntheses of anthocyanins and lignins in cytokinin overproducing transgenic Arabidopsis

Elevated cytokinins levels in vivo resulted in both enlarged and retarded growth phenotypes. Cytokinin levels were similar in both phenotypic groups. The ratio of the two phenotypes could be altered by changing the sucrose concentration in MS medium or the light intensity. Increased cytokinins in ipt:: GUS activated Arabidopsis induced the syntheses of anthocyanins and lignins, while light speeded up the anthocyanin accumulation. The endogenous increase in cytokinins and exogenous addition of sucrose in MS medium caused similar effects on the formation of anthocyanins and lignins in shoot, especially in the shoot apical meristem. Cytokinins induced CHS transcription in ipt:::GUS-activated Arabidopsis seedlings in the vegetative growth period; the transcription of CHS was low in ipt inactive plants and in wild-type Columbia. Cytokinins were capable of influencing either the synthesis or distribution of chlorophylls, but they did not alter cab and rbcS transcriptions in light-grown seedlings.