Influence Of Brassinosteroid On Cytokinin-induced Anthocyanin Accumulation In Arabidopsis Seedlings

Brassinosteroids(BRs). a class of steroidal plant hormones, play important roles in plant growth and development. Cytokinins have been shown to induce anthocyanin accumulation in Arabidopsis. In order to investigate the influences of BR on cytokinin-induced anthocyanin accumulation in Arabidopsis seedlings, physiological and molecular approaches were used to reveal the mechanism of BR affects cytokinin-regulated anthocyanin pigmentation in Arabidopsis. The results were as follows:BR positively regulates cytokinin-induced anthocyanin accumulation in Arabidopsis seedlings. Anthocyanin accumulation induced by cytokinin was reduced in BR-biosynthetic mutants dwf4-102, pscl (a leaky mutant in DWF4), and BR-perceiving mutant bril-4. whereas was promoted by an application of exogenous BR in wild type.BR affects cytokinin-induced anthocyanin accumulation by regulating the "late" anthocyanin biosynthesis genes. The expression of the "late" anthocyanin biosynthesis genes DFR. LDOX. and UF3GT induced by cytokinin were reduced in BR-biosynthetic mutant dwf4-102. pscl,and BR-perceiving mutant bril-4. yet were increased by an application of exogenous BR in wild type.The expression of the "early'anthocyanin biosynthesis genes PAL1, CHS, and CHI induced by cytokinin were increased in the BR-biosynthetic mutant dwf4-102.The expression of the'early'anthocyanin biosynthesis genes PAL1, CHS, and CHI were increased in the bril-4mutant, and reduced the sensitivity to the inductive effect by cytokinin.