The transcription factor AtGLK1 acts upstream of MYBL2 genetically to regulate sucrose-induced anthocyanin biosynthesis in Arabidopsis

【摘要】：The regulation of anthocyanin biosynthesis by various factors including sugars, light and abiotic stresses is mediated by numerous regulatory factors acting at the transcriptional level. Here we provide experimental evidence to show that AtGLK1, the nuclear GARP transcription factor, plays an important role in regulating anthocyanin biosynthesis in Arabidopsis. Real-time quantitative PCR and GUS staining assays demonstrated that AtGLK1 was mainly expressed in the green tissues of Arabidopsis seedlings and could be induced by sucrose. The loss-of-function glk1 glk2 double mutant have lower anthocyanin levels than glk2 single mutant, although loss of AtGLK1 alone does not affect anthocyanin accumulation. Overexpression of AtGLK1 enhances the accumulation of anthocyanin in transgenic Arabidopsis seedlings accompanied by increased expression of anthocyanin biosynthetic and regulatory genes. Moreover, we found that AtGLK1 participates in the plastid-signalling-mediated anthocyanin accumulation. Genetic, physiological and molecular biological approaches demonstrated that AtGLK1 acts upstream of MYBL2, a key negative regulator of anthocyanin biosynthesis, genetically to regulate sucrose-induced anthocyanin biosynthesis. Taken together, these results indicate that AtGLK1 positively regulates sucrose-induced anthocyanin biosynthesis in Arabidopsis via repression of MYBL2.