MYB-1 regulates anthocyanin biosynthesis in Magnolia wufengensis

Anthocyanin is an essential pigment in all major horticultural crops especially in ornamental trees. Magnolia wufengensis (new species of Magnolia) with red color flower was recently found as a popular species for ornamental use, but anthocyanin synthesis and regulation in M. wufengensis are poorly understood. Herein, transcriptome analysis was used to decipher the gene network associated with anthocyanin biosynthesis. An R2R3-like MwMYB-1 transcription factor was found. MwMYB-1 overexpression resulted in anthocyanin accumulation in tobacco and Arabidopsis. MwMYB-1 worked independently rather than forming a protein complex with bHLH or WD40 protein. According to MwMYB-1 DAP-seq analysis in Arabidopsis, the MwMYB-1 transcription factor preferred to bind the "AAGAGAG" motif (DREME-5) in the third exon of the AtMYB75 gene. The yeast one hybrid assay and transcription activity assay further confirmed this. Thus, MwMYB-1 activated AtMYB75 gene expression and conducted cascade amplification of anthocyanin biosynthesis. Taken together, our findings provide a novel understanding of anthocyanin biosynthesis regulation in M. wufengensis and can be used to promote agronomic trait improvement in tree species.