Understanding the dynamics of Cytokinin specific Response Regulators in Anthocyanin biosynthesis in Musa acuminata

RUCHIKA RAJPUT and ASHUTOSH PANDEY

National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi-110067, India

E.mail: ruchikarajput72@gmail.com

Banana is one of the world's most extensively farmed crops and has two significant varieties, i.e., Red banana and Grand Naine, whose most obvious difference is their Peel color. We show that color difference is due to the difference in anthocyanin (AN) accumulation. Using a targeted approach, we performed RNA seq analysis, phytochemical, molecular, genetic and biochemical studies to decipher the transcriptional regulatory network involved in anthocyanin biosynthesis in M. acuminata. We characterized two Cytokinin-specific Response regulators (MaRR1 and MaRR2) and studied their role in anthocyanin biosynthesis in color contrasting varieties. MaRR1 and MaRR2 interacted physically with AN-specific structural gene Dihydroflavonol 4-reductase and bound the promoters of the genes encoding Dihydroflavonol 4-reductase and anthocyanin synthase to transactivated these promoters in vivo. Overexpression of MaRRs in banana fruits resulted in modulation of anthocyanin biosynthesis as well as the accumulation of other interconnected specialised metabolites. Taken together, our results reveal regulatory modules of cytokinin-specific response regulators in contrasting varieties that fine-tune anthocyanin biosynthesis and offer possible targets for genetic manipulation in banana.