Abstract: 【Objective】Two purple-fleshed sweet potato strains ‘A5’, ‘Yamakawamurasaki’ and one white-fleshed sweet potato strain ‘Yubeibai’ were used to study the role of Dihydroflavonol 4-reductase (DFR) in anthocyannin accumulation of purple- fleshed sweet potato. 【Method】Anthocyanin contents, DFR activities and expression of IbDFR gene were determined respectively, while the correlation between the contents of anthocyanin and DFR activities, and that between anthocyanin contents and IbDFR gene expression were analyzed. 【Result】The results show that the activities of DFR are dramatically and positively correlated with the content of anthocyanin no matter in different organs of the same strain or in same organ of the same strain in different growth stages. Moreover, the variation trends of the relative expression of IbDFR gene in storage roots of different strains and of different developing states of ‘Yamakawamurasaki’ also coincided with that of anthocyanin contents in corresponding storage roots. 【Conclusion】 These results indicate that DFR is a key enzyme in anthocyanin synthesis of purple- fleshed sweet potato, and the biosynthesis of anthocyanin is in situ synthesis in purple-fleshed sweet potato.

Key words: Purple-fleshed sweet potato, Anthocyanin, Dihydroflavonol 4-reductase, Correlation analysis