Genome-wide identification of IbGRFs in sweetpotato and functional analysis of IbGRF9 in anthocyanin biosynthesis

Growth-regulating factors (GRFs), a small transcription factor family in plant, hold vital biological roles during developmental processes and plant responses. However, little is known about GRF genes in sweetpotato (Ipomoea batatas L.). Here, 10 IbGRFs were identified and cloned from the sweetpotato genome. Four IbGRF genes contained miR396-binding sites. IbGRF9 had a higher expression level in the transgenic sweetpotato line MIM396. The anthocyanin contents increased in both MIM396 and transgenic Arabidopsis and in the hairy roots of sweetpotato overexpressing IbGRF9. The IbGRF9 protein bound to the promoters of anthocyanin-biosynthesis related genes to increase anthocyanin content. These results raise new insights for the biological function of GRF genes in regulating anthocyanin biosynthesis in sweetpotato.