Abstract To investigate the regulation of flavonoids metabolism in strawberry during ripening, the transcription factor (TF) FaABI3 was isolated and characterized. In strawberry, quercetin, myricetin and quercetin 3-O-glucoside were the major flavonol substances during development, while during ripening, kaempferol and kaempferol 3-O-glucoside accumulated. A positive correlation was observed between the content of quercetin and quercetin 3-O-glucoside and the expression of FaF3’H1 and FaF3’5’H, respectively. Kaempferol and kaempferol 3-O-glucoside contents were positively correlated with FaF3H1, FaF3H2, FaFLS1, and FaF3GT7 expression. Yeast one-hybrid analysis and dual-luciferase assay established FaABI3 as an activator of the promoter of flavonol synthase 1 (FLS1). Analysis of amino acid sequence suggested that FaABI3 belonged to the B3 family. Furthermore, transient silencing of FaABI3 in strawberry down-regulated FaF3’H3, FaFLS1, FaFLS3, FaF3GT3, and FaF3GT7, up-regulated FaF3’5’H, FaF3H2, and FaF3GT6, and regulated the accumulation of flavonoids. In summary, FaFLS1 was transcriptionally regulated by FaABI3, which acted as a regulator of flavonoids metabolism in strawberry.
Lu et al. (Fri,) studied this question.