The DOF transcription factor, FaDOF1 affects eugenol accumulation in strawberry

Eugenol is one of the most important phenylpropanoid volatiles in strawberry fruit. The DOF (DNA binding with One Finger) proteins are plant-specific transcription factors, which are involved in diverse biological processes. However, the molecular mechanism of how the DOF transcription factors regulate eugenol biosynthesis is poorly understood. In this study, the novel DOF transcription factor, Fragaria × ananassa DOF1 (FaDOF1), was identified and characterized. Analysis of subcellular localization using GFP showed that FaDOF1 was localized in the nucleus. FaDOF1 was highly expressed in flowers and peaked at small green fruit stage during maturity. Eugenol concentrations at different developmental stages and tissues had significant correlations with the transcription levels of FaDOF1. Transient overexpression and silencing of FaDOF1 promoted and repressed eugenol accumulation in strawberry fruit, respectively. Y1H, GUS, and dual-LUC assays indicated that FaDOF1 was bound at the promoters of the two key genes in eugenol biosynthesis, FaEGS1 and FaEGS2, and activated their transcripts. In summary, our results suggest that FaDOF1 acts as a positive regulator of eugenol metabolism, which provide new insights into the regulatory mechanisms that can improve the quality of strawberry fruit.