An ETHYLENE RESPONSE FACTOR-MYB Transcription Complex Regulates Furaneol Biosynthesis by Activating Expression in Strawberry.

4-Hydroxy-2,5-dimethyl-3(2H)-furanone is a major contributor to the aroma of strawberry ( × ) fruit, and the last step in its biosynthesis is catalyzed by strawberry quinone oxidoreductase (FaQR). Here, an ethylene response factor (FaERF#9) was characterized as a positive regulator of the promoter. Linear regression analysis indicated that transcript levels were correlated significantly with both transcripts and furanone content in different strawberry cultivars. Transient overexpression of in strawberry fruit significantly increased expression and furaneol production. Yeast one-hybrid assays, however, indicated that FaERF#9 by itself did not bind to the promoter. An MYB transcription factor (FaMYB98) identified in yeast one-hybrid screening of the strawberry cDNA library was capable of both binding to the promoter and activating the transcription of by ∼5.6-fold. Yeast two-hybrid assay and bimolecular fluorescence complementation confirmed a direct protein-protein interaction between FaERF#9 and FaMYB98, and in combination, they activated the promoter 14-fold in transactivation assays. These results indicate that an ERF-MYB complex containing FaERF#9 and FaMYB98 activates the promoter and up-regulates 4-hydroxy-2,5-dimethyl-3(2H)-furanone biosynthesis in strawberry.