PpMYB10.1 regulates peach fruit starch degradation by activating PpBAM2

Abstract

Starch degradation, a crucial source for soluble sugar, significantly influences fruit flavor development during ripening. Key enzymes in this process include α-amylases (AMYs) and β-amylases (BAMs). In this study, we identified 5 PpAMYs and 9 PpBAMs in peach and categorized them into three and four groups, respectively, based on the gene structures and the phylogenetic analysis. Subsequent expression analysis revealed that elevated levels of PpAMY1, PpAMY5, and PpBAM2 were detected in the middle and late stages of fruit development, suggesting their positive involvement in starch degradation during peach fruit ripening. Transient overexpression experiments conducted in peach fruits and callus further demonstrated that overexpression of PpBAM2 significantly reduced starch content, indicating its important role in starch degradation during peach fruit ripening. Furthermore, we identified a R2R3-MYB transcription factor, PpMYB10.1, which activated the expression of PpBAM2 through the direct interacting with its promoter. In addition, transient overexpression of PpMYB10.1 could significantly reduce starch content in peach callus. Consequently, our findings highlight the positive role of PpBAM2 in peach starch degradation, with PpMYB10.1 serving as an activator during this process.

Keywords: Fruit ripening; MYB; Peach; Starch degradation; Transcriptional regulatory.