Tandem transcription factors PpNAC56 and PpNAC72 synergistically activate the transcription of PpPGF to regulate softening during peach fruit ripening

Abstract

Abstract Rapid softening after harvest is a significant challenge for peach production, as it results in fruit rotting and significantly reduces shelf life. In this study, we conducted an analysis that revealed the presence of two tandem genes, PpNAC56 and PpNAC72, within the sr(slow ripening) locus, which are highly conserved in dicots. Additionally, we found that PpNAC56 is the orthologous gene of Non-ripening (NOR) in tomato. Transcript analysis demonstrated that both PpNAC56 and PpNAC72 are highly expressed in peach fruit, with their transcript levels up-regulated at the onset of peach fruit ripening. The yeast two-hybrid and bimolecular fluorescence complementation assays showed PpNAC56 interacts with PpNAC72 and this interaction is also detected in tomato and apple. Transient VIGS experiments showed that PpNAC56 and PpNAC72 positively regulate peach fruit softening. The Yeast one-hybrid, the dual luciferase assay and LUC bioluminescence imaging proved that PpNAC56 and PpNAC72 directly binds to the PpPGF promoters and activate its transcription. Notably, PpNAC56 and PpNAC72 together, have a higher levels of activation activity for PpPGF than the genes of PpNAC56 or PpNAC72 alone. In summary, our findings demonstrate that the tandem transcription factors PpNAC56 and PpNAC72 synergistically activate the transcription of PpPGF to regulate fruit softening during peach fruit ripening.