PpSnRK1α-PpNAC6/PpNAC36 module mediates nitrogen-regulated biosynthesis of γ-decalactone in peach fruit

Flavor-related compounds, particularly γ-decalactone—the key contributor to the characteristic ‘peach-like’ aroma—serve as essential indicators of peach fruit quality and strongly influence consumer purchasing decisions. However, excessive application of N fertilizers has led to a significant decline in the flavor quality of peaches, posing a major obstacle to the sustainable development of the peach industry. Although this remains a critical challenge, the molecular mechanisms linking N to flavor compound biosynthesis are still not well characterized. In this study, we discovered that excessive N application reduced the biosynthesis of γ-decalactone in peach, based on multi-year field observations. Correlation analysis and expression profiling under N treatments revealed that two NAC (NAM-ATAF1/2-CUC2) transcription factors (TFs), PpNAC6 and PpNAC36, were involved in regulating γ-decalactone biosynthesis in response to N signaling. Genetic analyses indicated that PpNAC6 and PpNAC36 positively regulated the accumulation of γ-decalactone. Both yeast one-hybrid (Y1H) assays and dual-luciferase reporter assays consistently showed that PpNAC6 and PpNAC36 directly interact with the promoter regions of γ-decalactone biosynthesis-related genes (PpAAT2, PpAAT3, PpLOX1, PpLOX6, and PpFAD3) and significantly enhance their transcriptional activity. Furthermore, transgene verification demonstrated that the α subunit of peach SNF-related Kinase 1 (PpSnRK1α) suppresses γ-decalactone biosynthesis. Notably, we found that PpSnRK1α interacts with PpNAC6/PpNAC36 and selectively phosphorylates PpNAC36 in response to N, thus regulating γ-decalactone production. Our study uncovers the transcriptional regulatory network involved in PpSnRK1α-mediated phosphorylation of PpNAC6/PpNAC36, linking N signaling to γ-decalactone synthesis in peach, and provides insights for molecular breeding and precision fertilization to enhance peach flavor.