NAC Transcription Factor PpNAP4 Promotes Chlorophyll Degradation and Anthocyanin Synthesis in the Skin of Peach Fruit

Chlorophyll (Chl) catabolism and anthocyanin synthesis play pivotal roles in determining the final skin color of fruits during maturation. However, in peach (<i>Prunus persica</i>) fruit, the regulatory mechanism governing skin color, especially the Chl catabolism, remains largely elusive. In this study, we identified ten Chl catabolic genes (CCGs), with <i>PpSGR</i> emerging as a key regulator in Chl degradation in peaches. Furthermore, a NAC-like, activated by AP3/P1 (NAP) transcription factor (TF), PpNAP4, was identified as a positive modulator of Chl breakdown. PpNAP4 induced the expression of <i>PpSGR</i> and other CCGs, including <i>PpPPH</i>, <i>PpPAO</i>, and <i>PpTIC55-2</i>, by directly binding to their promoters. Overexpression of <i>PpNAP4</i> resulted in a heightened expression of these genes and accelerated Chl degradation. Notably, PpNAP4 also positively regulated the expression of <i>PpANS</i> and <i>PpMYB10.1</i>, one key structural gene and a core transcriptional regulator of anthocyanin synthesis, thereby contributing to fruit coloration. In summary, our findings elucidate that PpNAP4 serves as a pivotal regulator in determining the final skin color of peach by orchestrating Chl degradation and anthocyanin accumulation through direct activation of multiple CCGs and anthocyanin related genes.