A PbrNAC14 activated PbrMYBL4/PbrSGR2 repressor modulates pigment homeostasis in pear fruit pericarp

Abstract

Abstract The concurrent processes of anthocyanin accumulation and chlorophyll degradation are pivotal to fruit color development and quality attainment during ripening. However, the regulatory mechanisms that coordinate their dynamic equilibrium within the fruit pericarp remain poorly understood. In this study, we identified the NAC transcription factor PbrNAC14 as a key regulator by examining the distinctive red-to-yellow-green transition zone of 'Red Zaosu' pear pericarp. Our results demonstrated that PbrNAC14 could repress anthocyanin biosynthesis by activating the transcriptional repressor PbrMYBL4 via direct binding to the TTTCGTGT and TTTCGT cis-elements within the PbrMYBL4 promoter. Concurrently, PbrNAC14 modulated chlorophyll degradation by binding to the ACGAAA and CGTG elements in the promoter of the chlorophyll catabolism gene PbrSGR2. In summary, our data establish that PbrNAC14 directly activates PbrMYBL4 and PbrSGR2, which act as repressors of anthocyanin and chlorophyll turnover, respectively, thereby fine-tuning pericarp pigmentation during pear fruit ripening. These findings uncover a previously unknown regulatory network and identify potential genetic targets for precision breeding programs to enhance fruit quality.