The PavPIF3/PavMYC2-PavMYB75L/PavCOP1 regulatory module integrates light and jasmonic acid signaling to regulate...

Light induces blush sweet cherry fruit coloration. We determined that the phytohormone jasmonic acid (JA) is important for fruit coloration under light conditions. However, the genes and molecular mechanisms underlying the integrated regulatory effects of light and JA signaling pathways on anthocyanin biosynthesis in blush sweet cherry fruits remain unknown. On the basis of whole genome re-sequencing and comparative transcriptome analyses, we identified PavMYB75-like (PavMYB75L) as a candidate gene encoding an R2R3-MYB transcription factor that regulates light-dependent fruit coloration. PavMYB75L overexpression in sweet cherry calli, Nicotiana tabacum, and Fragaria vesca enhanced anthocyanin accumulation and fruit coloration, whereas silencing PavMYB75L in sweet cherry fruits suppressed coloration. PavMYB75L was revealed to bind directly to the promoters of anthocyanin biosynthesis-related genes, leading to increased expression. An E3 ubiquitin ligase PavCOP1 was identified by IP-MS. Notably, PavCOP1 interacts directly with PavMYB75L and ubiquitinates PavMYB75L, targeting it for degradation through the ubiquitin/26S proteasome pathway, ultimately downregulating anthocyanin accumulation in darkness. We observed that PavCOP1 regulates fruit coloration by decreasing PavMYB75L abundance and stability. Light-responsive factor PavHYH and JA-responsive TF PavMYC2, which were identified by yeast one-hybrid screening, interact directly with the PavMYB75L promoter and activate expression, thereby promoting fruit coloration. Furthermore, phytochrome-interacting factor PavPIF3 interacts with PavHYH and PavMYC2 to accelerate the activation of PavMYB75L expression. Thus, PavPIF3/PavMYC2-PavMYB75L/PavCOP1 is a regulatory module that integrates light and JA signaling to promote blush sweet cherry fruit coloration, providing new insights into the molecular basis of anthocyanin accumulation.