Analysis of rabbiteye blueberry metabolomes and transcriptomes reveals mechanisms underlying potassium-induced anthocyanin production

Environmental factors play an important role in anthocyanin biosynthesis, and potassium, an essential nutrient for blueberry growth, can act as an enzyme activator. However, few reports exist on the transcriptional and anthocyanin metabolic changes in blueberries regulated by potassium. The results indicated that potassium treatment significantly increased the contents of malvidin, petunidin, and delphinidin in blueberry fruits and accelerated early color development, particularly favoring the accumulation of darker pigments such as malvidin, petunidin, and delphinidin when applied at the young fruit stage. Transcriptome analysis identified 102 glucose metabolism-related genes and 12 differential potassium transport genes potentially involved in potassium-mediated anthocyanin synthesis and accumulation, with AKT1 and KUP potassium transporters being upregulated under potassium fertilization. In the anthocyanin biosynthesis pathway, 13 genes, including UFGT, F3H, CHI, HCT, C12RT1, DFR, and F3'5'H, were closely linked to flavonoid and anthocyanin metabolite synthesis regulated by potassium. Furthermore, potassium treatment markedly enhanced the activities of key enzymes, F3H, F3'5'H, and UFGT, in the anthocyanin synthesis pathway of blueberry fruits. Overall, these findings elucidate the influence of potassium application timing on anthocyanin synthesis and provide valuable insights into the molecular mechanisms governing anthocyanin biosynthesis in blueberries.