Nitrogen and phosphorus co-starvation inhibits anthocyanin synthesis in the callus of grape berry skin

Key message Even though nitrogen and phosphorus deficiencies have been reported to promote anthocyanin biosynthesis in grapevine berries, whether the same deficiencies also induce anthocyanin accumulation in grape callus and whether nitrogen and phosphorus co-deficiency enhances this induction have yet to be reported. Therefore, the present study to investigate the effects of nitrogen starvation, phosphorus starvation, and nitrogen and phosphorus co-starvation on anthocyanin accumulation and ABA signaling in grape callus. Anthocyanins are a type of natural pigment that have high potential for development and utilization in regions like food, pharmaceutical, and cosmetic industries, with nitrogen and phosphorus starvation possibly promoting their accumulation in grapes. However, it remains unclear whether such starvation impacts the grape callus, or how the co-starvation of nitrogen and phosphorus affects the biosynthesis of anthocyanins. Here, we investigated how nitrogen starvation, phosphorus starvation, and the co-starvation of these two elements affects the synthesis of anthocyanins in the callus of grape skin. Results showed that separate starvation of nitrogen and phosphorus, as well as nitrogen and phosphorus co-starvation, inhibited callus growth, while significantly promoting the accumulation of anthocyanins. However, co-starvation did not facilitate anthocyanin biosynthesis during the later stages of callus growth. qRT-PCR analysis showed that the expression ofVvUFGTandVvMYBA1was closely related to anthocyanin accumulation in the callus under nitrogen and phosphorus starvation. Besides, we also confirmed that the abscisic acid signaling pathway was involved in anthocyanin accumulation as well as callus resistance under adverse conditions. This study provides a basis for investigating the regulatory mechanisms of anthocyanin synthesis in grapes, as well as theoretical support for the production of anthocyanins by callus culture.