Effects of foliar-sprayed potassium dihydrogen phosphate on accumulation of flavonoids in Cabernet Sauvignon (Vitis vinifera L.)

BACKGROUNDIn current vineyards, potassium dihydrogen phosphate (KH2PO4) is a common foliar fertilizer with the lowest salt index. It is employed to improve the transportation and distribution of grape photosynthetic products, but the mechanism of its effect on fruit flavonoid synthesis is unclear. RESULTSThis study investigated the effects of foliar spraying of KH2PO4 at different developmental stages (1 week before veraison; the end of veraison (EV)) on flavonoid metabolites and related gene expression of 'Cabernet Sauvignon' grape for two consecutive vintages. High-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry technology was used to identify 6 flavan-3-ols, 11 flavonols, and 16 anthocyanins. KH2PO4 influenced anthocyanins content, especially when applied at the EV stage, the content of anthocyanins was significantly higher than that of the control. Further, quantitative polymerase chain reaction analysis showed that KH2PO4 treatment applied at the EV stage can increase the expression of anthocyanin synthesis genes and accelerate anthocyanin synthesis. In particular, the expression of VviGST in EV treatment was significantly higher than that of the control during the development process. CONCLUSIONThese findings have enhanced our understanding of the effect of KH2PO4 treatment on grape flavonoids. Among them, EV treatment can significantly increase anthocyanins content. (c) 2023 Society of Chemical Industry.