The PEPCK and FBP Genes Regulate Gluconeogenesis Metabolism in Grape Berries in Response to Light Intensity

Sugar–acid metabolism is a key factor in determining grape quality, and gluconeogenesis is one of the important sugar–acid metabolic pathways. To explore the effects of reduced light intensity on grape berry quality and gluconeogenesis under greenhouse cultivation, we used the ‘Shine Muscat’ cultivar. With decreasing light intensity, the photosynthetic activity in the grape leaves decreased, resulting in significant reductions in the net photosynthetic rate, transpiration intensity, and stomatal conductance while reducing organic matter accumulation, thus significantly affecting subsequent grape berry quality and gluconeogenesis. Shade treatment inhibited the accumulation of glucose, fructose, and soluble solids in the grape berries but promoted the accumulation of malic acid, tartaric acid, and citric acid. PEPCK and FBP are the key genes underlying the effect of light intensity on gluconeogenesis in grape berries, with PEPCK being involved mainly in tartaric acid metabolism and FBP being involved in malic acid, citric acid, and tartaric acid metabolism.