Enzyme activities and gene expression of starch metabolism provide insights into grape berry development

The creation and degradation of carbohydrates such as starch and sugars during grape ripening have important implications for fruit quality. Growers and consumers are increasingly seeking out grapes with greater sugar content, a characteristic which is controlled by the genes and enzymes of starch metabolism. Jinggui Fang of Nanjing Agricultural University, China, and colleagues explored the expression of genes and activity of enzymes causing starch synthesis and breakdown in a red grape cultivar using multiple experimental techniques. They conclude that starch metabolism is a complex, dynamic process, with different genes active in different parts of the grape fruit. Remarkably, changes in starch concentration in fruits were found to be regulated by circadian rhythmns in a similar way to those in leaves. Their findings should help breeders optimise grape varieties for future fruit quality.