The roles of starch metabolic pathways in the cold-induced sweetening process in potatoes

Cold-induced sweetening (CIS) is critical for the postharvest quality of potato tubers, and the accumulation of reducing sugar is regulated by several metabolic pathways, such as starch synthesis and degradation, hexogenesis, glycolysis, and anaerobic respiration. Starch is the energy source of storage organs, and its metabolism plays an important role in potato CIS. Here, the processes of starch synthesis and degradation in potato tubers and the functions of related genes in potato CIS are summarized, e.g., adenosine diphosphate glucose pyrophosphorylase, starch synthases, branching enzymes, and debranching enzymes for starch biosynthesis as well as -amylase, -amylase, amylase inhibitors, and starch phosphorylase for starch degradation. Powerful evidence concerning the relevance of genes related to starch degradation and CIS is described. Moreover, future perspectives in starch metabolic research are discussed.