A mechanism for low temperature induced sugar accumulation in stored potato tubers: The potential role of the alternative pathway and invertase

Abstract

The accumulation of reducing sugars in stored potato tubers is of significant commercial importance because of its effect on processing quality. The process by which the accumulation of sugars occurs involves the interaction of many metabolic pathways and is yet to be fully described. Low temperature conditions result in an accumulation of ATP in potato tissue. Published evidence suggests that low temperature activation of the alternative pathway (cyanide resistant respiration) leads to decreased ATP levels and simultaneous increases in sucrose concentrations. This sucrose becomes the substrate for vacuolar acid invertase resulting in the accumulation of reducing sugars. Inhibition of the alternative pathway results in decreased sugar accumulation thereby minimizing the sucrose available to the acid invertase and the subsequent reducing sugar accumulation. Control of the alternative pathway on its own, or in combination with acid invertase activity, may provide insight into the phenomenon of low temperature sweetening in stored potato tubers.