Lipoxygenase pathway and membrane permeability and composition during storage of potato tubers (Solanum tuberosum L. cv Bintje and Desiree) in different conditions

Potato tubers (Solarium tuberosum L. cv Bintje and Desiree) were stored for 12 months under three different storage conditions: 4 degreesC, 20 degreesC with sprout inhibitor and 20 degreesC without sprout inhibitor. independent of the storage conditions, our results show that the increase of membrane permeability, as revealed by electrolyte leakage, is not correlated with the lipid saturation status. Moreover, there is no simple correlation between cold sweetening and membrane permeability or lipid saturation status. During storage at 20 degreesC without sprout inhibitor, the increase in membrane permeability is inversely correlated to sucrose accumulation, but this is not the case when tubers were stored with sprout inhibitors. Lipoxygenase (LOX) is often proposed as responsible for peroxidative damage to membrane lipids. The gradual peroxidation resulting in double bond index decrease is regarded as a cause of senescence sweetening. Our results revealed that the role of LOX in aging and senescence of potato tubers is far from clear. LOX activity and gene expression are not correlated with the fatty acids composition of the membrane. Moreover, LOX activity and fatty acid hydroperoxide content are low in older tubers, whatever the storage conditions or the varieties. On the basis of our results, the correlation between sugar accumulation (low temperature and senescence sweetening) and peroxidative damage occurring during storage of potato tubers is discussed.