Selenium and Sulfur Content and Activity of Associated Enzymes in Selected Potato Germplasm

Potato plants are being supplemented with selenium (Se) to enrich tubers with Se for health benefits. Se is not an essential nutrient and interferes with the metabolism of sulfur (S) in plants. The objective of the present investigation was to study the activities of Se-independent glutathione peroxidase (Se-Ind-GPx), Se-dependent glutathione peroxidase (Se-Dep-GPx), and thioredoxin reductase (TRxR) enzymes in stored potato tubers grown on a non-Se-enriched field; and assess their relationship with tuber Se and S levels. The results indicate that these enzyme activities and the Se and S levels in the tubers were significantly influenced by genotype. Se-Dep-GPx activities were influenced by Se levels in the tubers. S content of tubers of all genotypes tested were below the critical nutrition concentration. In spite of this deficiency, the levels of S (which were very high in comparison with Se) influenced the activities of Se-Ind-GPx and TRxR in the tubers. Tubers of some of the genotypes tested can supply more than the recommended dietary allowance (RDA) of Se to adult humans.