Selenium and Sulfur Content and Activity of Associated Enzymes in Selected Potato Germplasm Venu Perla & David G. Holm & Sastry S. Jayanty Published online: 19 January 2012 # Potato Association of America 2012 Abstract Potato plants are being supplemented with sele- nium (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 investi- gation was to study the activities of Se-independent gluta- thione 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 activi- ties and the Se and S levels in the tubers were significantly influenced by genotype. Se-Dep-GPx activities were influ- enced by Se levels in the tubers. S content of tubers of all genotypes tested were below the critical nutrition concen- tration. In spite of this deficiency, the levels of S (which were very high in comparison with Se) influenced the ac- tivities 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. Resumen Las plantas de papa están siendo suplementadas con selenio (Se) para enriquecer los tubérculos con Se para beneficio de la salud. El Se no es un nutrimento esencial e interfiere con el metabolismo del azufre (S) en plantas. El objetivo de la presente investigación fue estudiar las activi- dades de las enzimas glutatión-peroxidasa independiente de Se (Se-Ind-GPx), glutatión-peroxidasa dependiente de Se (Se-Dep-GPx) y thioredoxin reductasa (TRxR) en tubérculos de papa almacenados provenientes de un campo no enriquecido con Se; y analizar su relación con los niveles de Se y S en el tubérculo. Los resultados indican que las actividades de estas enzimas y los niveles de Se y S en tubérculos fueron influenciados significativamente por el genotipo. Las actividades de Se-Dep-GPx se influenciaron por los niveles de Se en los tubérculos. El contenido de S en tubérculos de todos los genotipos probados estuvo debajo de la concentración crítica de nutrición. A pesar de esta defi- ciencia, los niveles de S (que fueron muy altos en compa- ración de Se) influenciaron las actividades de Se-Ind-GPx y TRxR en los tubérculos. Tubérculos de algunos de los genotipos probados pueden surtir mas de lo recomendado para la dieta de Se en humanos adultos. Keywords Solanum tuberosum L. . Glutathione peroxidase . Thioredoxin reductase . Protein Introduction Se is an essential trace element in the human body. Devel- opment and survival of animals and humans will be at risk without Se (Reilly 1996). Adult humans require 55–70 μg of Se per day in their diet (McDowell 2003). Adequate levels of Se in blood plasma have been correlated with reducing pancreatic, gastric, lung, nasopharyngeal, breast, uterine, respiratory, digestive, hematological, and gyneco- logical cancers; several cardiovascular diseases, such as myocardial infarction, atherosclerosis, congestive heart fail- ure, cardiomyopathy, arterial hypertension, chronic heart disease, and coronary atherosclerosis (Navarro-Alarcon and Lopez-Martinez 2000); muscle disorders such as pain, tenderness, weakness, and wasting (Chariot and Bignani 2003); hepatopathy, cirrhosis; and to a certain extent V. Perla : D. G. Holm : S. S. Jayanty (*) San Luis Valley Research Center, Department of Horticulture and Landscape Architecture, Colorado State University, 0249 East County Road 9N, Center, CO 81125, USA e-mail: sastry.jayanty@colostate.edu Am. J. Pot Res (2012) 89:111–120 DOI 10.1007/s12230-011-9232-1