Selenoamino Acid-Enriched Green Pea as a Value-Added Plant Protein Source for Humans and Livestock

Selenium deficiency in various degrees affects around 15% of the world's population, contributing to a variety of health problems. In this study, we examined the accumulation and biotransformation of soil applied Se-supplementation (sodium selenite and sodium selenate forms) at different concentrations, along with growth and yield formation of green pea, in a greenhouse experiment. Biotransformation of inorganic Se was evaluated using HPLC-ICP-MS for Se-species separation in the above ground parts of green pea. Results showed 3 mg kg^-1 Se^IV increased green pea growth biomarkers and also caused an increase in protein content in leaves by 17%. Selenomethionine represented 65% of the total selenium content in shoots, but was lower in pods and seeds (54 and 38%, respectively). Selenomethionine was the major species in all plant parts and the only organic selenium form in the lower Se^IV concentration range. Elevating the dose of Se^IV (≥30 mg kg^-1) triggered detrimental effects on growth and protein content and caused higher accumulation of inorganic Se in forms of Se^VI and Se^IV. Selenocysteine, another organic form of proteinogenic amino acid, was determined when Se^IV (≥10 mg kg^-1) was applied in higher concentrations. Thus, agronomic biofortification using the appropriate chemical form and concentration of Se will have positive effects on green pea growth and its enriched shoots and seeds provide a value-added protein source for livestock and humans with significant increased selenomethionine.