Selenium Species in Selenium-Enriched and Drought-Exposed Potatoes

摘要

The aim of this work was to study selenium(Se)speciation in the potato(Solanum tuberosum L.)cultivar Desiree,enriched in Se by foliar spraying with a water solution containing 10 mg of Se/L in the form of sodium selenate.Four combinations of treatments were used:well-watered plants with and without Se foliar spraying and drought-exposed plants with and without Se foliar spraying.Water-soluble Se compounds were extracted from potato tubers by water or enzymatic hydrolysis with the enzyme protease XIV,amylase,or a combination of protease XIV and amylase.Extraction was performed using incubation at a constant temperature and stirring(37°C at 200 rpm)or by ultrasound-assisted extraction(300 W),using different extraction times.Separation of soluble Se species(SeCys2,SeMet,SeMeSeGys,selenite,and selenate)was achieved by ion-exchange chromatography,and detection was performed by inductively coupled plasma-mass spectrometry(ICP-MS).Results showed that the concentration of selenate extracted was independent of the enzymatic extraction technique(approximately 98 ng/g for drought-exposed and 308 ng/g for well-watered potato tubers),whereas the extraction yield of SeMet changed with the protocol used(10-36%).Selenate and SeMet were the main soluble Se species(representing 51-68% of total Se)in potato tubers,regardless of the growth conditions.