Interaction between Sulfate and Selenate in Tetraploid Wheat ( Triticum turgidum L.) Genotypes.

Selenium (Se) is an essential micronutrient of fundamental importance to human health and the main Se source is from plant-derived foods. Plants mainly take up Se as selenate (SeO 4 2- ), through the root sulfate transport system, because of their chemical similarity. The aims of this study were (1) to characterize the interaction between Se and S during the root uptake process, by measuring the expression of genes coding for high-affinity sulfate transporters and (2) to explore the possibility of increasing plant capability to take up Se by modulating S availability in the growth medium. We selected different tetraploid wheat genotypes as model plants, including a modern genotype, Svevo ( Triticum turgidum ssp. durum ), and three ancient Khorasan wheats, Kamut, Turanicum 21, and Etrusco ( Triticum turgidum ssp. turanicum) . The plants were cultivated hydroponically for 20 days in the presence of two sulfate levels, adequate (S = 1.2 mM) and limiting (L = 0.06 mM), and three selenate levels (0, 10, 50 μM). Our findings clearly showed the differential expression of genes encoding the two high-affinity transporters ( TdSultr1.1 and TdSultr1.3 ), which are involved in the primary uptake of sulfate from the rhizosphere. Interestingly, Se accumulation in shoots was higher when S was limited in the nutrient solution.