DIFFERENCES IN SELENIUM UPTAKE AND TRANSPORT, AND RELATED GENE EXPRESSION IN THREE BRASSICA VEGETABLES

Selenium (Se) is an essential micronutrient for humans, animals and plant growth. The consumption of plant products containing a high Se concentration, is the most efficient and safe way of Se supplementation. Selenium concentrations in plants vary depending on exogenous selenium levels, plant species and variety. In the recent pot experiment, the effects of exogenous selenium (0, 0.5, 1.0, 2.5 and 5 mg.kg(-1)) on the selenium uptake and transport of three Brassica vegetables (Brassica rapa ssp. chinensis L., Brassica rapa ssp. pekinensis L. and Brassica oleracea var. capitata L.) were studied. The expression levels of selenium metabolism related genes families, such as APS, APR, SAT, SMT, CysD and MMT, were also detected using qRT-PCR assays. The results showed that selenium concentration in leaves, stems and roots of the three Brassica vegetables increased with the increase of soil selenium level. The selenium concentration in the leaves of the three Brassica vegetables was the highest at selenium level of 5 mg.kg(-1) . Leaf selenium concentration of Brassica rapa ssp. chinensis L. was significantly 1.39-3.02 times higher than that of the other two vegetables. Under the same selenium treatment, selenium concentration, selenium accumulation coefficient and transport coefficient of edible parts of Brassica vegetables were the highest in Brassica rapa ssp. chinensis L. and the lowest in Brassica oleracea var. capitata L. At soil selenium level of 5 mg.kg(-1), the expression levels of SAT, SMT and MMT in leaves of Brassica rapa ssp. chinensis L. and the expression levels of SAT, APS, SMT, APR and MMT in leaves of Brassica pekinensis L. significantly increased. Brassica rapa ssp. chinensis L. had the best selenium enrichment effect among the three Brassica vegetables.