Effects of cadmium-added on ascorbate-glutathione cycle of young citrus seedlings under selenite or selenomethionine-enriched soil

摘要

In order to study the effect of cadmium (Cd)-added on citrus growth under selenite or selenomethionine (SeMet)-enriched soil, the concentration of leaf pigments, H 2 O 2 , antioxidants and antioxidases in ascorbate glutathione ( AsA-GSH) cycles were detected in ‘Daya’ citrus seedlings ( Citrus sinensis L.). The results showed that chlorophyll a, b, and a+b were significantly enhanced by cadmium-added under SeMet-enriched treatment, while leaf pigments showed little influence cadmium under selenite-enriched treatment. Meanwhile, cadmium-added significantly increased H 2 O 2 concentration under both selenite and SeMet-enriched soils. In AsA-GSH cycle, the concentration of AsA, dehydroascorbate (DHA), and AsA/(AsA+DHA) ratio were increased, while the levels of GSH, oxidized glutathione (GSSG), and GSH/(GSH+GSSG) were decreased by cadmium-added under selenite or SeMet-enriched soil. Meanwhile, the activities of ascorbate peroxidase (APX), monodehydroascorbate reductase (DHAR), and glutathione reductase (GR) increased, and the activities of glutathione peroxidase (GPX) decreased under selenite or SeMet-enriched soil with cadmium-added. Our results indicated that despite cadmium-added had positive effects on chlorophyll concentrations under Se-enriched soil, leaf was injured by increased H 2 O 2 concentration. Furthermore, the AsA-GSH cycle efficiency was increased to defend cadmium stress under two selenium types-enriched soils.