Selenium reduces cadmium uptake and mitigates cadmium toxicity in rice

Abstract

Hydroponic experiments were performed to investigate physiological mechanisms of selenium (Se) mitigation of Cd toxicity in rice. Exogenous Se markedly reduced Cd concentration in leaves, roots, and stems. Addition or pretreatment of 3μM Se in 50μM Cd solution significantly addressed Cd-induced growth inhibition, recovered root cell viability, and dramatically depressed O2−, H2O2, and malondialdehyde (MDA) accumulation. Supplemental Se counteracted 50μM Cd-induced alterations of certain antioxidant enzymes, and uptake of nutrients, e.g. depressed Cd-induced increase in leaf and root superoxide dismutase (SOD) and leaf peroxidase (POD) activities, but elevated depressed catalase (CAT) activity; decreased Cd-induced high S and Cu concentrations in both leaves and roots. External Se counteracted the pattern of alterations in ATPase activities induced by Cd, e.g. significantly elevated the depressed root H+- and Ca2+-ATPase activities, but decreased the ascent root Na+K+-ATP activity. Results indicate that alleviated Cd toxicity by Se application is related to reduced Cd uptake and ROS accumulation, balanced nutrients, and increased H+- and Ca2+-ATPase activities in rice.