Beneficial effects of low selenium levels in Lallemantia iberica plants subjected to salinity stress

Selenium (Se) at high concentrations can cause toxic effects in plants, whereas at low concentrations it enhances resistance to certain abiotic stresses. The possible mechanisms of the Se-enhanced tolerance of plants to salinity stress remain elusive. In this work, effect of Se supplementation at 0, 0.1, 1 and 10 mg l-1 sodium selenate was studied in Lallemantia iberica plants subjected to salt stress. In pre-experiment design, The toxicity threshold for selenate was determined at the concentration of 10 mg l-1, as the biomass of L. iberica plants decreased if selenate concentrations in the growth medium reached 10 mg l-1. Thereafter, we used 0.1 mg l-1 Se to mitigate salt stress in L. iberica plants. Se at low concentration (0.1 mg l-1) mitigated salt-induced oxidative stress because of the NaCl-induced lipid peroxidation was smallest in the plants treated with Se, and was highest in the plants grown without Se addition. This occurred as a result of glutathione (GSH) accumulation in Se-supplied plants. Additionally, Se-supplied plants exhibited higher glutathione peroxidase (GSH-Px) activity than –Se ones after 2 days salt stress. These data provided the first evidence that the low-level Se pretreatment alleviated salt stress in L. iberica by increasing GSH levels and by decreasing ROS production; and therefore less reduction of biomass production during salt stress.