Cadmium-induced oxidative damage in mustard [ Brassica juncea (L.) Czern. & Coss.] plants can be alleviated by salicylic acid

Abstract

The present study was carried out to examine the effects of salicylic acid (SA) on growth, activities of antioxidant enzymes and some physio-biochemical attributes in mustard [ Brassica juncea (L.) Czern. & Coss.] plants exposed to cadmium (Cd) stress. Increasing concentrations of Cd led to decreased growth, shoot biomass, relative water content (RWC) and rate of photosynthesis ( A). SA allayed the adverse effects of Cd on growth, RWC, and A, but the inhibitory effect of Cd on stomatal conductance ( g s) and transpiration rate ( E) was further promoted due to SA treatment. Cadmium-induced oxidative stress increased proline, lipid peroxidation and electrolyte leakage, but on exposure to SA, these parameters showed a marked decrease. Lower concentrations of Cd caused enhanced Cd transport into the plant. Cadmium suppressed the uptake of macro- and micro-nutrients, but exogenous application of SA restored the capability of plants to accumulate essential elements. SA mitigated the Cd-induced inhibition in the growth of mustard plants. Cadmium-induced increase in the activities of some key antioxidant enzymes, superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT), and glutathione reductase (GR) was reduced by the exogenous application of SA. This reflects that SA might have acted as one of the potential antioxidants in mustard plants under Cd stress.