Exogenous ascorbic acid application alleviates cadmium toxicity in seedlings of two wheat (Triticum aestivum L.) varieties by reducing cadmium uptake and enhancing antioxidative capacity.

ABSTRACT

The aggravation of soil cadmium (Cd) pollution is a serious threat to human food health and safety. To reduce Cd uptake and alleviate Cd toxicity in staple food of wheat, a completely random experiment was performed to investigate the effect of exogenous ascorbic acid (AsA) on Cd toxicity in two wheat varieties (L979 and H27). In this study, the treatments with combinations of Cd (0, 5, and 10 µmol L-1) and AsA (0, 50, and 200 µmol L-1) were applied in a hydroponic system. Toxicity induced by Cd inhibited biomass accumulation; decreased wheat growth, photosynthesis, and chlorophyll content; increased lipid peroxidation; and reduced activity of superoxide dismutase (SOD), but stimulated catalase (CAT) and peroxidase (POD). The addition of AsA significantly improved the growth status by increasing the wheat biomass, chlorophyll content, photosynthetic rate, protein concentrations, and antioxidant enzyme activity. Besides, AsA significantly decreased Cd concentration of shoot and root by 14.1-53.9% and 20.8-59.5% in L979 and 23.7-58.8% and 22.1-58.1% in H27 under Cd5, and 23.7-53.6% and 16.6-57.1% in L979 and 21.5-51.6% and 15.3-54.0% in H27 under Cd10, respectively. Malondialdehyde (MDA) accumulation was decreased remarkably with the addition of AsA by 31.2-32.9% in L979 and 27.1-45.2% in H27 under Cd10, respectively. Overall, exogenous application of AsA alleviated the Cd toxicity in wheat plants by improving the wheat growth, soluble protein content, photosynthesis, and antioxidant defense systems, and decreasing MDA accumulation.