The Effect of Nitric Oxide on Amaranthus Tricolor L. Under Cadmium Stress

Abstract This study aimed to appraise the crosstalk between sodium nitroprusside (SNP), as a source of nitric oxide (NO), and cadmium (Cd) toxicity on growth and physiological traits in Amaranth tricolor L. by using different multivariate statistical methods. The results showed that growth-related traits of A. tricolor were significantly reduced (p<0.05) under Cd stress. Contrarily, Cd treatments increased lipid peroxidation and reduced total protein content. Delving on the results of SNP application showed the suitability of its medium level (100 µM) on increasing the growth-related traits and also plant tolerance to Cd stress via lowering the lipid peroxidation and radical molecules production due to the higher activities of superoxide dismutase and catalase. Increasing the amount of Cd in roots and shoots, as the results of Cd treatment, reduced the growth and production of A. tricolor plants by high rates (over 50% in 60 mg kg-1 Cd level) indicating its susceptibility to high Cd toxicity. Contrarily, treating plants with NO showed no effect on shoot Cd content, while it significantly increased Cd allocation in the root, which might be attributable to the protective effect of NO on Cd toxicity by trapping Cd in the root. Subsequently, the application of a medium level of SNP (around 100 µM) is recommendable for A. tricolor plant to overcome the negative impacts of Cd toxicity.