Iminodisuccinic Acid Relieved Cadmium Stress in Rapeseed Leaf by Affecting Cadmium Distribution and Cadmium Chelation With Pectin

Abstract

Rapeseed (Brassica napus. L) is a nutritious vegetable, while cadmium (Cd) pollution threatens the growth, productivity, and food security of rapeseed. By studying the effects of iminodisuccinic acid (IDS), an easily biodegradable and environmental friendly chelating agent, on Cd distribution at the organ and cellular level, we found IDS promoted dry matter accumulation of rapeseed and increased the contents of photosynthetic pigment in leaves. Inhibited root-shoot Cd transport resulted in higher activity of antioxidant enzymes and decreased hydrogen peroxide (H2O2) and malondialdehyde (MDA) accumulation in leaves, which indicated that IDS contributed to alleviating Cd-caused oxidative damage in leaf cells. Additionally, IDS increased Cd distribution in cell wall (CW) and relieved Cd toxicity in organelle of leaves, while IDS did not change the contents of different CW components. The improved Cd fixation in leaf CW was mainly attributed to enhanced demethylation of covalently bound pectin (CSP) and Cd chelation with CSP.