Effects of Foliar Spraying of 2,3-dimercaptosuccinic Acid on Cadmium Uptake, Transport, and Antioxidant System in Rice Seedlings

Abstract

Rice contaminated by Cd has aroused widespread public concern. It is of great importance to find effective ways to reduce Cd translocation from roots to shoots and alleviate Cd stress in rice to ensuring food quality and safety. In this study, 2,3-dimercaptosuccinic acid (DMSA) was sprayed onto the leaves of rice seedlings to evaluate the feasibility of DMSA reducing Cd translocation to rice shoots and alleviating Cd stress. Therefore, seedlings of Zhongzao 35, one of the main rice cultivars in southern China, were used to study the effects of different concentrations of DMSA on the uptake and transport of Cd in rice seedlings by hydroponics. The effects of DMSA on MDA and GSH content, and activities of antioxidant enzymes such as CAT and SOD in rice seedlings, were also investigated. The results showed that after four iterations of foliar application of DMSA at concentrations of 0.2, 0.4, and 1.0 mmol·L-1, the Cd concentration in the rice seedling shoots decreased significantly with increasing DMSA spraying concentration. Compared with the control, the Cd concentration in shoots decreased by 22.1%, 39.7%, and 43.5%, respectively, but had no significant effect on the root Cd concentration. There was no significant effect on the concentrations of K, Ca, Mg, Fe, Zn, or Mn in the shoot or root. The content of MDA and GSH in the shoots of rice seedlings decreased significantly after four spraying times of DMSA and the activity of CAT and SOD increased significantly, which shows that spraying DMSA alleviated the stress effect of Cd on rice seedlings. Foliar application of DMSA can significantly reduce the accumulation of Cd in rice shoots but has no significant effect on the content of six common mineral elements, and can effectively relieve the oxidative damage caused by Cd stress. DMSA has the potential to develop a foliar modulator for reducing rice grain Cd content.