Boron decreased cadmium accumulation in water spinach by enhancing cadmium chelation of covalently bound pectin in the root cell wall

Abstract Cadmium (Cd) contamination and boron (B) deficiency are two major challenges associated with the farmland soils in Southern China. Therefore, this study was undertaken to examine the impacts of B supply on Cd accumulation in water spinach ( Ipomoea aquatica ) by using cultivar (T308) with high Cd concentration. The study further investigated the physiological mechanism behind the changes in Cd accumulation due to B supply. The findings revealed that B supply substantially reduced the Cd concentration in the leaves of water spinach by 41.20% and 37.16% under the Cd stress of 10 µM and 25 µM, respectively. Subcellular distribution of Cd showed that the Cd content as well as its proportion in root cell wall (RCW) increased significantly after B supply. Fourier transform infrared spectroscopy showed a significant enrichment of negative charged groups (such as -OH, -COOH, and -NH 2 ) in the RCW after B supply. Overall, B supply also enhanced covalently bound pectin (CSP) content as well as the Cd content linked with CSP under Cd stress. These observations revealed that B regulated the Cd chelation in RCW, thereby reducing the amassment of Cd in water spinach.