Regulation of cadmium uptake in the hyperaccumulator Solanum nigrum is mediated by glutathione

Solanum nigrum is a common hyperaccumulator of the heavy metal cadmium (Cd). Our study aims to investigate the impact of glutathione regulation, specifically glutathione overproduction or reduction, on the growth of S. nigrum and its soil remediation potential. To achieve this, plants were subjected to treatments using a glutathione inhibitor (buthionine sulfoximine) and a glutathione promoter (L-2-oxothiazolidine-4-carboxylic acid [OTC]). We assessed plant height, root length and biomass to evaluate the influence of Cd and glutathione regulation on plant growth. Furthermore, we analyzed chlorophyll content. Cd and malondialdehyde (MDA) contents were measured to determine the effect of glutathione regulation on Cd accumulation and lipid peroxidation. Our findings revealed that glutathione overproduction significantly increased the biomass of S. nigrum, resulting in an approximately 12% increase. Additionally, it led to a ca. 10% rise in chlorophylls content. The application of exogenous OTC enhanced reduced glutathione (GSH) content, accompanied by enhanced Cd accumulation. GSH can be converted to oxidized glutathione, which aids in combatting and mitigating Cd toxicity. The MDA content in plants also increased. The overproduction of glutathione holds promise for enhancing heavy metal accumulation and tolerance in hyperaccumulator plants. It provides a theoretical basis for improving hyperaccumulator plants genetically.