Cadmium Tolerance Mechanism of Solanum nigrum Based on Subcellular Distribution and Organic Acid Content

Solanum nigrum (S. nigrum), a newly discovered Cd-hyperaccumulator, has attracted the attention of many scholars. The present experiment was aimed to explore the difference of Cd accumulation ability among different S. nigrum genotypes and reveal the underlying mechanism. Three different genotypes of S. nigrum were grown in a hydroponic system with different Cd levels (0, 10,25, 50, 100 mg L-1, respectively); the Cd content, subcellular distribution of Cd, net Cd fluxes of in S. nigrum roots, and organic acid content in S. nigrum leaves were investigated. The results showed that Cd was more abundant in cell sap and cell wall fraction than that in organelle fraction. The content of organic acids in three species of S. nigrum was citric acid > tartaric acid > acetic acid > malic acid > oxalic acid. Non-destructive micrometry (NMT) revealed that the net Cd fluxes of the same species of S. nigrum first increased and then decreased with increasing of Cd concentration. And among all tested genotypes, the net Cd fluxes were stronger in the genotype of S. nigrum (HZ).

Automated summary

This study explored the difference in cadmium accumulation ability among different genotypes of Solanum nigrum and revealed the underlying mechanism. The results showed that cadmium was more abundant in cell sap and cell wall fraction, and the content of organic acids in S. nigrum leaves followed the order citric acid > tartaric acid > acetic acid > malic acid > oxalic acid. Non-destructive micrometry revealed that the net cadmium fluxes first increased and then decreased with increasing cadmium concentration, and S. nigrum genotype (HZ) had the strongest net cadmium fluxes.