Silicon nanoparticles (SiNPs) mediate GABA, SOD and ASA-GSH cycle to improve Cd stress tolerance in Solanum lycopersicum

Contamination of agricultural products with Cadmium (Cd) is a global problem that should be considered for minimizing the risks to human health. Considering the potential effects of SiNPs in decreasing abiotic stress, a study was conducted to investigate the effect of SiNPs in the reduction of Cd stress on Solanum lycopersicum. SiNPs was used at 0, 25, 50 and 100 mg/l and CdCl₂ at 0, 100 and 200 µM concentrations. The results showed that Cd stress caused a significant decrease in dry weight, content of GSH, ASA, significently increasing the activity of GR, APX, GST, SOD, as well as content of H₂O₂, MDA, proline, and GABA in shoots and roots compared to the control. SiNPs significantly increased shoot and root dry weight compared to the control. As a coenzyme, SiNPs induced the activity of antioxidant enzymes and significantly increased GST and GR gene expression compared to the control. SiNPs also caused a substantial increase in the content of ASA, GSH, proline and GABA compared to the control. By inducing the activity of antioxidant enzymes and metabolites of the ascorbate-glutathione (ASA-GSH) cycle, SiNPs removed a large content of H₂O₂ and significantly reduced the MDA content, and as a result led to the stability of cell membrane under Cd stress. Induction of ASA-GSH, GABA and SOD cycle by SiNPs clearly showed that SiNPs could be a potential tool to alleviate Cd stress in plants cultivated in areas contaminated with this heavy metal.