Induction of protein oxidation, protease activity, thiol groups alterations and total antioxidative capacity in potato (Solanum tuberosum) by silver nanoparticles and silver nitrate under in vitro culture conditions

Aim: In the present study, to compare the toxicity and possible oxidative stress that may result from application of silver nanoparticles and silver ions, the impacts of their different concentrations on some biochemical indices related to protein oxidation in potato (Solanum tuberosum) were investigated.
Material and potato explants with one node were transferred to MS medium containing 0, 2, 10 and 20 mg.L-1silver nanoparticles (AgNPs) and silver nitrate (AgNO3). After four weeks of exposure, in vitro-grown explants were harvested for measurement of various parameters.
Total protein content in explants treated with either AgNPs or Ag ions decreased with increase in silver concentration, except in Ag ion treatment at 2 mg.L-1, which it increased significantly as compared to control samples. Also, remarkable changes were observed in five bands of protein electrophoresis patterns. The contents of Carbonyl groups were significantly increased relative to control in a dose-dependent manner. In both silver treatments, protein thiols were significantly decreased, while non-protein thiols were amplified. Moreover, explants treated with Ag ions showed higher protease activity and total antioxidant power as compared to AgNPs treated ones.
Based on the results, it could be concluded that oxidative damage to explants treated with AgNPs was much more than explants under a similar mass of Ag ions. In addition to the release of silver ions, special effects associated with nanoparticles could be involved in the oxidative stress induced by AgNPs in potato explants.