Physiological and Molecular Effects of Silver Nanoparticles Exposure on Purslane (Portulaca oleracea L.)

Due to the antifungal and antibacterial properties, silver nanoparticles (AgNPs) are now widely used in consumer products. In this research, the effects of various concentrations of AgNPs (0, 2.5, 5, 10, 20, 40 and 80 ppm) on growth, contents of micro- and macroelements, physiological traits and expression of PAL and GSH genes of purslane (Portulaca oleracea L.) plants were investigated. The results showed that application of AgNPs resulted in a dose-dependent enhancement in accumulation of silver (Ag) in both root and leaf tissues, however, the Ag accumulated at the root more than the leaf at all levels of the AgNPs treatment. AgNPs treatment over 20 ppm reduced the growth, biomass production and accumulation of macroelements (Ca and Mg) and microelements (Zn, Cu, Mn and B) and increased contents of H2O2, MDA and DPPH scavenging activity. Application of AgNPs also increased the activity of antioxidant enzymes such as SOD, CAT and POD enzymes compared to control treatments. The activity and expression of PAL and CHS enzymes significantly increased under treatment of AgNPs. Our results indicate that increasing the activity of antioxidant enzymes and regulating the expression and activity of PAL and CHS enzymes are mechanisms to counteract the oxidative stress induced by AgNPs in the purslane plants.