Abstract
The objective of this study was to explore the effect of seed nanopriming with ZnONPs on the biomass accumulation, nutrient elements content, activity and gene expression of enzymatic antioxidants in shoots and roots of wheat plant. Maximum promontory response with respect to shoot and root biomarkers was shown in lower ZnONPs level (100 mg L-1), meanwhile at higher concentration (800 mg L-1) there was a marked suppression of growth biomarkers. Nanopriming with lower ZnONPs concentrations insignificantly changed the elements content in the shoots and roots and their transportation factors (TF). Conversely, the elements content and their transportation from root to shoot under higher ZnONPs treatments were significantly decreased compared to the untreated control. Zn content in the shoots and roots was markedly increased in a concentration – dependent trend. Seed nanopriming enhanced the activity of SOD, CAT and APx in the shoots and roots, however CAT and APx activities in the roots were markedly decreased at higher ZnONPs levels but the attained values were significantly higher than the control. The expression of SOD, CAT and APx genes was markedly up regulated in response to nanopriming with ZnONPs. This expression showed different response according to the ZnONPs concentrations and plant organs. The results suggest that the ZnONPs stimulatory and phytotoxicity effects may be attributed to the concentration of released Zn ions from ZnONPs in the plant tissues.

Key words: Enzymatic antioxidants-gene expression-priming-wheat-ZnO nanoparticles