Iron oxide (Fe2O3) nanoparticles alleviate PEG-simulated drought stress in grape (Vitis vinifera L.) plants by regulating leaf antioxidants

Iron nanoparticles (Fe NPs) have a wide array of biological and medical applications. In agriculture, Fe NPs has the potential to be used as an innovative technique to alleviate Fe deficiency in various crops, such as grape. However, the effect of Fe NPs on alleviating stresses in grapevine are unexplored. The aim of this study was to evaluate the efficiency of Fe NPs in protecting ‘Asgari’ seedless grape (Vitis vinifera L.) against oxidative stress induced by polyethylene glycol (PEG)-induced drought exposure. Here, we compared six concentrations of Fe NPs to both well-watered and drought-stressed grape plants and evaluated physiological and biochemical parameters in leaves after 30-days of exposure. Our results revealed that physiological indices of plant health such as chlorophyll content, chlorophyll fluorescence (Fv/Fm), and leaf relative water content (RWC) decreased with increased production of H2O2 caused by drought stress. Malondialdehyde (MDA), proline, non-enzymatic [e.g., ascorbate (AsA) and glutathione (GSH)] and enzymatic antioxidants [including monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), catalase (CAT), glutathione peroxidase (GPX), glutathione reductase (GR) and glutathione S-transferase (GST)] exhibited varied responses. Increasing levels of Fe NPs up to 10 µM caused an increase in chlorophyll content and fluorescence under PEG-induced drought stress. Moreover, Fe NPs induced antioxidant protection by reducing MDA and H2O2 generation, and enhancing the concentration of the non-enzymatic antioxidants, such as GSH/ Glutathione disulfide (GSSG) ratio and AsA. Enzymatic activities reported a wide response range, with increases to CAT, GPX, GR, MDHAR and DHAR activities and decreases to GST and ascorbate peroxidase (APX) activities. In conclusion, this study demonstrated that Fe NPs have the potential to be used as an effective method in reducing the negative impact of drought stress in grapevine.