Seed Pre-treatment with Polyhydroxy Fullerene Nanoparticles Confer Salt Tolerance in Wheat Through Upregulation of H2O2 Neutralizing Enzymes and Phosphorus Uptake

Polyhydroxy fullerenes nanoparticles (PHF) are regarded as free radical sponges. Can they mitigate oxidative stress and induce tolerance in plants exposed to salinity? The influence of PHF seed pre-treatment on growth and biochemical attributes of NaCl-stressed wheat is studied. Wheat seeds (cv. Ujala) were pre-treated with control, hydro-priming, 10, 40, 80, and 120 nM PHF doses for 10 h and grown in sand-filled pots under control (0 mM NaCl) and salinity (150 mM NaCl) provided through nutrient solution. Salinity markedly decreased root and shoot growth attributes consistent with the reduction in the chlorophyll contents, whereas it increased the antioxidant activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and ascorbate peroxidase (APX) enzymes. Plants exposed to salinity exhibited increase in malondialdehyde (MDA) and hydrogen peroxide (H2O2) contents which indicated oxidative stress. Further, salinity triggered rise in Na+ uptake while decreased in K+ and Ca2+ contents both in the root and shoot. By contrast, wheat seedlings grown from PHF-treated seeds exhibited recovery in root and shoot growth under salinity. This recovery was linked with lower levels of MDA and H2O2 contents and higher antioxidant activities of CAT, POD, and APX enzymes under salinity stress. The PHF-treated plants had higher chlorophyll, free amino acids, ascorbic acid, and soluble sugars. Moreover, PHF seed pre-treatment resulted in higher K+ and P contents in the root while higher P contents in the shoot. Above all, PHF application mitigated adverse effects of salinity and promoted early seedling growth and establishment in wheat.