Zinc nanoparticles alleviate vanadium stress in wheat (Triticum aestivum L.): Impacts on vanadium accumulation, nitrogen assimilation, and amino acid profile

Zinc oxide nanoparticles (ZnO-NPs) have been suggested as a means to alleviate the toxicity of vanadium (V) in plants; however, the impact on V accumulation and grain nutritional quality remains to be elucidated. In light of this, a comprehensive life cycle study was conducted to examine the effects of ZnO-NPs on wheat growth, V transport and accumulation, nitrogen assimilation enzymes, and amino acid profiles of wheat seeds in a pot experiment. Results indicated that V stress adversely affected growth by increasing V accumulation and reducing the nutritional quality of wheat seeds. ZnO-NPs significantly reduced V uptake and bioaccumulation, while enhancing the yield and quality of wheat seeds. Under V stress, ZnO-NPs increased chlorophyll content, photosynthesis, and phytohormone levels (IAA, CTK, GA, and BRs) in flag leaves during the grain-filling stage. Additionally, ZnO-NPs elevated the total nitrogen content of wheat seeds by activating the key nitrogen assimilation enzymes, such as glutamine synthetase, glutamate synthase, and glutamate dehydrogenase, in both flag leaves and seeds during the grain-filling stage. ZnO-NPs also significantly increased levels of essential amino acids like valine, isoleucine, leucine, phenylalanine, histidine, and lysine in wheat seeds at maturity under V stress. The study suggested that applying ZnO-NPs to wheat in V-contaminated soils could enhance growth, yield, and nutritional quality while concomitantly reducing the V concentration in plants.