Ameliorative Effects of Zinc Oxide Nanoparticles Against Heat Stress in Wheat (Triticum Aestivum L.)

Abstract

Wheat, a fundamental global food crop, is increasingly susceptible to heat stress due to the challenges posed by climate change, resulting in a substantial annual loss of up to 30% of global wheat productivity. As the benefits of the Green Revolution have largely plateaued, modern agricultural interventions are essential. Nanotechnology emerges as a promising frontier, offering the potential to revolutionize agriculture at every stage, from seed priming to post-harvest storage. In this study the Biogenic zinc oxide nanoparticles (ZnO-NPs) were successfully synthesized using environmentally friendly approaches involving plant extracts, yielding pure white nanopowder. Optimization based on physiochemical parameters identified Lantana camara leaf extract as the most effective source. Characterization revealed spherical rod-shaped nanoparticles with sizes ranging from 10 to 100 nm, displaying good colloidal stability and a negatively charged surface with multiple compounds influencing biological responses. The application of ZnO-NPs, particularly at 100 ppm concentration, significantly improved various seed growth parameters and total protein content. Genetic analyses demonstrated significant variability among wheat genotypes under both non-stress and heat stress conditions, providing opportunities for selective breeding. Heritability and genetic advance estimates highlighted spike length and grain yield as promising traits. Additionally, genotypic and phenotypic correlations unveiled the intricate relationships between agronomic traits, aiding targeted breeding strategies. Path analysis further elucidated the direct and indirect contributions of traits to grain yield, emphasizing the importance of biomass, effective tillers per plant, and spike length. Physiological and biochemical responses indicated that ZnO-NPs mitigated the adverse effects of heat stress on chlorophyll content, photosynthetic rate, relative water content, and cellular membrane stability, while enhancing proline, catalase peroxidase, and superoxide dismutase activities. Gene expression analysis of heat shock proteins (HSP17, Hsp23 and Hsp 70) in heat-tolerant and heat-sensitive genotypes exposed to varying heat shock treatments revealed distinct responses, with HSP17 showing the highest expression in PBW226 under stress conditions. Overall, this research demonstrates the potential of biogenic ZnO-NPs to enhance wheat resilience in the face of climate change and underscores nanotechnology's role in modern agriculture, contributing to global food security.