Physio-biochemical and molecular effects of copper nanoparticle under salinity stress in Triticum aestivum L

Salinity stress induces oxidative damage and impairs plant productivity, necessitating innovative mitigation strategies. This study elucidates the novel role of foliar-applied copper oxide nanoparticles (CuONP: 0, 10, 20, 40 mg/L) in alleviating 200 mM NaCl-induced stress in two distinct wheat genotypes, Bezostaja-1 and K & imath;rm & imath;z & imath; K & imath;l & ccedil;& imath;k. We demonstrate, for the first time, that 20 mg/L CuONP optimally enhance salinity tolerance by uniquely modulating genotype-specific responses. In Bezostaja-1, CuONP reduced malondialdehyde (MDA) by 38 % and cell membrane damage (CMD) by 42 %, while increasing proline content by 55 % under salinity. K & imath;rm & imath;z & imath; K & imath;l & ccedil;& imath;k exhibited superior K/Na ratio (2.1-fold) and Cu uptake (1.8-fold) at 20 mg/L CuONP. Both genotypes showed upregulated expression of salinity-responsive genes (TaSOS1, TaNHX1) and antioxidant enzymes (SOD, CAT, APX) by 1.5-2.3-fold, correlating with improved biomass (27-33 %) and root architecture. The non-linear dose-response highlights 20 mg/L as the critical threshold for efficacy, beyond which benefits plateau. These findings establish genotype-specific CuONP mechanisms and provide a nanotechnology-driven strategy to enhance salt tolerance in wheat.