Quantitative trait loci associated with drought stress tolerance in wheat primed with zinc oxide nanoparticles at seed germination and seedling stages

Wheat is a major global staple crop, yet its productivity and nutritional quality are increasingly threatened by drought, raising serious food security concerns. Nanotechnology, particularly zinc oxide (ZnO) nanoparticle-based nano-priming, offers a promising strategy to improve germination, growth, and stress tolerance. Sixty-seven genotypes (65 double haloid (DH) lines + two parental lines) were phenotypically evaluated under four treatments: control (C), drought (D; PEG = 18 %), ZnO-NPs priming, and combined drought plus ZnO-NPs (D + ZnO-NPs). Twenty-two morphological traits were assessed, and QTL mapping was conducted using 3,567 SNP markers. Genotypes exhibited substantial variation, and treatments differed significantly across traits. Drought stress severely reduced performance, whereas ZnO-NPs priming improved germination and seedling establishment under both NP and NP + D conditions. The multi‑trait selection index was applied to all 65 lines, from which the ten most drought‑tolerant genotypes were identified. Of the 65 lines, 63 DH lines were used for QTL detection. Single-marker analysis revealed 12 QTLs for 22 traits across four environments. Functional annotation of 30 candidate genes indicated roles in transcriptional regulation, signal transduction, metabolism, RNA processing, and stress adaptation. Integrating molecular tools with nanotechnology provides a robust framework for wheat improvement. The identified superior genotypes, carrying key alleles for drought tolerance, represent valuable resources for breeding drought-resilient cultivars.ِ