Genome-Wide Association Analyses Identify Hydrogen Peroxide-Responsive Loci in Wheat Diversity

Hydrogen peroxide (H₂O₂) is a signaling molecule that plays a crucial role in plant growth and development against different abiotic stresses. Identifying genetic factors associated with H₂O₂ regulation and homeostasis can provide valuable insights for improving stress tolerance. Here, we explored genetic diversity of root and shoot traits mediated by H₂O₂ using a global diversity panel of 150 bread wheat cultivars. The H₂O₂ treatment significantly reduced root and shoot growth. We calculated relative values and stress tolerance index (STI) of root and shoot traits and performed genome-wide association studies (GWAS). This led to identification of 108 marker-trait associations including the topmost associations on chromosomes 3B, 2A, 5A, 3B, 5D, 5A, 6B, 4B, and 3B for relative root length, STI root length, relative shoot length, STI shoot length, relative root fresh weight, relative shoot fresh weight, STI shoot fresh weight, and relative and STI root-shoot ratio, respectively. Linkage disequilibrium analysis revealed that major alleles of significant markers were linked with high relative values and STIs for all traits except for relative root length and relative root-shoot ratio. The selected candidate genes were involved mostly in metal ion binding, transmembrane transport, oxidation-reduction process, protein phosphorylation, DNA, and ADP binding processes. These findings provide a fundamental basis for functional analysis of putative candidate genes linked to H₂O₂-mediated root-shoot growth of wheat. The result will also help to construct genetic map for H₂O₂-mediated root-shoot growth variation.