Genomic loci for priming-induced powdery mildew resistance and plant biomass in wheat

Blumeria graminis f. sp. tritici ( Bgt ), the causal agent of powdery mildew in wheat, poses a serious threat to yield stability. Although several resistance genes have been identified, many became ineffective due to pathogen adaptation. Priming, a biological process that enhances the defense capacity of plants, has emerged as a promising plant protection strategy. The root-endophytic fungus Serendipita indica is known to induce priming in various host plants. In this study, we investigated S. indica -mediated resistance to Bgt across a genetically diverse panel of 175 winter wheat genotypes. Disease severity was quantified and nine genotypes exhibited significant (p < 0.05) differences in Bgt susceptibility following S. indica treatment. Six genotypes showed reduced, three increased levels of infection. Additionally, shoot (SFW) and root fresh weight (RFW) measurements revealed genotype-specific growth responses to S. indica . A genome-wide association study identified quantitative trait loci (QTLs) significantly associated (LOD ≥ 3) with Bgt resistance, SFW, and RFW under control and primed conditions. Notably, eight QTLs were associated with SFW, two with RFW, and fifteen with Bgt resistance in primed plants, with multiple loci mapped to chromosome 7 A. Across all QTLs, 30 candidate genes were identified, including those involved in resistance pathways such as Flavonoid 3'-hydroxylase , Chaperone protein DnaJ , and Glutathione S- transferase . These findings indicate genetic variation for priming in wheat. The identified candidate genes provide valuable targets for further investigation into the mechanisms of microbe-induced priming and offer a foundation for breeding for Bgt- resistant, S. indica -responsive wheat cultivars with enhanced resilience to biotic stress. • S. indica -mediated resistance to Bgt across a genetically diverse panel of 175 winter wheat genotypes • Disease severity was quantified and nine genotypes exhibited significant (p < 0.05) differences in Bgt susceptibility following S. indica treatment • Shoot (SFW) and root fresh weight (RFW) measurements revealed genotype-specific growth responses to S. indica • Eight QTLs were associated with SFW, two with RFW, and fifteen with Bgt resistance in primed plants, with multiple loci mapped to chromosome 7 A