Identification of a novel Fusarium head blight resistance locus Fhb.Er-1StL from Elymus repens introgressed into wheat

Fusarium head blight (FHB) threatens wheat production worldwide, and major-effect resistance sources remain limited. Elymus repens (2n = 6x = 42, StStStStHH) is a perennial Triticeae species with potential for wheat improvement. Here, we characterized the genomic constitution of the wheat-E. repens partial amphidiploid P1142-1-2, which shows strong FHB resistance. P1142-1-2 carries the complete wheat genome plus seven pairs of E. repens-derived chromosomes or chromosome fragments containing St chromatin from 1St-7St. From crosses between P1142-1-2 and common wheat cv. Chuannong16, we identified two resistant derivative lines carrying either a 1StL isochromosome or a 1StL telosome. Genomic sequencing enabled the development of 17 1StL-specific PCR markers for precise detection of alien chromatin. Genetic analysis demonstrated that 1StL confers strong resistance to FHB in wheat. Diagnostic assays did not detect previously reported alien FHB resistance genes, indicating that 1StL carries a novel resistance locus, designated Fhb.Er-1StL. These materials and markers broaden the genetic basis of FHB resistance in wheat and provide useful resources for wheat improvement.