Identification and transfer of resistance to Fusarium head blight from Elymus repens chromosome arm 7StL into wheat

Fusarium head blight (FHB), mainly caused by Fusarium graminearum, is one of the most destructive fungal diseases affecting global wheat production. Elymus repens (2n=6×=42, StStStStHH), a wild relative of wheat, exhibits numerous biotic and abiotic stress resistance characteristics. In previous studies, FHB resistance of E. repens has been transferred into common wheat through a wheat–E. repens partial amphidiploid and derivative lines. This study reports the development, characterization, and breeding utilization of K140-7, a novel wheat–E. repens translocation line conferring resistance to FHB. Genomic in situ hybridization (GISH) and fluorescence in situ hybridization (FISH) analyses demonstrated that K140-7 contained 40 common wheat chromosomes and two 7D·St translocation chromosomes. Subsequent characterization using oligonucleotide-FISH painting and single-gene FISH markers confirmed that the 7D fragment was a 7D short arm and the St fragment was a 7St long arm. Therefore, K140-7 was further identified as a 7DS·7StL translocation line with genetic compensation. Wheat 55K SNP array analysis of K140-7 demonstrated the 7DS·7StL translocation event. Field evaluations demonstrated that K140-7 exhibits agronomic performance comparable to its wheat parent. Based on St reference genome of Pseudoroegneria libanotica, 21 simple sequence repeats (SSR) markers specific to 7StL were developed. Genetic analysis established that 7StL confers FHB resistance and carries the dominant FHB resistance locus, designated as QFhb.Er-7StL. Introgression of QFhb.Er-7StL into elite wheat cultivars has generated three second-generation 7DS·7StL translocation lines with enhanced agronomic traits. This study provides valuable novel germplasms and specific molecular markers for FHB resistance breeding in wheat.