Identification of a novel QTL associated with Fusarium head blight resistance on chromosome 3B in common wheat.

Key message: A novel Fusarium head blight resistance locus, QFhb-3BL, was identified and fine-mapped in common wheat. Identification and utilization of major resistance genes is key to developing new wheat cultivars/lines with improved Fusarium head blight (FHB) resistance. In this study, a moderately FHB-resistant cultivar Yangmai 16.2 (YM16.2) was crossed with a susceptible cultivar Yanzhan 1 (YZ1) to create a recombinant inbred line (RIL) population. Using bulk segregant analysis sequencing (BSA-seq) and linkage analysis, a new FHB quantitative trait locus (QTL) named QFhb-3BL, contributed by YM16.2, was identified. Eight Kompetitive Allele-Specific PCR (KASP) markers were used to detect homozygous recombinants in the derived lines of the remaining heterozygous line (RHL). QFhb-3BL was finely mapped to the 751.10-756.45 Mb interval, which contains 75 high-confidence genes. Through variation analysis of the candidate region and RNA sequencing (RNA-seq), we identified 11 genes with sequence variations and 14 genes expressed within the fine-mapping interval, with four genes overlapping between the two groups. KASP markers for the candidate gene TraesCS3B03G1226500 were validated in 103 wheat cultivars/lines, and lines carrying these markers showed a 38.89% reduction in FHB severity. This study provides a foundation for QFhb-3BL cloning and an effective marker for FHB resistance breeding.