Identification and characterization of a novel QTL for barley yellow mosaic disease resistance from bulbous barley.

Winter barley (Hordeum vulgare) production areas in the middle and lower reaches of the Yangtze River are severely threatened by barley yellow mosaic disease, which is caused by Barley yellow mosaic virus and Barley mild mosaic virus. Improving barley disease resistance in breeding programs requires knowledge of genetic loci in germplasm resources. In this study, bulked segregant analysis (BSA) identified a novel major quantitative trait loci (QTL) QRym.ZN1-7H for barley yellow mosaic disease resistance in an F₂ population derived from the cross between "Nongke 1-6" (H. vulgare) and "Zaoshu 3" (H. vulgare). This QTL, originating from bulbous barley (Hordeum bulbosum), demonstrated stability and was further validated in another F₂ population derived from the cross between "Nongke 2-6" (H. vulgare) and "Supi 1" (H. vulgare). QRym.ZN1-7H accounted for 10.61%-19.34% of the phenotypic variance. The QTL was further fine mapped to the 14- to 39-Mb interval on barley chromosome 7H. Transcriptome analysis identified 53 and 35 differentially expressed genes in roots and leaves (at QRym.ZN1-7H locus), respectively, with nine genes differentially expressing in both tissues. HORVU.MOREX.r3.7HG0650990, a member of the disease resistance protein family (NBS-LRR class), is the most likely candidate gene for QRym.ZN1-7H. Enrichment analysis indicated that QRym.ZN1-7H may be involved in signal transduction in plant innate immune response. This study laid a foundation for barley disease resistance breeding.