Bi-Parental Mapping and Validation of Barley Yellow Dwarf Virus Resistance Locus in Barley Cultivar 'Lightning'.

Barley Yellow Dwarf Virus (BYDV), caused by multiple viruses within the Luteoviridae family and primarily transmitted by aphids, is among the most economically significant viral diseases impacting barley (Hordeum vulgare subsp. vulgare) production worldwide, resulting in stunted growth, leaf discoloration, and considerable reductions in grain yield. To validate previously reported BYDV resistance quantitative trait loci (QTL) in the barley cultivar 'Lightning', a doubled haploid (DH) population (n = 131) derived from a cross between 'Lightning' and the susceptible line 'DH141222' was evaluated for resistance to BYDV. Field trials were planted in the early fall of 2023 and 2024 to assess plots under natural BYDV infection conditions during the late spring of 2024 and 2025, respectively. Aphid presence and BYDV infection were confirmed through field evaluations and PCR analysis. Phenotypic traits measured included BYDV severity, plant height, heading date, grain protein content, grain plumps, test weight, and grain yield. A notable QTL associated with BYDV resistance, grain yield, and plant height was identified on chromosome 2H, with significant LOD scores of 20.7 (BYDV severity), 30.86 (grain yield), and 8.22 (plant height) (α = 0.01). This region was delimited to 2.3 Mb, containing 57 genes. This study significantly enhances our knowledge of viral resistance mechanisms in barley and supports targeted genetic improvement efforts to mitigate BYDV-related yield losses.