A single QTL on chromosome 6DS derived from a winter wheat cultivar 'OW104' confers resistance to Wheat yellow mosaic virus .

Wheat yellow mosaic (WYM) is a soilborne disease caused by Wheat yellow mosaic virus (WYMV). Symptoms include yellow mosaic coloring of leaves, stunting, and growth inhibition. Severe infection may result in yield loss. WYM is one of the most serious diseases affecting wheat production in East Asia. The most effective control is through breeding resistant cultivars. A winter wheat cultivar, 'OW104', shows little to no symptoms in heavily WYMV-infested fields in Hokkaido, Japan. Here we detected Qym4, a QTL accounting for 45%-57% of WYMV resistance, in the vicinity of the markers Xcfd49, Xbarc183, and Xgpw4357 on wheat chromosome arm 6DS. F3 progenies with 'OW104' allele at Qym4 showed significantly higher resistance than those with 'Hokushin' homozygote or heterozygote. We developed 'Hokushin' near-isogenic lines by backcrossing with 'Hokushin' as the recurrent parent and 'OW104' as the resistance donor. All the WYMV-resistant BC5F1/BC4F1 plants carried 'OW104' allele only at Xcfd49. Our results suggest that the introduction of Qym4 confers resistance to WYMV in winter wheat.