A genetic analysis of the resistance in barley to Soil-borne wheat mosaic virus

Soil-borne wheat mosaic virus (SBWMV), a ubiquitous pathogen commonly encountered in temperate regions of the Northern hemisphere, can damage a number of economically important cereal crops, notably wheat and barley. Given that the plasmodiophorid cercozoan Polymyxa graminis, which acts as the vector of SBWMV, can survive in the soil for many decades, the only feasible control measure is the deployment of resistant cultivars. Here, a quantitative trait locus (QTL) approach was taken to characterize the genetic basis of the SBWMV resistance exhibited by the barley cultivar Haruna Nijo. The analysis revealed that between 33% and 41% of the variation for the measure chosen to represent resistance was under the control of a gene(s) mapping to a region at the distal end of the short arm of chromosome 2H. In contrast to most of the genes known to encode resistance to soil-borne mosaic viruses, the allele specifying resistance was dominant over those present in a susceptible genotype.