Identification of a quantitative trait locus for resistance to Sitodiplosis mosellana (Gehin), the orange wheat blossom midge, in spring wheat

P>Sitodiplosis mosellana (Gehin), the orange wheat blossom midge (OWBM), causes sporadic damage to wheat (Triticum aestivum L.) throughout the northern hemisphere. Cultivars have been shown to differ in levels of OWBM infestation. In this experiment, a recombinant inbred line (RIL) population derived from a cross between cultivars representing extremes of OWBM infestation was tested for 2 years in Creston MT. Parental cultivar 'Reeder' showed average infestation levels approximately three times less than 'Conan' in both years. The RIL population showed significant variation, with heritability of 0.75 in 2008 and 0.26 in 2009. A genetic map of the population identified a major quantitative trait locus (QTL) on chromosome 1A (QSm.mst-1A), controlling 17% and 34% of the variation in 2008 and 2009, respectively. Near isogenic lines developed for this QTL in three backgrounds showed a significant effect of the QTL, with the 'Reeder' allele reducing infestation by approximately 42%. Differential infestation conferred by the QTL QSm.mst-1A may complement previously identified resistance due to antibiosis.