Pear scab resistance QTLs via a European pear (Pyrus communis) linkage map

Pear scab caused by Venturia pyrina is an economically important disease throughout the world and can cause severe crop loss in susceptible cultivars. The varying range of susceptibility to pear scab in F1 populations has made it possible to identify quantitative trait loci (QTLs). Ninety-five seedlings derived from the cross ‘Abbè Fétel’ (AF) × ‘Max Red Bartlett’ (MRB) were evaluated for scab resistance in greenhouse tests, with 39% being classified as resistant, 33 as moderately susceptible and 28 as highly susceptible. Amplified fragment length polymorphisms (157) and simple sequence repeats (41) were used to construct two maps, one of 908.1 cM (AF) and the other of 879.8 cM (MRB). The analysis of the resistance data collected made it possible to identify two major QTLs on linkage groups 3 and 7 associated with resistance to V. pyrina. Both QTLs explained 88% of the phenotypic variance and the log of odds values were higher than 10, suggesting the involvement of two major genes in pear scab resistance.