A new gene for resistance to Dysaphis pyri in pear and identification of flanking microsatellite markers

Dysaphis pyri is an important aphid pest of European pear (Pyrus communis) cultivars, none of which are currently reported to be resistant. In this study, we produced a progeny of the European pear Comice crossed with an accession of snow pear (Pyrus nivalis) that segregated for resistance to D. pyri in a Mendelian fashion, indicating the presence of a major gene, Dp-1. Following screening of the parents and seedlings with microsatellite markers, cosegregation analysis indicated that Dp-1 is flanked by NH006b and NH014a on linkage group 17, 2.3 and 3.6 cM away, respectively. Evidence is also presented for the duplication of linkage groups 9 and 17, which is a consequence of the allopolyploid origin of pear.