Both stable and unstable QTLs for resistance to powdery mildew are detected in apple after four years of field assessments

摘要: Powdery mildew, caused by the ascomy- cete fungus Podosphaera leucotricha, is one of most damaging diseases apple worldwide. Poly- genically determined resistance might contribute to a significant increase this disease in new cultivars. A quantitative trait locus (QTL) anal- ysis was performed an F1 progeny derived from cross between cultivar Discovery and hybrid TN10-8. mildew incidence assessed during four years (five seasons) spring and/or autumn French local orchard. Seven additive dominant QTLs were detected over five seasons, with effects (R 2 ) ranging 7.5% 27.4% phenotypic variation. Two QTLs, on linkage groups (LGs) 13, con- sistently identified accounted together 29% 37% variation according year assessment. The other (LGs 1, 14), two (LG10), or three 8, 17) seasons. Their instability indicated changing genetic determinism assess- ment, for which several hypotheses may be put for- ward. LGs 8 mapped close clusters gene analogs (RGAs) major genes scab previ- ously identified. stable strong effect QTL located LG are special interest breeding purposes, especially if combined genes.