Genetic Analysis of a Cross of Two Venturia inaequalis Strains that Differ in Virulence

A genetic map oflhe fungus Venlllria illaequalis based on the Bo-7 x Sp-7 cross linking 30 RAPD-PCR markers to the ITS-region. the mating-type locus and the virulence/ avirulence La the apple culLi var ʹBoskoopʹ was constructed . The map covers 270 cM and is divided into six linkage groups. The mating-type locus is Han ked by two RAPD-PCR markers in 28.9 and 18.9 cM distance. The ITS-region is loca ted on one chromosome. spans a length of7. 16 cM and is linked to a RAPD-PCR marker at 15.7 cM distance. The virulence/a virulence to ʹ Boskoopʹ is linked to a RAPD-PCR marker at 19.5 cM. Virulence to ʹGolden Deliciousʹ is unlinked . The relative positioning (linked or unlinked) or virulence/lOvirulence genes is important for tbe adaptation of V. illaequalis strains Lo new introduced host resistances or to new combina tions of host resistances genes