Resistance to late blight in Solanum bulbocastanum is mapped to chromosome8

Somatic hybrids between potato and Solanum bulbocastanum, a wild diploid (2 n=2x=24) Mexican species, are highly resistant to late blight, caused by Ph ytophthora infestans. Both randomly amplified polymorphic DNA (RAPD) and re striction fragment length polymorphism (RFLP) markers that are closely link ed to the resistance have been noted by analysis of three different backcro ss-2 populations derived from two different somatic hybrids. With reference to previously published potato and tomato maps, resistance appears to be o n the long arm of chromosome 8 and is flanked by RFLP markers CP53 and CT64 . In a population of BC2 plants derived from a cross between the BC1 line J 101K6 [(S. tuberosum PI 303900+S. bulbocastanum PI 243510) xKatahdin)]xAtla ntic, late blight resistance cosegregated with RFLP marker CT88 and RAPD ma rker OPG02-625.