Pathotype separation of Plasmodiophora brassicae by the host plant

Different pathotypes existing in the field isolate 'e' of Plasmodiophora brassicae were separated by repeated propagation in resistant host plants or by inoculation with single spores. The resulting isolates were studied by combining the molecular markers of fingerprint-like patterns and characterization of pathogenic capacity using genetically homogenous Arabidopsis ecotypes under controlled environmental conditions, so that the selection of virulent pathotypes within resistant host plants could be demonstrated. These host-selected isolates shared the molecular and phytopathological characters of corresponding single-spore isolates.