DETECTION OF DNA POLYMORPHISMS IN A SINGLE UREDINIOSPORE-DERIVED CULTURE OF CRONARTIUM-QUERCUUM F SP FUSIFORME

PCR (polymerase chain reaction) with single, arbitrarily chosen primers was used to detect DNA polymorphisms among 34 sibling gametothalli (single-basidiospore hyphal cultures) and spermatia (single drops of pycniospores) derived from a single-urediniospore culture of the fusiform rust fungus, Cronartium quercuum f. sp. fusiforme. Ten single-basidiospore hyphal cultures were distinguished by comparing nine polymorphic segments produced by four primers. Polymorphisms also were detected between 24 single drops of pycniospores collected from four different galls and drops within the same gall, revealing that phenotypes of galls were all different, and some contained more than one phenotype. The possibility of the presence of more than one genotype between and within galls reinforces a belief that traditional experiments on the genetics of host-pathogen interactions between Pinus and C. q. fusiforme cannot be carried out using current methods of inoculation. The ability to identify genetic variation within a single urediniospore-derived culture of C q. fusiforme should benefit efforts to minimize heterogeneity in populations of basidiospores used in artificial inoculations. The polymorphisms can be applied in studies of population variation, used for genetic mapping, and used in resolving specifics of sexuality and the ploidy level of various stages of the life cycle.