Résumé
Deoxyribonucleic acid (DNA) markers have been used in many studies to distinguish related species of ectomycorrhizal fungi or genotypes of a single species. These markers have been designed to identify defined strains of ectomycorrhizal fungi in forest nurseries and within the complex microbial communities of reforestation sites and natural ecosystems. Various polymerase chain reaction (PCR)-based methods revealed sequence polymorphisms in nuclear and mitochondrial ribosomal DNA of ectomycorrhizal fungi that can be used as highly informative markers for the structure and dynamics of genomes at the level of communities and populations. Markers based on random amplified polymorphic DNA (RAPD) or on microsatellite-primed PCR are suitable for identifying clones (genotypes) and describing the differentiation of populations of ectomycorrhizal fungi. Here we describe the procedures that allow the rapid typing of an ectomycorrhizal isolate from vegetative mycelium, fruiting bodies, as well as a single ectomycorrhizal root tip. Specific applications illustrated are: identification of fungal species and isolates; analysis of the persistence and dissemination of introduced exotic strains; and detection of gene flow between introduced strains and local forest populations. (C) Inra/Elsevier, Paris