Abstract The American strain S238N of

the ectomycor-rhizal fungus Laccaria bicolor (Maire) Orton has been used to inoculate Douglas-fir [Pseudotsuga menziesii (Mir.) Franco] plantations in France over the last two de-cades. Laccaria fruit bodies are scarce in mature planta-tions, which precludes further assessment of its persis-tence by fruit body surveys. Our objective was to devel-op new markers to identify this strain and its eventual non-fruiting progeny on root tips. We converted nine random amplified polymorphic DNA markers into se-quence characterized amplified region (SCAR) markers. Two of these SCAR markers enabled us to detect S238N on roots of seedlings and mature trees. No amplification of non-fungal (host plant, bacterial, etc.) DNA was ob-served. Moreover, both SCARs were amplified from Laccaria-like mycorrhizas in a Douglas-fir plantation in-oculated 14 years ago, demonstrating the long-term per-sistence of the inoculant strain. We also obtained a SCAR marker to detect one strain of European origin (L. bicolor 81306), indicating that SCARs are potential markers to type the naturally occurring genets. Thus, SCAR markers are of great value in studying the persis-tence of inoculant strains and the effects on local popula-tions of introducing foreign strains