Ectomycorrhization of Tricholoma matsutake and two major conifers in Finland—an assessment of in vitro mycorrhiza formation

This study aimed to test the ability of Tricholoma matsutake isolates to form mycorrhizas with aseptic seedlings of Pinus sylvestris L. and Picea abies (L.) Karst. Germinated seedlings of Scots pine and Norway spruce were separately inoculated with either isolates originating from Finland or Japan. Eight months after inoculation, the Finnish isolate had formed a sheath and Hartig net on both host species. Ectomycorrhizal Scots pine seedlings inoculated with the Finnish isolate showed the same shoot height and dry mass as the controls. Ectomycorrhizal Norway spruce seedlings inoculated with the Finnish isolate had similar shoot height but slightly less dry mass than the control seedlings. For both tree species, inoculation with the Finnish isolate resulted in reduced total nitrogen content per seedling, but carbon content was unaffected. Inoculation with the Japanese isolate resulted in an initial Hartig net-like structure in pine but not in spruce. No typical Hartig net was observed on either tree species. Furthermore, seedlings of both species inoculated with the Japanese isolate showed significantly reduced growth, dry mass, nitrogen, and carbon content per seedling and shoot height (in spruce) compared to the controls. This study documents and describes the in vitro ectomycorrhization between T. matsutake and Scots pine or Norway spruce and the variable mycorrhizal structures that matsutake isolates can form.