Lactarius ectomycorrhizae on Abies alba: morphological description, molecular characterization, and taxonomic remarks

Abstract

To date, the ectomycorrhizae formed by silver fir (Abies alba), an ecologically valuable and indigenous tree species in many European mountain forests, have been poorly investigated. We characterized the mycorrhizae formed by three Lactarius species (Lac. subsericatus, Lac. intermedius, Lac. salmonicolor) on silver fir, on the basis of material originating from central Italy. The identification of the fungal symbiont was achieved by means of morphoanatomical observations of mycorrhizae, and by comparison of ITS sequences obtained from mycorrhizae and sporocarps of putative fungal partners. Sequences also were obtained from specimens of the same species but from different geographic origin or from closely related Lactarius species. A maximum likelihood analysis of the data was performed. On the whole, the resultant tree is in good agreement with sporocarp and mycorrhiza morphology. RFLP patterns were calculated from sequence data. A discussion on the main morphoanatomical characters distinguishing the Lactarius ectomycorrhizae reported in this study from those already described belonging to related species, is also included. The accuracy of different methods to identify mycorrhizae formed by closely related Lactarius species on silver fir, are discussed.