|1||Department of Plant and Microbial Biology, University of California, Berkeley CA 94720-3102|
|2||CESAC/CNRS, Université Paul Sabatier/Toulouse III, 29 rue Jeanne Marvig, 31055 Toulouse Cedex 4, France|
|3||NASA-Ames Research Center, MS-239-4, Moffett Field, CA 94035-1000|
|4||Department of Biology, Indiana University, Bloomington IN 47405|
|5||Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara CA 93106|
|6||USDA Forest Service, Forest Science Laboratory, Corvallis OR 97331|
|7||Department of Botany and Plant Pathology, Oregon State University, Corvallis OR 97331|
|8||Fox Chase Cancer Center, 7701 Burholme Avenue, Philadelphia PA 19911|
We have assembled a sequence database for 80 genera from the Hymenomycete lineage of the Basidiomycota for a small region of the mitochondrial large subunit rRNA gene. Our taxonomic sample is highly biased toward known ectomycorrhizal (EM) taxa, but also includes some related saprobic species. This gene fragment can be amplified directly from mycorrhizae, sequenced, and used to determine the family or subfamily level for many unknown mycorrhizal basidiomycetes. The method is robust to minor sequencing errors, minor misalignments, and method of phylogenetic analysis.
Evolutionary inferences are limited by the small size and conservative nature of the gene fragment. Nevertheless two interesting patterns emerge: 1) The switch between ectomycorrhizae and saprobic lifestyles appears to have happened convergently several and perhaps many times. 2) At least five independent lineages of ectomycorrhizal fungi appear to have radiated at about the same time.