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ARS Home » Research » Publications at this Location » Publication #192968


item Aime, Mary

Submitted to: Mycologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/1/2006
Publication Date: 4/19/2007
Citation: Matheny, B.P., Curtis, J.M., Hofstetter, V., Aime, M.C., Moncalva, J. M., and others. 2007. Major Clades of Agaricales: A Multilocus Phylogenetic Overview. Mycologia. 98:982-995.

Interpretive Summary: Fungi with their minute, threadlike structures are essential for the growth of nearly all land plants especially trees growing in regions where nutrients are scarce. This required association of fungi with the roots of trees and crop plants is called mycorrhiza for myco = fungus and rhiza = root. Determining whether or not a fungus is mycorrhizal with a plant is not easy, yet this knowledge is essential for efficient management of forests, crops, and reforestation efforts. In this paper a number of fungi many of which are essential for plant growth are characterized and compared in order to determine how closely related they are to each other. These comparisons are made using portions of the genome that are sequenced. It was determined that some groups include only species that help plants grow while other groups of fungi only break down dead organic matter into essential nutrients. This research will be used by foresters and land-use managers for managing forests by understanding the essential relationship between fungi and plants.

Technical Abstract: Many taxonomic families of agarics are not monophyletic and require re-evaluation by molecular phylogenetic methods. Using over 5600 nucleotide characters from rpb1, rpb1-intron 2, rpb2 and 18S, 25S, and 5.8S ribosomal RNA genes, we recover six major clades of Agaricales with Bayesian and parsimony methods. These data support the monophyly of the Agaricales sensu Kühner, which we refer to as the Agaricoid clade. This group is composed of derived dark spored agarics, plus the Hydnangiaceae and Nidulariaceae. Most members of this clade possess multinucleate spores and an open-pore hilum. The Agaricoid clade is sister to the Tricholomatoid clade, which is made up of a restricted Tricholomataceae, plus the Mycenaceae, Lyophyllaceae, Entolomtaceae, and residual clitocyboid taxa. The Entolomataceae is recovered as monophyletic for the first time. The Marasmioid clade, a white-spored group dominated by numerous saprobic or parasitic taxa, is composed of basidiomycetes with a diverse fruit body form—pileate, resupinate, or cyphelloid—and diverse hymenophoral type—gilled, smooth, or poroid. Many cyphelloid lineages are concentrated in the Marasmioid clade. The Hygrophoroid clade consists of an expanded Hygrophoraceae, including many genera of the Tricholomataceae sensu Singer, and clavarioid fungi of the families Pterulaceae and Typhulaceae. The Pluteoid clade is composed of the Pluteaceae, Limnoperdonaceae, Amanitaceae, Pleurotaceae, and the genus Melanoleuca. The earliest diverging lineage of the Agaricales is the Plicaturopsidoid clade, which includes the non-agaric taxa Plicaturopsis crispa, Podoserpula pusio, Sclerotium rolfsii, and the Clavariaceae. One agaric genus from the Hygrophoraceae, Hygrotrama, is also represtented in the Plicaturopsidoid clade and closely related to the club and coralloid family Clavariaceae. Many subgroupings are recovered and discussed in terms of their morphological and ecological traits. The positions of the Macrocystidiaceae and Infundibulicybe gibba remain unresolved. At least eleven origins of the ectomycorrhizal habit have evolved in the Agaricales under equally weighted parsimony conditions, eight of them occurring in the derived Agaricoid plus Tricholomatoid clade alone. A family-based phylogenetic classification is sketched for the six major clades of Agaricales, in which 29 families, four autonomous tribes, and two informally named clades are recognized.