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Title: AN OVERVIEW OF THE HIGHER-LEVEL CLASSIFICATION OF UREDINIOMYCOTINA BASED ON COMBINED ANALYSES OF NUCLEAR LARGE AND SMALL SUBUNIT RDNA SEQUENCES

Author
item Aime, Mary
item HIBBETT, DAVID - CLARK UNIV,WORCHESTR,MA M
item MATHENY, BRANDON - CLARK UNIV,WORCHESTR,MA
item Henk, Daniel
item FRIEDERS, ELIZABETH - UNIV OF WISC PLATTEVL,WI
item SZABO, LES - USDA-ARS-CDL, ST PAUL,MN

Submitted to: Mycologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/7/2006
Publication Date: 4/19/2007
Citation: Aime, M.C., Hibbett, D., Matheny, B.P., Henk, D.A., Frieders, E.M., Szabo, L.J. 2007. An overview of the higher-level classification of urediniomycotina based on combined analyses of nuclear large and small subunit rDNA sequences. Mycologia. 98:896-905.

Interpretive Summary: Fungi cause billions of dollars damage to agricultural crops each year. In addition, they can greatly hinder the export of agriculturally commodities from the U.S. to other counties. In order to control diseases caused by fungi both in the U.S. and abroad it is necessary to identify and characterize fungal species that cause diseases of crops. In this paper a number of rust fungi 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 most of the rust fungi are relatively closely related to each other especially those that grow on living plants. Within the rust fungi several small groups are related to the rusts that grow on living plants but occur on insects and dead plant material. Knowledge of the characteristics and relationships of rust fungi to each other is important and will be used by plant pathologists who breed for resistance to the diseases caused by rust fungi.

Technical Abstract: In this study we provide a phylogenetically based introduction to the classes and orders of Urediniomycotina. The Urediniomycotina are a large and incredibly diverse group that make up one of the three subphlya of Basidiomycota. More than 8,000 species of Urediniomycotina have been described; the overwhelming majority of these (~ 90%) belong to a single order, the Uredinales, or rust fungi. Most of the described Urediniomycotina are biotrophic; a few are presumably saprotrophic. Members of the Uredinales are especially important phytopathogens that have had a major economic impact on some of the world’s most important agricultural crops. Diverse approaches have been used to delimit taxa within the Urediniomycotina and no consensus has yet been reached regarding higher-level classification for these fungi. We have assembled a dataset of previously published and newly generated sequence data from two nuclear rDNA genes (large subunit and small subunit) including exemplars from all known major groups in order to test hypotheses about evolutionary relationships amongst the Urediniomycotina. The utility of combining fuller-length nuc-lsu sequences with complete nuc-ssu sequences for resolution and support of nodes is discussed. The major taxonomic differences between former classifications and that of the present study are that more clades are recognized as formal taxa in this classification and some clades formerly ranked as subclasses are here elevated to the rank of class. In total, the present classification includes five major clades ranked as class (Agaricostilbomycetes, Atractiellomycetes, Cystobasidiomycetes, Microbotryomycetes, and Urediniomycetes) containing eleven orders. Our study confirms the Urediniomycotina as a monophyletic group that diverged early from the other two subphyla of Basidiomycota.