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Title: A PRELIMINARY OVERVIEW OF THE DIAPORTHALES BASED ON SEQUENCES ANALYSES OF THE LARGE SUBUNIT OF THE NUCLEAR RIBOSOMAL DNA

Author
item Castlebury, Lisa
item Rossman, Amy
item Jaklitsch, Walter
item Vasilyeva, Larissa

Submitted to: Mycologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/4/2002
Publication Date: N/A
Citation: N/A

Interpretive Summary: Fungi cause billions of dollars damage to agricultural crops and forest trees around the world. Their classification and characterization are essential for the control of diseases caused by fungi yet for some groups of fungi relatively little is known. The Diaporthales include fungi that cause devastating diseases such as chestnut blight, soybean canker and dieback of fruit trees. In this research molecular characters were used to produce a classification for about 80 species in the Diaporthales. It was determined that a number of species are related to the chestnut blight fungus all having specific morphological and chemical similarities. The close relatives of the asexually reproducing fungus that causes dogwood anthracnose were determined but none were the sexual state of this fungus. Fungi that cause cankers of fruit trees were classified into two distinct groups. For the Diaporthales as a whole, six major lineages were defined based on both morphological and molecular characteristics. This research will be used to classify fungi belonging to the Diaporthales. As a result it will be possible for plant pathologists to accurately characterize fungi that cause diseases of crops and trees and thus to develop better control measures for these diseases.

Technical Abstract: The ascomycete order Diaporthales includes a number of plant pathogenic fungi, the most notorious of which is Cryphonectria parasitica, the chestnut blight fungus, as well as many asexually reproducing plant pathogenic fungi without known sexual states. Relationships among genera in the Diaporthales were evaluated as a basis for the recognition of families and to provide a taxonomic framework for the asexually reproducing diaporthalean fungi. The major lineages within the Diaporthales were determined based on a sequence analysis of the large subunit (LSU) of the nuclear ribosomal DNA. Analyses of 83 sequences representing 69 taxa confirm the Diaporthales as a well-supported order having bootstrap values of 100% in this study. In addition these results suggest the presence of at least six lineages within the Diaporthales. These lineages are recognized as the Gnomoniaceae sensu stricto, Melanconidaceae sensu stricto, Schizoparme complex including the anamorph genera Coniella and Pilidiella, Cryphonectria-Endothia complex, Valsaceae, and Diaporthaceae. Six teleomorphic and anamorphic taxa fell within the Diaporthales but were not allied with any of the major lineages.