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United States Department of Agriculture

Agricultural Research Service

Title: Molecular Systematics of Fungal Plant Pathogens: Generalisations from Fusarium

Author
item O`donnell, Kerry

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: February 7, 2003
Publication Date: N/A

Technical Abstract: This presentation will focus on the importance of developing a robust phylogenetic framework for investigating species limits, evolution of virulence-associated factors such as toxins, host range, biogeography and global movement of agronomically important phytopathogens, drawing from examples of Fusarium. Amazing technological advances in molecular biology during the past fifteen years, including the polymerase chain reaction and automated DNA sequencing, have provided biologists with robust tools that are revolutionizing the whole field of fungal molecular systematics. Phylogenetic species recognition based on concordance of multigene genealogies represents a critical conceptual advance in species biology. Under this history-based concept, species form reciprocally monophyletic groups in multigene genealogies. Relationships of strains within a recombining species, however, yield a reticulate topology in a strict consensus tree inferred from the combined multigene DNA sequence data. Application of genealogical concordance phylogenetic species recognition within Fusarium has revealed that this genus is several times more speciose than currently recognized using morphology alone. These studies also have revealed that single-copy nuclear genes interrupted by introns have greater utility for investigating species boundaries than the often used internal transcribed spacer region (ITS) of the nuclear ribosomal rDNA. One of the major advantages of discrete DNA sequence data is that it is electronically portable via the Internet. Fungal pathogen databases such as the one being developed for Fusarium need to be Internet-based so that they can be made freely available and avoid duplication of effort, to help insure standardization of pathogen names, and so that they can be up-dated continuously.

Last Modified: 11/25/2014
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