Submitted to: Mycological Society of America
Publication Type: Abstract Only
Publication Acceptance Date: August 7, 1997
Publication Date: N/A
Technical Abstract: Fusarium oxysporum Schlecht. is best known as one of the most successful plant pathogens in terms of its abundance and diversity. This diversity is reflected in the over 80 special forms (i.e., formae speciales) described for this vascular wilt pathogen. Each forma specialis is distinguished by a unique host range and may consist of one or more vegetative compatibility groups (VCGs) and pathogenic races. Numerous studies have documented considerable genetic diversity within nonphytopathogenic strains of F. oxysporum. In addition, strains of F. oxysporum are increasingly implicated in mycotic infections of humans and other animals. In taxonomic practice, many researchers use Snyder and Hansen's emendation of F. oxysporum (Amer. J. Bot. 32: 657-666. 1945) which includes all of the species recognized in the infrageneric group called Section Elegans (Wollenweber and Reinking, 1935). In this molecular phylogenetic study, DNA sequences from the mitochondrial small subunit ribosomal DNA and from two protein-encoding genes were used to infer phylogenetic relationships, using different tree-building methods and measures of clade stability, to address the following questions: 1. Is F. oxysporum sensu Snyder and Hansen a complex species? 2. Is Section Elegans monophyletic? 3. Are formae speciales natural groupings? and 4. How are strains from human infections related to those from other sources?