| Species of Fusarium cause disease on plants, animals and humans, and many produce mycotoxins. Recent severe outbreaks of crown and stem rot of lisianthus were attributed to F. avenaceum. Fusarium solani has been associated with caladium tuber rot outbreaks in Florida. Three different studies involving molecular phylogenetics of Fusarium were carried out. In the first study, we sequenced parts of two genes, translation elongation factor 1-alpha (tef) and beta-tubulin (benA), in F. avenaceum isolates. Phylogenetic analyses showed F. avenaceum isolates to be monophyletic with strong bootstrap support and genealogical concordance. Isolates from lisianthus were scattered within the F. avenaceum clade. The low degree of phylogenetic divergence contrasted with a high degree of vegetative incompatibility structure among isolates from lisianthus. Pathogenicity tests of several F. avenaceum isolates including those from other hosts showed the ability to cause disease on lisianthus suggesting that any F. avenaceum is potentially a pathogen of lisianthus.; In the second study, we investigated the evolutionary origins of F. solani isolates from caladium. Portions of the benA and tef genes were sequenced in 57 isolates and a subset of 20 isolates were chosen to sequence the internal transcribed spacer regions (ITS) and nuclear large sub unit (NLSU) of the rRNA gene. The individual and combined analysis of the genes showed two new clades associated with caladium within clade 3 of the F. solani species complex (FSSC). There were significant differences in growth rate and pigmentation between clades suggesting that these were two different species that cause disease on caladium.; In the third study, we investigated the phylogenetics of F. solani isolates obtained from soil and perithecia found on bark and fruit from primary forests in Sri Lanka and Australia. Portions of the tef, ITS and NLSU genes were sequenced in over 100 of the isolates. All soil-derived and most ascospore isolates from Sri Lanka were in Clade 3 and Clade 2 respectively, while isolates from Australia were all in Clade 3. These results shed light on the possible taxonomic revision of the anamorph and teleomorph for F. solani, and epitypification of the type specimen of F. solani. |
