Phylogeny of Calonectria based on comparisons of beta-tubulin DNA sequences

Species of Calonectria represent an important group of plant pathogenic fun gi that cause serious losses to crops in tropical and subtropical climates. Because these fungi are difficult to identify, selected species were subje cted to DNA analysis with the aim of producing a more objective identificat ion technique. This was done by amplifying the 5' end of the P-tubulin gene from isolates representing more than 30 species of Calonectria. A neighbou r joining analysis was performed on a total data set of 86 isolates, while a representative subset of isolates was analysed by means of maximum parsim ony. Both analyses yielded dendrograms with concordant topology. Several cl ades were strongly supported by bootstrap, confirming the morphological and biological species concepts presently employed. At least two large groupin gs were evident and both contained small-spored, I-septate species. The onl y morphological character that correlated with DNA phylogeny was vesicle sh ape. These data support Calonectria as a monophyletic genus with Cylindrocl adium anamorphs. Furthermore, this study also emphasises the importance of vesicle morphology in identifying Cylindrocladium anamorphs, and hence spec ies of Calonectria.