Recombination in Calonectria morganii and phylogeny with other heterothallic small-spored Calonectria species

The Calonectria morganii cultures studied were isolated from several hosts in the USA. Isolates were mated in all combinations, and one successful mating was selected to establish whether recombination occurred. RAPD and mating type data of parental isolates and progeny confirmed C. morganii to have a heterothallic mating system. Furthermore, to infer the phylogenetic relationships of C. morganii with morphologically similar Calonectria spp., DNA sequences of the ribosomal 5.8S RNA gene and the flanking internal transcribed (ITS) spacers, as well as part of the high mobility group (HMG) box (forming part of the MAT2 mating type gene) and the P-tubulin gene, were analyzed. Maximum parsimony yielded concordant trees for all three data sets. These data supported the morphological and biological species concepts proposed for C. morganii and other Calonectria species with, similar, small-spored Cylindrocladium anamorphs.