Genetic Relatedness versus Biological Compatibility between Aspergillus fumigatusand Related Species

ABSTRACTAspergillussection Fumigaticontains 12 clinically relevant species. Among these Aspergillusspecies, A. fumigatusis the most frequent agent of invasive aspergillosis, followed by A. lentulusand A. viridinutans. Genealogical concordance and mating experiments were performed to examine the relationship between phylogenetic distance and mating success in these three heterothallic species. Analyses of 19 isolates from section Fumigatirevealed the presence of three previously unrecognized species within the broadly circumscribed species A. viridinutans. A single mating type was found in the new species Aspergillus pseudofelisand Aspergillus pseudoviridinutans, but in Aspergillus parafelis, both mating types were present. Reciprocal interspecific pairings of all species in the study showed that the only successful crosses occurred with the MAT1-2isolates of both A. parafelisand A. pseudofelis. The MAT1-2isolate of A. parafeliswas fertile when paired with the MAT1-1isolates of A. fumigatus, A. viridinutans, A. felis, A. pseudoviridinutans, and A. wyomingensisbut was not fertile with the MAT1-1isolate of A. lentulus. The MAT1-2isolates of A. pseudofeliswere fertile when paired with the MAT1-1isolate of A. felisbut not with any of the other species. The general infertility in the interspecies crossings suggests that genetically unrelated species are also biologically incompatible, with the MAT1-2isolates of A. parafelisand A. pseudofelisbeing the exception. Our findings underscore the importance of genealogical concordance analysis for species circumscription, as well as for accurate species identification, since misidentification of morphologically similar pathogens with differences in innate drug resistance may be of grave consequences for disease management.