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United States Department of Agriculture

Agricultural Research Service

Research Project: Genomic Analyses and Management of Agricultural and Industrial Microbial Genetic Resources and Associated Information

Location: Bacterial Foodborne Pathogens & Mycology Research Unit

Title: How does the phylogenetic species concept correlate with biological characteristics of the pathogenic species in Aspergillus section Fumigati?

Authors
item Sugui, J -
item Figat, A -
item Kwon-Chung, K -
item Peterson, Stephen
item Mellado, E -
item Cuenca-Estrella, M -

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: March 1, 2014
Publication Date: March 1, 2014
Citation: Sugui, J.A., Figat, A., Kwon-Chung, K.J., Peterson, S.W., Mellado, E., Cuenca-Estrella, M. 2014. How does the phylogenetic species concept correlate with biological characteristics of the pathogenic species in Aspergillus section Fumigati? [abstract]. Advances Against Aspergillosis Conference.

Technical Abstract: Phylogenetic analysis confirmed A. fumigatus, A. lentulus, and A. viridinutans are phylogenetically distinct and also showed that the Aspergillus unsp. isolates form an independent clade, apart from the other three Aspergilli. All isolates were able to grow at temperatures ranging from 25 to 42oC except A. viridinutans, whose maximum growth temperature was 37oC. Highest resistance to amphotericin B, itraconazole, and voriconazole was found among the Aspergillus unsp. isolates followed by A. lentulus, A. fumigates, and A. viridinutans in decreasing order. Virulence assays in larvae of G. mellonella and chronic granulomatous disease (CGD) mice showed that A. lentulus and A. viridinutans were less virulent than A. fumigatus. Among the four Aspergillus unsp. strains, two were more virulent than A. fumigatus in G. mellonella. In CGD mice, however, all four were avirulent. Assays in non-neutropenic balbC mice immunosuppressed with hydrocortisone revealed that all species, except for A. viridinutans, were equally virulent. Mating was not observed for A. fumigatus × A. viridinutans, A. fumigatus × A. lentulus, or A. lentulus × A. viridinutans. The complete sexual cycle was only observed in a cross between one of the Aspergillus unsp. strains (strain labeled as ASP1) with A. fumigatus and in ASP1 × A. viridinutans. Scanning electron microscopy image (SEM) morphology of the ascospores produced by ASP1 × A. fumigatus was clearly distinct from the ascospore morphology produced by mating between A. fumigatus isolates. Inter-species mating between A. fumigatus and ASP1 (which is phylogenetically more distant from A. fumigatus than A. lentulus) suggests that ASP1 is biologically close enough to A. fumigatus to produce hybrid progeny when mating type incompatibility can be overcome. Our findings underscore the importance of weighing both genetics and biology in understanding each taxon. It will be interesting to know whether the inter-species F1 hybrids created in the ASP1 × A. fumigatus cross are fertile. The analyses with these hybrids are in progress.

Last Modified: 9/10/2014
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