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Evolution of the Aspergilli: stuff for genomicists to think about David M. Geiser Penn State University, USA

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Presentation on theme: "Evolution of the Aspergilli: stuff for genomicists to think about David M. Geiser Penn State University, USA"— Presentation transcript:

1 Evolution of the Aspergilli: stuff for genomicists to think about David M. Geiser Penn State University, USA

2 Aspergillus evolution What is Aspergillus? The major players in the genus and how are they related Interesting comparative questions about Aspergillus Studying evolution using genomics and studying genomics using evolution

3 What is Aspergillus? Aspergillus is a Eurotiomycete (or Plectomycete) Aspergillus species appear to have a common evolutionary origin –this is a weak inference Aspergillus species are diverse in their life histories –Homothallic –Heterothallic –Not seen to undergo sex Nine different described sexual stages (Emericella, Eurotium, Neosartorya, Petromyces, Fennellia, Sclerocleista, Warcupiella, Hemicarpenteles, Chaetosartorya)

4 Aspergillus is a Eurotiomycete Geiser and Lo Buglio S rDNA

5 Eurotiomycetes Thallic (Ascosphaerales, Onygenales) and Phialidic (Eurotiales) anamorphs Asci produced naked, in wefts of hyphae (gymnothecia) or in a solid enclosed fruiting body (cleistothecia) Cleistothecia may be borne in a stroma Many human and animal pathogens –Onygenales: Cocci, Histo, Blasto, dermatophytes –Eurotiales: Aspergillus, P. marneffei Very chemically creative An ectomycorrhizal fungus! (Elaphomyces) NO LICHENIZED FUNGI Osmophiles, thermophiles Industrial fungi

6 Conidiation in the Plectomycetes thallic (T): Onygenales, Ascosphaerales blastic (B): Eurotiales B B B B T T T Geiser and LoBuglio 2001 biseriate uniseriate

7 Ascomatal types in the Eurotiomycetes cleistothecia borne in a stroma (C/S) cleistothecia not borne in a stroma (C) stroma, with no cleistothecia (S) no cleistothecia and no stroma (N) C/S S S C C C N nutriocyte Geiser and LoBuglio 2001 Emericella Petromyces Onygena Trichocoma Eupenicillium Eurotium Gymnoascus Monascus Byssochlamys Ascosphaera

8 Sexual stages associated phylogenetically with important Aspergillus spp. Emericella and Aspergillus nidulans –True cleistothecium surrounded by a stroma of hülle cells Petromyces and A. flavus/oryzae/parasiticus/niger (?) –Cleistothecia embedded in a stroma (sclerotia) Neosartorya and A. fumigatus –Cleistothecia/gymnothecia with wall composed of cottony hyphae.

9 Aspergillus phylogenetics Not a lot of data useful for inferring large- scale relationships Take many of the trees I show with a grain of salt…

10 Aspergillus -- monophyletic? Tamura, M. Kawahara, K. Sugiyama, J S rDNA

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12 Aspergillus 25S rDNA tree Based on a single locus, ~600 bp Backbone of tree gets poor support Major traditional species groups are supported The morphologists did/are doing a pretty good job

13 Petromyces sexual stage multiloculate stroma Emericella sexual stage cleistothecium surrounded by hülle cells (stroma) Neosartorya sexual stage cleistothecium composed of cottony hyphae Eurotium sexual stage cleistothecium, no stroma Fennellia sexual stage Chaetosartorya sexual stage Warcupiella Sclerocleista

14 psychrotolerance Xerophilicty/tolerance heat-resistant ascospores Thermotolerance heat-resistant ascospores Subgenus Circumdati: Association with plants,seeds

15 The players in Aspergillus genomics Aspergillus nidulans –Emericella clade –Aspergillus nidulans group –Aspergillus section Nidulantes Aspergillus fumigatus Aspergillus oryzae

16 Emericella clade A. nidulans A. sydowii - coral pathogen Hülle cells Homothallics Putative asexuals Heterothallic NJ analysis of Steve Petersons 25S data

17 Aspergillosis of sea fan corals Kiho Kim Aspergillus sydowii in culture: a relative of A. nidulans! Aspergillosis of sea fan coral Geiser, D.M. Ritchie, K. Smith, G. Taylor, J.W. Nature, 1998

18 Sexual versus asexual strategies Aspergillus heterothallicus - described by June Kwon-Chung (Raper and Fennell 1965) One of three known heterothallic species (other two are Neosartoryas, clademates with A. fumigatus) Known asexuals should be predicted to be recombining: –Population genetic evidence: a rich literature Taylor et al. 2000, Annu. Rev. Phytopath. –MAT locus molecular genetics/phylogenetics Turgeon, Berbee and others Homothallics do not necessarily outcross less than heterothallics!

19 Known heterothallics

20 Early events in ascus development in the Eurotiales: designed for homothallism? Benjamin, 1955

21 The players in Aspergillus genomics Aspergillus nidulans Aspergillus fumigatus –Neosartorya clade –Aspergillus fumigatus group –Aspergillus section Fumigati Aspergillus oryzae

22 Geiser, D.M. Frisvad, J. Taylor, J.W. Mycologia,1998 Beta-tubulin + rodA hydrophobin heterothallic

23 Geiser, D.M. Frisvad, J. Taylor, J.W. Mycologia 1998 Beta-tubulin + rodA hydrophobin

24 Geiser, D.M. Frisvad, J. Taylor, J.W. Mycologia 1998 Beta-tubulin + rodA hydrophobin

25 Evolution in Aspergillus fumigatus group Monophyletic A. fumigatus and N. fischeri are close relatives Heterothallism derived? Secondary metabolite data contrasts with benA/rodA phylogeny Pringle, Taylor and others: asking the question whether its asexual

26 The players in Aspergillus genomics Aspergillus nidulans Aspergillus fumigatus Aspergillus oryzae –Petromyces clade –Aspergillus flavus group –Aspergillus Section Circumdati

27 A. flavus, A. oryzae, A. niger and relatives (Petromyces) NJ analysis of Steve Petersons 25S data

28 Geiser, DM Pitt, JI Taylor JW PNAS 1998

29 Geiser, DM Horn, BW Dorner, JW Taylor JW FG&B 2001

30 Using evolution to do good genomics Comparative genomics IS evolutionary biology Conservation of function is an adaptive process Clark et al Inferring non-neutral evolution from human-chimp-mouse orthologous gene trios. Science 302;

31 The future Genomics helps traditional evolutionary biologists to do their jobs because it provides tools Understanding how genes evolve provides a framework for thinking about how they might function


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