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Evolution of the Aspergilli : stuff for genomicists to think about. David M. Geiser Penn State University, USA dgeiser@psu.edu. Aspergillus evolution. What is Aspergillus ? The major players in the genus and how are they related Interesting comparative questions about Aspergillus

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Evolution of the Aspergilli : stuff for genomicists to think about


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evolution of the aspergilli stuff for genomicists to think about

Evolution of the Aspergilli:stuff for genomicists to think about

David M. Geiser

Penn State University, USA

dgeiser@psu.edu

aspergillus evolution
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
what is aspergillus
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)
aspergillus is a eurotiomycete
Aspergillus is a Eurotiomycete

18S rDNA

Geiser and

Lo Buglio

2001

eurotiomycetes
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
conidiation in the plectomycetes
Conidiation in the Plectomycetes
  • thallic (T): Onygenales, Ascosphaerales
  • blastic (B): Eurotiales

T

biseriate

B

T

B

T

B

B

uniseriate

Geiser and LoBuglio 2001

ascomatal types in the eurotiomycetes
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)

Trichocoma

Eupenicillium

Emericella

Petromyces

C/S

C/S

C/S

Gymnoascus

Onygena

S

S

Monascus

Byssochlamys

Ascosphaera

Eurotium

C

nutriocyte

C

C

N

Geiser and LoBuglio 2001

sexual stages associated phylogenetically with important aspergillus spp
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.
aspergillus phylogenetics
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…
aspergillus monophyletic

18S rDNA

Aspergillus -- monophyletic?

Tamura, M.

Kawahara, K.

Sugiyama, J.

2000.

aspergillus 25s rdna tree
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
slide13

Petromyces

sexual stage

multiloculate

stroma

Emericella sexual stage

cleistothecium surrounded

by hülle cells (stroma)

Eurotium sexual stage

cleistothecium, no

stroma

Sclerocleista

Warcupiella

Neosartorya sexual stage

cleistothecium composed

of cottony hyphae

Fennellia sexual stage

Chaetosartorya sexual stage

slide14

Subgenus

Circumdati:

Association with

plants,seeds

psychrotolerance

Xerophilicty/tolerance

heat-resistant ascospores

Thermotolerance

heat-resistant ascospores

the players in aspergillus genomics
The players in Aspergillus genomics
  • Aspergillus nidulans
    • “Emericella clade”
    • Aspergillus nidulans group
    • Aspergillus section Nidulantes
  • Aspergillus fumigatus
  • Aspergillus oryzae
emericella clade
Emericella clade

NJ analysis of Steve Peterson’s 25S data

  • A. nidulans
  • A. sydowii - coral pathogen
  • Hülle cells
  • Homothallics
  • Putative asexuals
  • Heterothallic
aspergillosis of sea fan corals
Aspergillosis of sea fan corals

Aspergillus sydowii

in culture: a relative of

A. nidulans!

Geiser, D.M.

Ritchie, K.

Smith, G.

Taylor, J.W.

Nature, 1998

Kiho Kim

Aspergillosis of sea fan coral

sexual versus asexual strategies
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!
the players in aspergillus genomics1
The players in Aspergillus genomics
  • Aspergillus nidulans
  • Aspergillus fumigatus
    • Neosartorya clade
    • Aspergillus fumigatus group
    • Aspergillus section Fumigati
  • Aspergillus oryzae
slide22

Geiser, D.M.

Frisvad, J.

Taylor, J.W.

Mycologia,1998

Beta-tubulin +

rodA hydrophobin

heterothallic

heterothallic

slide23

Geiser, D.M.

Frisvad, J.

Taylor, J.W.

Mycologia 1998

Beta-tubulin +

rodA hydrophobin

slide24

Geiser, D.M.

Frisvad, J.

Taylor, J.W.

Mycologia 1998

Beta-tubulin +

rodA hydrophobin

evolution in aspergillus fumigatus group
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 it’s asexual
the players in aspergillus genomics2
The players in Aspergillus genomics
  • Aspergillus nidulans
  • Aspergillus fumigatus
  • Aspergillus oryzae
    • Petromyces clade
    • Aspergillus flavus group
    • Aspergillus Section Circumdati
slide27

A.flavus, A. oryzae, A. niger

and relatives (Petromyces)

NJ analysis of Steve Peterson’s 25S data

slide28

Geiser, DM

Pitt, JI

Taylor JW

PNAS

1998

slide29

Geiser, DM

Horn, BW

Dorner, JW

Taylor JW

FG&B

2001

using evolution to do good genomics
Using evolution to do good genomics
  • Comparative genomics IS evolutionary biology
  • Conservation of function is an adaptive process
  • Clark et al. 2003. Inferring non-neutral evolution from human-chimp-mouse orthologous gene trios. Science 302; 1960-62.
the future
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