Mating-type genes and sexual potential in the ascomycete genera Aspergillus and Penicillium

Eagle, C. (2009) Mating-type genes and sexual potential in the ascomycete genera Aspergillus and Penicillium. PhD thesis, University of Nottingham.

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Abstract

Mating-type and other ‘sex-related’ genes in the filamentous ascomcyete genera Aspergillus and Penicillium, were examined to investigate the potential sexual capacity of supposedly asexual species and also the possible evolutionary route and ancestry of mating strategy and mating-type genes.

Two heterothallic and one homothallic sexual species were screened to determine the presence and genomic organisation of mating-type genes. An additional gene has previously been detected in Neosartorya fischeri, N. fumigata and Penicillium marneffei. This gene was also detected and sequenced in the heterothallic species, Emericella heterothallica and the homothallic species, Eurotium repens. The expression of this gene was investigated under conditions that cause expression of mating-type genes in these species.

Mating-type and other ‘sex-related’ genes were investigated in asexual Aspergilli that have been genome sequenced. Expression of mating-type, α-factor pheromone precursor, pheromone receptor and two transcription factor encoding genes were also investigated. Gene expression varied between species, but no genes displayed mating type-dependent expression.

Previous studies had developed a degenerate PCR diagnostic approach to identify putative MAT1-1-1 and MAT1-2-1 gene fragments. This degenerate PCR diagnostic was performed on Penicillium species in the subgenus Penicillium to determine the presence or absence of mating-type genes. Mating-type gene fragments or whole open reading frames were sequenced from four of these Penicillium species. RT-PCR analyses were also performed on these species, and MAT1-1-1 and MAT1-2-1 gene expression was confirmed in three of the four Penicillium species.

The overall structure of the mating-type loci and idiomorphs of the Aspergillus and Penicillium species revealed certain common features. The ancestral mating strategy of the Eurotiomycetes has been suggested to be homothallism. Whilst this remains possible, alternative evolutionary scenarios are suggested from this investigation.

Item Type:Thesis (PhD)
Supervisors:Dyer, P.S.
Uncontrolled Keywords:Fungal genetics, Fungal reproduction, Asexual reproduction, Mating strategy
Faculties/Schools:UK Campuses > Faculty of Medicine and Health Sciences > School of Biology
ID Code:905
Deposited By:Dr C Eagle
Deposited On:13 May 2010 13:36
Last Modified:13 May 2010 13:36

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