Discovery of a sexual cycle in Aspergillus clavatus
Keywords:Cleistothecium, Ascospore, Aspergillus clavatus
Background and objective: Aspergillus clavatus is an opportunistic human pathogen causing invasive aspergillosis. It is an economically important species because it can grow on rotting fruit (apples) and stored food products and able to produce a variety of mycotoxins. It has only been known to reproduce mitotically. This study aimed to discover the sexual reproduction in A. clavatus.
Methods: Identifying mating-type (MAT1-1 or MAT1-2) using PCR of 20 worldwide clinical and environmental isolates, crossing isolates on oatmeal agar in darkness with plate sealing, Recombination in ascospore offspring was demonstrated using molecular markers.
Results: There were similar ratios of the two mating types (45% MAT1-1 n = 9, 55% MAT1-2 n = 11). A. clavatus possesses a functional sexual cycle with mature cleistothecia fawn to brown/yellow in color, containing heat-resistant ascospores, produced after four weeks incubation at 25˚C and 28˚C on Nescofilm- sealed oatmeal agar plates. The cleistothecia contain hyaline ascospores that have two equatorial ridges. Recombination, leading to increased genotypic variation demonstrated in the ascospore offspring using molecular markers.
Conclusion: The ability of A. clavatus to undergo sexual reproduction is highly significant in understanding the biology and evolution of the species. The presence of a sexual cycle provides an invaluable tool for classical genetic analysis and will facilitate research into the genetic basis of pathogenicity and fungicide resistance.
Varga J, Frisvad JC, Samson RA. Taxonomic revision of Aspergillus section Clavati based on molecular, morphological and physiological data. Stud Mycol 2007; 59:89–106.
Fliege R, Metzler M. Electrophilic properties of patulin. Adduct structures and reaction pathways with 4-bromothiophenol and other model nucleophiles. Chem Res Toxicol 2000; 13:363–72.
McKenzie RA, Kelly MA, Shivas RG, Gibson JA, Cook PJ, Widderick K, et al. Aspergillus clavatus tremorgenic neurotoxicosis in cattle fed sprouted grains. Austalian Vet J 2004; 82:635–8.
Nesci A, Morales M, Etcheverry M. Interrelation of growth media and water activity in sclerotia characteristics of Aspergillus section Flavi. Lett Appl Microbiol 2007; 44(2):149–54.
Pierrotti LC, Baddour LM. Fungal endocarditis, 1995-2000. Chest 2002; 122;302–10.
Varga J, Rigo K, Molnar J, Toth B, Szencz S, Teren J, et al. Mycotoxin production and evolutionary relationships among species of Aspergillus section Clavati. Antonie Van Leeuwenhoek 2003; 83:91–200.
Loretti AP, Colodel EM, Driemeier D, Correa AM, Bangel JJ, Ferreiro L. Neurological disorder in dairy cattle associated with consumption of beer residues contaminated with Aspergillus clavatus. J Vet Diagn Invest 2003; 15(2):123–32.
McKee DH, Cooper PN, Denning DW. Invasive aspergillosis in a patient with MELAS syndrome. J Neurol Neurosurg Psychiatry 2000; 68(6):765–7.
Loretti AP, Colodel EM, Driemeier D, Correa AM, Bangel J, Ferreiro L. Neurological disorder in dairy cattle associated with consumption of beer residues contaminated with Aspergillus clavatus. J Vet Diagn Invest 2003; 15(2):123–32.
Blyth W, Hardy J. Mutagenic and tumourigenic properties of the spores of Aspergillus clavatus. Br J Cancer 1982; 45:105–17.
Scudamore KA, Livesey TC. Occurrence and Signiücance of Mycotoxins in Forage Crops and Silage: a Review. J Sci Food Agric 1998; 77:1–17
Matumba L, Monjerezi M, Khonga E, Lakudzala D. Aflatoxins in sorghum, sorghum malt and traditional opaque beer in southern Malawi. Food Control 2011; 22:266–9.
Samson RA, Hong S, Peterson SW, Frisvad JC, Varga J. Polyphasic taxonomy of Aspergillus section Fumigati and its teleomorph Neosartorya. Stud Mycol 2007; 59:147–203.
Udagawa Si, Uchiyama. Neocarpenteles: A new ascomycete genus to accommodate Hemicarpenteles acanthosporus. Mycoscience 2002; 43(1):3–6.
Nierman WC, May G, Kim HS, Anderson M J, Chen D, Denning DW.What the Aspergillus genomes have told us. Med Mycol 2005; 43:S3–5.
Eagle C E. Mating-type genes and sexual potential in the Ascomycete genera Aspergillus and Penicillium. University of Nottingham. PhD thesis; 2009.
Dyer PS, O'Gorman CM. Sexual development and cryptic sexuality in fungi: insights from Aspergillus species. FEMS Microbiol Rev 2011; 36(1):165-92.
Paoletti M, Rydholm C, Schwier EU, Anderson MJ, Szakacs G, Lutzoni F, et al. Evidence for sexuality in the opportunistic fungal pathogen Aspergillus fumigatus. Curr Biol 2005; 15:1242–8.
O'Gorman C M, Fuller H, Dyer PS. Discovery of a sexual cycle in the opportunistic fungal pathogen Aspergillus fumigatus. Nature 2009; 457:471–4.
Robert V, Groenewald M, Epping W, Boekhout T, Smith M, Poot G, et al. CBS Yeasts Database, The Netherlands, Centraalbureau voor Schimmelcultures, Utrecht; 2007.
Murtagh GJ, Dyer PS, McClure PC, Crittenden PD. Use of randomly amplified polymorphic DNA markers as a tool to study variation in lichen-forming fungi. Lichenologist 1999; 31: 257–67.
Fisher RA. Statistical Methods for Research Workers. 7th edition. Oliver and Boyd, Edinburgh, Scotland; 1938.
Peterson SW. Integration of Modern Taxonomic Methods for Penicillium and Aspergillus Classification. Amsterdam. Chapter in book Phylogenetic relationships in Aspergillus based on rDNA sequence analysis. In: Samson RA, Pitt JI editor Harwood Academic Publishers; 2000. p. 323–55.
Yaguchi T, Someya A, Miyadoh S, Udagawa S. Aspergillus ingratus, a new species in Aspergillus section Clavati.Trans. Mycol Soc Jpn 1993; 34:305–10.
Tamura M, Hamamoto M, Canete-Gibas CF, Sugiyama J, Nakase T. Genetic relatedness among species in Aspergillus section Clavati as measured by electrophoretic comparison of enzymes, DNA base composition, and DNA-DNA hybridization. Gen Appl Microbiol 1999; 45(2):77–83.
Peterson SW. Neosartorya pseudofischeri sp. nov. and its relation -ship to other species in Aspergillus section fumigati. Mycol Res 1992; 96:547–54.
Horn BW, Moore GG, Carbone I. Sexual reproduction in Aspergillus flavus. Mycologia 2009; 101(3):423–9.
Dyer PS, O'Gorman CM. A fungal sexual revolution: Aspergillus and Penicillium show the way. Curr Opin Microbiol 2011; 14:649–54.
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