Evolution of asexual and sexual reproduction in the aspergilli
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Published:2018-09-01
Issue:1
Volume:91
Page:37-59
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ISSN:0166-0616
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Container-title:Studies in Mycology
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language:en
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Short-container-title:Studies in Mycology
Author:
Ojeda-López M.,Chen W.,Eagle C.E.,Gutiérrez G.,Jia W.L.,Swilaiman S.S.,Huang Z.,Park H.-S.,Yu J.-H.,Cánovas D.,Dyer P.S.
Abstract
Aspergillus nidulans has long-been used as a model organism to gain insights into the genetic basis of asexual and sexual developmental processes both in other members of the genus Aspergillus, and filamentous fungi in general. Paradigms have been established concerning
the regulatory mechanisms of conidial development. However, recent studies have shown considerable genome divergence in the fungal kingdom, questioning the general applicability of findings from Aspergillus, and certain longstanding evolutionary theories have been questioned. The phylogenetic
distribution of key regulatory elements of asexual reproduction in A. nidulans was investigated in a broad taxonomic range of fungi. This revealed that some proteins were well conserved in the Pezizomycotina (e.g. AbaA, FlbA, FluG, NsdD, MedA, and some velvet proteins),
suggesting similar developmental roles. However, other elements (e.g. BrlA) had a more restricted distribution solely in the Eurotiomycetes, and it appears that the genetic control of sporulation seems to be more complex in the aspergilli than in some other taxonomic groups of
the Pezizomycotina. The evolution of the velvet protein family is discussed based on the history of expansion and contraction events in the early divergent fungi. Heterologous expression of the A. nidulans abaA gene in Monascus ruber failed to induce development of
complete conidiophores as seen in the aspergilli, but did result in increased conidial production. The absence of many components of the asexual developmental pathway from members of the Saccharomycotina supports the hypothesis that differences in the complexity of their spore formation
is due in part to the increased diversity of the sporulation machinery evident in the Pezizomycotina. Investigations were also made into the evolution of sex and sexuality in the aspergilli. MAT loci were identified from the heterothallic Aspergillus (Emericella)
heterothallicus and Aspergillus (Neosartorya) fennelliae and the homothallic Aspergillus pseudoglaucus (=Eurotium repens). A consistent architecture of the MAT locus was seen in these and other heterothallic aspergilli whereas much variation
was seen in the arrangement of MAT loci in homothallic aspergilli. This suggested that it is most likely that the common ancestor of the aspergilli exhibited a heterothallic breeding system. Finally, the supposed prevalence of asexuality in the aspergilli was examined. Investigations
were made using A. clavatus as a representative ‘asexual’ species. It was possible to induce a sexual cycle in A. clavatus given the correct MAT1-1 and MAT1-2 partners and environmental conditions, with recombination confirmed utilising molecular
markers. This indicated that sexual reproduction might be possible in many supposedly asexual aspergilli and beyond, providing general insights into the nature of asexuality in fungi.
Funder
National Natural Science Foundation of China
National Research Foundation of Korea (NRF)
Intelligent Synthetic Biology Center of Global Frontier Projects
Government of Iraq PhD scholarship
Spanish Ministry of Economy and Competitiveness (MINECO
Publisher
Westerdijk Fungal Biodiversity Institute
Subject
Agricultural and Biological Sciences (miscellaneous)
Cited by
116 articles.
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