A phylogenetic analysis of Greek isolates of Aspergillus species based on morphology and nuclear and mitochondrial gene sequences.

Antonios Krimitzas,Vassili N Kouvelis,Evangelia Kapsanaki-Gotsi,Milton A Typas,Ioanna Pyrri

doi:10.1155/2013/260395

Antonios Krimitzas, Vassili N Kouvelis + Show 3 more

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https://doi.org/10.1155/2013/260395

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Abstract

Aspergillus species originating from Greece were examined by morphological and molecular criteria to explore the diversity of this genus. The phylogenetic relationships of these species were determined using sequences from the ITS and IGS region of the nuclear rRNA gene complex, two nuclear genes (β-tubulin (benA) and RNA polymerase II second largest subunit (rpb2)) and two mitochondrial genes (small rRNA subunit (rns) and cytochrome oxidase subunit I (cox1)) and, where available, related sequences from databases. The morphological characters of the anamorphs and teleomorphs, and the single gene phylogenetic trees, differentiated and placed the species examined in the well-supported sections of Aenei, Aspergillus, Bispori, Candidi, Circumdati, Clavati, Cremei, Flavi, Flavipedes, Fumigati, Nidulantes, Nigri, Restricti, Terrei, Usti, and Zonati, with few uncertainties. The combined use of the three commonly employed nuclear genes (benA, rpb2, and ITS), the IGS region, and two less often used mitochondrial gene sequences (rns and cox1) as a single unit resolved several taxonomic ambiguities. A phylogenetic tree was inferred using Neighbour-Joining, Maximum Parsimony, and Bayesian methods. The strains examined formed seven well-supported clades within the genus Aspergillus. Altogether, the concatenated nuclear and mitochondrial sequences offer additional tools for an improved understanding of phylogenetic relationships within this genus.

Highlights

The genus Aspergillus is one of the most common and important genera of microfungi
The cultural characteristics of the Aspergillus spp. have been recorded for all the strains and their evaluation was critical in cases of closely related species
Studies based on a single gene do not always faithfully represent the history of the entire genome containing it and comparisons may give the wrong conclusions about the relationship of a fungus with members of the same species or even the same genus [44]

Summary

Introduction

The genus Aspergillus is one of the most common and important genera of microfungi. Several species of the genus proved very useful cell factories for biotechnology purposes since they produce organic acids, extracellular enzymes, nutraceuticals (isoprenoids), and aroma compounds and are capable of fermenting various substrates under extreme cultivation conditions, usually intolerable to bacteria and yeasts [1,2,3,4]. The genus contains a number of species that produce toxic metabolites, act as opportunistic pathogens to humans, or decompose a wide variety of substrates [5, 6]. Their high diversity combined with the worldwide distribution necessitates the detailed taxonomic and phylogenetic study of Aspergillus species in order to provide more appropriate tools for their accurate and fast identification. The first most comprehensive taxonomic treatise of the genus was based on morphological criteria and included 150 taxa that were separated in “groups” [7] These clusters of species (“groups”) were later revised to 18 “sections” in 6 subgenera, in order to receive nomenclatural status [8]. A list of 182 species valid names was compiled [9], and expanded to ∼250 species [3], and it is expected to increase further as new species are discovered and speciation concepts are refined [10]

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