Dataset Information

Origin and evolution of carnivorism in the Ascomycota (fungi).

ABSTRACT: Carnivorism is one of the basic life strategies of fungi. Carnivorous fungi possess the ability to trap and digest their preys by sophisticated trapping devices. However, the origin and development of fungal carnivorism remains a gap in evolution biology. In this study, five protein-encoding genes were used to construct the phylogeny of the carnivorous fungi in the phylum Ascomycota; these fungi prey on nematodes by means of specialized trapping structures such as constricting rings and adhesive traps. Our analysis revealed a definitive pattern of evolutionary development for these trapping structures. Molecular clock calibration based on two fossil records revealed that fungal carnivorism diverged from saprophytism about 419 Mya, which was after the origin of nematodes about 550-600 Mya. Active carnivorism (fungi with constricting rings) and passive carnivorism (fungi with adhesive traps) diverged from each other around 246 Mya, shortly after the occurrence of the Permian-Triassic extinction event about 251.4 Mya. The major adhesive traps evolved around 198-208 Mya, which was within the time frame of the Triassic-Jurassic extinction event about 201.4 Mya. However, no major carnivorous ascomycetes divergence was correlated to the Cretaceous-Tertiary extinction event, which occurred more recently (about 65.5 Mya). Therefore, a causal relationship between mass extinction events and fungal carnivorism evolution is not validated in this study. More evidence including additional fossil records is needed to establish if fungal carnivorism evolution was a response to mass extinction events.

SUBMITTER: Yang E

PROVIDER: S-EPMC3390824 | biostudies-literature | 2012 Jul

REPOSITORIES: biostudies-literature

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Origin and evolution of carnivorism in the Ascomycota (fungi).

Yang Ence E Xu Lingling L Yang Ying Y Zhang Xinyu X Xiang Meichun M Wang Chengshu C An Zhiqiang Z Liu Xingzhong X

Proceedings of the National Academy of Sciences of the United States of America 20120619 27

Carnivorism is one of the basic life strategies of fungi. Carnivorous fungi possess the ability to trap and digest their preys by sophisticated trapping devices. However, the origin and development of fungal carnivorism remains a gap in evolution biology. In this study, five protein-encoding genes were used to construct the phylogeny of the carnivorous fungi in the phylum Ascomycota; these fungi prey on nematodes by means of specialized trapping structures such as constricting rings and adhesive ...[more]

PMID: 22715289

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Project description:BackgroundThe evolution of multicellularity is accompanied by the occurrence of differentiated tissues, of organismal developmental programs, and of mechanisms keeping the balance between proliferation and differentiation. Initially, the SET-domain proteins were associated exclusively with regulation of developmental genes in metazoa. However, finding of SET-domain genes in the unicellular yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe suggested that SET-domain proteins regulate a much broader variety of biological programs. Intuitively, it is expected that the numbers, types, and biochemical specificity of SET-domain proteins of multicellular versus unicellular forms would reflect the differences in their biology. However, comparisons across the unicellular and multicellular domains of life are complicated by the lack of knowledge of the ancestral SET-domain genes. Even within the crown group, different biological systems might use the epigenetic 'code' differently, adapting it to organism-specific needs. Simplifying the model, we undertook a systematic phylogenetic analysis of one monophyletic fungal group (Ascomycetes) containing unicellular yeasts, Saccharomycotina (hemiascomycetes), and a filamentous fungal group, Pezizomycotina (euascomycetes).ResultsSystematic analysis of the SET-domain genes across an entire eukaryotic phylum has outlined clear distinctions in the SET-domain gene collections in the unicellular and in the multicellular (filamentous) relatives; diversification of SET-domain gene families has increased further with the expansion and elaboration of multicellularity in animal and plant systems. We found several ascomycota-specific SET-domain gene groups; each was unique to either Saccharomycotina or Pezizomycotina fungi. Our analysis revealed that the numbers and types of SET-domain genes in the Saccharomycotina did not reflect the habitats, pathogenicity, mechanisms of sexuality, or the ability to undergo morphogenic transformations. However, novel genes have appeared for functions associated with the transition to multicellularity. Descendents of most of the SET-domain gene families found in the filamentous fungi could be traced in the genomes of extant animals and plants, albeit as more complex structural forms.ConclusionSET-domain genes found in the filamentous species but absent from the unicellular sister group reflect two alternative evolutionary events: deletion from the yeast genomes or appearance of novel structures in filamentous fungal groups. There were no Ascomycota-specific SET-domain gene families (i.e., absent from animal and plant genomes); however, plants and animals share SET-domain gene subfamilies that do not exist in the fungi. Phylogenetic and gene-structure analyses defined several animal and plant SET-domain genes as sister groups while those of fungal origin were basal to them. Plants and animals also share SET-domain subfamilies that do not exist in fungi.

Project description:BackgroundRNA secondary structure is highly conserved throughout evolution. The higher order structure is fundamental in establishing important structure-function relationships. Nucleotide sequences from ribosomal RNA (rRNA) genes have made a great contribution to our understanding of Ascomycota phylogeny. However, filling the gaps between molecular phylogeny and morphological assumptions based on ascus dehiscence modes and type of fruitbodies at the higher level classification of the phylum remains an unfulfilled task faced by mycologists.Methodology/principal findingsWe selected some major groups of Ascomycota to view their phylogenetic relationships based on analyses of rRNA secondary structure. Using rRNA secondary structural information, here, we converted nucleotide sequences into the structure ones over a 20-symbol code. Our structural analyses together with ancestral character state reconstruction produced reasonable phylogenetic position for the class Geoglossomycetes as opposed to the classic nucleotide analyses. Judging from the secondary structure analyses with consideration of mode of ascus dehiscence and the ability of forming fruitbodies, we draw a clear picture of a possible evolutionary route for fungal asci and some major groups of fungi in Ascomycota. The secondary structure trees show a more reasonable phylogenetic position for the class Geoglossomycetes.ConclusionsOur results illustrate that asci lacking of any dehiscence mechanism represent the most primitive type. Passing through the operculate and Orbilia-type asci, bitunicate asci occurred. The evolution came to the most advanced inoperculate type. The ascus-producing fungi might be derived from groups lacking of the capacity to form fruitbodies, and then evolved multiple times. The apothecial type of fruitbodies represents the ancestral state, and the ostiolar type is advanced. The class Geoglossomycetes is closely related to Leotiomycetes and Sordariomycetes having a similar ascus type other than it was originally placed based on nucleotide sequence analyses.

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Project description:Cercosporoid fungi (Mycosphaerellaceae, Mycosphaerellales, Ascomycota) are one of the largest and most diverse groups of hyphomycetes causing a wide range of diseases of economically important plants as well as of plants in the wild. Although more than 6000 species are known for this group, the documentation of this fungal group is far from complete. Especially in the tropics, the diversity of cercosporoid fungi is poorly known. The present study aims to identify and characterise cercosporoid fungi collected on host plants belonging to Fabaceae in Benin, West Africa. Information on their morphology, host species and DNA sequence data (18S rDNA, 28S rDNA, ITS and tef1) is provided. DNA sequence data were obtained by a simple and non-culture-based method for DNA isolation which has been applied for cercosporoid fungi for the first time in the context of the present study. Among the loci used for the phylogenetic analysis, tef1 provided the best resolution together with the multigene dataset. Species delimitation in many cases, however, was only possible by combining molecular sequence data with morphological characteristics. Based on forty specimens recently collected in Benin, 18 species are presented with morphological descriptions, illustrations and sequence data. Among these, six species in the genus Cercospora and two species in Pseudocercospora are proposed as species new to science. The newly described species are Cercospora (C.) beninensis on Crotalaria macrocalyx, C. parakouensis on Desmodium tortuosum, C. rhynchophora on Vigna unguiculata, C. vignae-subterraneae on Vigna subterranea, C. tentaculifera on Vigna unguiculata, C. zorniicola on Zornia glochidiata, Pseudocercospora sennicola on Senna occidentalis and Pseudocercospora tabei on Vigna unguiculata. Eight species of cercosporoid fungi are reported for Benin for the first time, three of them, namely C. cf. canscorina, C. cf. fagopyri and C. phaseoli-lunati are new for West Africa. The presence of two species of cercosporoid fungi on Fabaceae previously reported from Benin, namely Nothopassalora personata and Passalora arachidicola, is confirmed.

Dataset Information

Origin and evolution of carnivorism in the Ascomycota (fungi).

Publications

Origin and evolution of carnivorism in the Ascomycota (fungi).

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