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McTaggart AR, James TY, Shivas RG, Drenth A, Wingfield BD, Summerell BA, Duong TA. Population genomics reveals historical and ongoing recombination in the Fusarium oxysporum species complex. Stud Mycol 2022; 99:100132. [PMID: 35027981 PMCID: PMC8693468 DOI: 10.1016/j.simyco.2021.100132] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The Fusarium oxysporum species complex (FOSC) is a group of closely related plant pathogens long-considered strictly clonal, as sexual stages have never been recorded. Several studies have questioned whether recombination occurs in FOSC, and if it occurs its nature and frequency are unknown. We analysed 410 assembled genomes to answer whether FOSC diversified by occasional sexual reproduction interspersed with numerous cycles of asexual reproduction akin to a model of predominant clonal evolution (PCE). We tested the hypothesis that sexual reproduction occurred in the evolutionary history of FOSC by examining the distribution of idiomorphs at the mating locus, phylogenetic conflict and independent measures of recombination from genome-wide SNPs and genes. A phylogenomic dataset of 40 single copy orthologs was used to define structure a priori within FOSC based on genealogical concordance. Recombination within FOSC was tested using the pairwise homoplasy index and divergence ages were estimated by molecular dating. We called SNPs from assembled genomes using a k-mer approach and tested for significant linkage disequilibrium as an indication of PCE. We clone-corrected and tested whether SNPs were randomly associated as an indication of recombination. Our analyses provide evidence for sexual or parasexual reproduction within, but not between, clades of FOSC that diversified from a most recent common ancestor about 500 000 years ago. There was no evidence of substructure based on geography or host that might indicate how clades diversified. Competing evolutionary hypotheses for FOSC are discussed in the context of our results.
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Affiliation(s)
- A R McTaggart
- Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Ecosciences Precinct, Dutton Park, 4102, Queensland, Australia
| | - T Y James
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, 48109, USA
| | - R G Shivas
- Centre for Crop Health, Institute for Life Sciences and the Environment, University of Southern Queensland, Toowoomba, 4350, Australia
| | - A Drenth
- Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Ecosciences Precinct, Dutton Park, 4102, Queensland, Australia
| | - B D Wingfield
- Department of Biochemistry, Genetics and Microbiology, Tree Protection Co-operative Programme (TPCP), Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, South Africa
| | - B A Summerell
- Australian Institute of Botanical Science, Royal Botanic Gardens & Domain Trust, Sydney, Australia
| | - T A Duong
- Department of Biochemistry, Genetics and Microbiology, Tree Protection Co-operative Programme (TPCP), Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, South Africa
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Microeukaryotic Communities on the Fruit of Gardenia thunbergia Thunb. with a Focus on Pathogenic Fungi. Pathogens 2021; 10:pathogens10050555. [PMID: 34064327 PMCID: PMC8147784 DOI: 10.3390/pathogens10050555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 04/27/2021] [Accepted: 04/30/2021] [Indexed: 11/24/2022] Open
Abstract
Woody fruit which stay on ornamental plants for a long time may present a risk of infection to other organisms due to the presence of pathogens on their surface. We compared the microbe communities on the fruit surfaces of garden ornamental Gardenia thunbergia Thunb. with those on other surfaces in the study region. As Gardenia fruit contain antifungal substances, the focus of this study was on the fungal communities that exist thereon. We used Illumina sequencing to identify Amplicon Sequence Variants (ASV) of the internal transcribed spacer 2 (ITS2) of the ribosomal RNA. The microbial communities of the Gardenia fruit are distinct from the communities from the surrounding environments, indicating a specialized microhabitat. We employed clustering methods to position unidentified ASVs relative to known ASVs. We identified a total of 56 ASVs representing high risk fungal species as putative plant pathogens exclusively found on the fruit of Gardenia. Additionally, we found several ASVs representing putative animal or human pathogens. Those pathogens were distributed over distinct fungi clades. The infection risk of the high diversity of putative pathogens represented on the Gardenia fruit needs to be elucidated in further investigations.
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Draft Genome Sequences of Alternaria Strains Isolated from Grapes and Apples. Microbiol Resour Announc 2020; 9:9/14/e01491-19. [PMID: 32241865 PMCID: PMC7118191 DOI: 10.1128/mra.01491-19] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Here, we report the draft genome sequences of Alternaria alternata, isolated from seedless grapes, and Alternaria arborescens and Alternaria atra, isolated from Red Delicious apples, all from the Washington, DC, area.
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