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Belov AA, Witte TE, Overy DP, Smith ML. Transcriptome analysis implicates secondary metabolite production, redox reactions, and programmed cell death during allorecognition in Cryphonectria parasitica. G3-GENES GENOMES GENETICS 2021; 11:6025178. [PMID: 33561228 PMCID: PMC7849911 DOI: 10.1093/g3journal/jkaa021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 11/16/2020] [Indexed: 02/04/2023]
Abstract
The underlying molecular mechanisms of programmed cell death associated with fungal allorecognition, a form of innate immunity, remain largely unknown. In this study, transcriptome analysis was used to infer mechanisms activated during barrage formation in vic3-incompatible strains of Cryphonectria parasitica, the chestnut blight fungus. Pronounced differential expression occurred in barraging strains of genes involved in mating pheromone (mf2-1, mf2-2), secondary metabolite production, detoxification (including oxidative stress), apoptosis-related, RNA interference, and HET-domain genes. Evidence for secondary metabolite production and reactive oxygen species (ROS) accumulation is supported through UPLC-HRMS analysis and cytological staining, respectively. Differential expression of mating-related genes and HET-domain genes was further examined by RT-qPCR of incompatible interactions involving each of the six vegetative incompatibility (vic) loci in C. parasitica and revealed distinct recognition process networks. We infer that vegetative incompatibility in C. parasitica activates defence reactions that involve secondary metabolism, resulting in increased toxicity of the extra- and intracellular environment. Accumulation of ROS (and other potential toxins) may result in detoxification failure and activation of apoptosis, sporulation, and the expression of associated pheromone genes. The incompatible reaction leaves abundant traces of a process-specific metabolome as conidiation is initiated.
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Affiliation(s)
- Anatoly A Belov
- Department of Biology, Carleton University, Ottawa, ON K1S 5B6, Canada
| | - Thomas E Witte
- Department of Biology, Carleton University, Ottawa, ON K1S 5B6, Canada
| | - David P Overy
- Agriculture and Agri-Food Canada, Ottawa, ON, K1Y 4X2, Canada
| | - Myron L Smith
- Department of Biology, Carleton University, Ottawa, ON K1S 5B6, Canada
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Crouch JA, Dawe A, Aerts A, Barry K, Churchill ACL, Grimwood J, Hillman BI, Milgroom MG, Pangilinan J, Smith M, Salamov A, Schmutz J, Yadav JS, Grigoriev IV, Nuss DL. Genome Sequence of the Chestnut Blight Fungus Cryphonectria parasitica EP155: A Fundamental Resource for an Archetypical Invasive Plant Pathogen. PHYTOPATHOLOGY 2020; 110:1180-1188. [PMID: 32207662 DOI: 10.1094/phyto-12-19-0478-a] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Cryphonectria parasitica is the causal agent of chestnut blight, a fungal disease that almost entirely eliminated mature American chestnut from North America over a 50-year period. Here, we formally report the genome of C. parasitica EP155 using a Sanger shotgun sequencing approach. After finishing and integration with simple-sequence repeat markers, the assembly was 43.8 Mb in 26 scaffolds (L50 = 5; N50 = 4.0Mb). Eight chromosomes are predicted: five scaffolds have two telomeres and six scaffolds have one telomere sequence. In total, 11,609 gene models were predicted, of which 85% show similarities to other proteins. This genome resource has already increased the utility of a fundamental plant pathogen experimental system through new understanding of the fungal vegetative incompatibility system, with significant implications for enhancing mycovirus-based biological control.
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Affiliation(s)
- Jo Anne Crouch
- Mycology and Nematology Genetic Diversity and Biology Laboratory, United States Department of Agriculture-Agricultural Research Service, 10300 Baltimore Avenue, Building 010A, Beltsville, MD, U.S.A
| | - Angus Dawe
- Department of Biological Sciences, Mississippi State University, 295 Lee Boulevard, Mississippi State, MS, U.S.A
| | - Andrea Aerts
- United States Department of Energy Joint Genome Institute, Walnut Creek, CA, U.S.A
| | - Kerrie Barry
- United States Department of Energy Joint Genome Institute, Walnut Creek, CA, U.S.A
| | - Alice C L Churchill
- School of Integrative Plant Science, Plant Pathology and Plant-Microbe Biology Section, Cornell University, Ithaca, NY, U.S.A
| | - Jane Grimwood
- HudsonAlpha Institute for Biotechnology, Huntsville, AL, U.S.A
| | - Bradley I Hillman
- Department of Plant Biology, Rutgers University, 59 Dudley Road, New Brunswick, NJ, U.S.A
| | - Michael G Milgroom
- School of Integrative Plant Science, Plant Pathology and Plant-Microbe Biology Section, Cornell University, Ithaca, NY, U.S.A
| | - Jasmyn Pangilinan
- United States Department of Energy Joint Genome Institute, Walnut Creek, CA, U.S.A
| | - Myron Smith
- Department of Biology, Carleton University, 1125 Colonel by Drive, Ottawa, ON, Canada
| | - Asaf Salamov
- United States Department of Energy Joint Genome Institute, Walnut Creek, CA, U.S.A
| | - Jeremy Schmutz
- United States Department of Energy Joint Genome Institute, Walnut Creek, CA, U.S.A
- HudsonAlpha Institute for Biotechnology, Huntsville, AL, U.S.A
| | - Jagjit S Yadav
- Environmental Genetics and Molecular Toxicology Division, Department of Environmental Health, University of Cincinnati College of Medicine, Cincinnati, OH, U.S.A
| | - Igor V Grigoriev
- HudsonAlpha Institute for Biotechnology, Huntsville, AL, U.S.A
- Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, CA, U.S.A
| | - Donald L Nuss
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD, U.S.A
- Division of Plant and Soil Sciences, West Virginia University, Morgantown, WV, U.S.A
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Proteomic investigation of interhyphal interactions between strains of Agaricus bisporus. Fungal Biol 2020; 124:579-591. [PMID: 32448449 DOI: 10.1016/j.funbio.2020.02.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 02/17/2020] [Accepted: 02/19/2020] [Indexed: 11/23/2022]
Abstract
Hyphae of filamentous fungi undergo polar extension, bifurcation and hyphal fusion to form reticulating networks of mycelia. Hyphal fusion or anastomosis, a ubiquitous process among filamentous fungi, is a vital strategy for how fungi expand over their substrate and interact with or recognise self- and non-self hyphae of neighbouring mycelia in their environment. Morphological and genetic characterisation of anastomosis has been studied in many model fungal species, but little is known of the direct proteomic response of two interacting fungal isolates. Agaricus bisporus, the most widely cultivated edible mushroom crop worldwide, was used as an in vitro model to profile the proteomes of interacting cultures. The globally cultivated strain (A15) was paired with two distinct strains; a commercial hybrid strain and a wild isolate strain. Each co-culture presented a different interaction ranging from complete vegetative compatibility (self), lack of interactions, and antagonistic interactions. These incompatible strains are the focus of research into disease-resistance in commercial crops as the spread of intracellular pathogens, namely mycoviruses, is limited by the lack of interhyphal anastomosis. Unique proteomic responses were detected between all co-cultures. An array of cell wall modifying enzymes, plus fungal growth and morphogenesis proteins were found in significantly (P < 0.05) altered abundances. Nitrogen metabolism dominated in the intracellular proteome, with evidence of nitrogen starvation between competing, non-compatible cultures. Changes in key enzymes of A. bisporus morphogenesis were observed, particularly via increased abundance of glucanosyltransferase in competing interactions and certain chitinases in vegetative compatible interactions only. Carbohydrate-active enzyme arsenals are expanded in antagonistic interactions in A. bisporus. Pathways involved in carbohydrate metabolism and genetic information processing were higher in interacting cultures, most notably during self-recognition. New insights into the differential response of interacting strains of A. bisporus will enhance our understanding of potential barriers to viral transmission through vegetative incompatibility. Our results suggest that a differential proteomic response occurs between A. bisporus at strain-level and findings from this work may guide future proteomic investigation of fungal anastomosis.
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Milgroom MG, Smith ML, Drott MT, Nuss DL. Balancing selection at nonself recognition loci in the chestnut blight fungus, Cryphonectria parasitica, demonstrated by trans-species polymorphisms, positive selection, and even allele frequencies. Heredity (Edinb) 2018; 121:511-523. [PMID: 29426879 DOI: 10.1038/s41437-018-0060-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 01/12/2018] [Accepted: 01/15/2018] [Indexed: 11/09/2022] Open
Abstract
Balancing selection has been inferred in diverse organisms for nonself recognition genes, including those involved in immunity, mating compatibility, and vegetative incompatibility. Although selective forces maintaining polymorphisms are known for genes involved in immunity and mating, mechanisms of balancing selection for vegetative incompatibility genes in fungi are being debated. We hypothesized that allorecognition and its consequent inhibition of virus transmission contribute to the maintenance of polymorphisms in vegetative incompatibility loci (vic) in the chestnut blight fungus, Cryphonectria parasitica. Balancing selection was demonstrated at two loci, vic2 and vic6, by trans-species polymorphisms in C. parasitica, C. radicalis, and C. japonica and signatures of positive selection in gene sequences. In addition, more than half (31 of 54) of allele frequency estimates at six vic loci in nine field populations of C. parasitica from Asia and the eastern US were not significantly different from 0.5, as expected at equilibrium for two alleles per locus under balancing selection. At three vic loci, deviations from 0.5 were predicted based on the effects of heteroallelism on virus transmission. Twenty-five of 27 allele frequency estimates were greater than or equal to 0.5 for the allele that confers significantly stronger inhibition of virus transmission at three loci with asymmetric transmission. These results are consistent with the allorecognition hypothesis that vegetative incompatibility genes are under selection because of their role in reducing infection by viruses.
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Affiliation(s)
- Michael G Milgroom
- School of Integrative Plant Science, Plant Pathology and Plant-Microbe Biology Section, Cornell University, Ithaca, NY, 14853, USA.
| | - Myron L Smith
- Department of Biology, Carleton University, Ottawa, ON, K1S 5B6, Canada
| | - Milton T Drott
- School of Integrative Plant Science, Plant Pathology and Plant-Microbe Biology Section, Cornell University, Ithaca, NY, 14853, USA
| | - Donald L Nuss
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD, 20850, USA.,Division of Plant and Soil Sciences, West Virginia University, Morgantown, WV, 26506, USA
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Brasier C, King K, Kirisits T, Orton E, Webber J. High frequency of vegetative incompatibility combined with haploid selfing in the native European ash foliage coloniser Hymenoscyphus albidus. FUNGAL ECOL 2017. [DOI: 10.1016/j.funeco.2017.04.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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Vegetative incompatibility loci with dedicated roles in allorecognition restrict mycovirus transmission in chestnut blight fungus. Genetics 2014; 197:701-14. [PMID: 24690544 DOI: 10.1534/genetics.114.164574] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Vegetative incompatibility (vic), a form of nonself allorecognition, operates widely in filamentous fungi and restricts transmission of virulence-attenuating hypoviruses in the chestnut blight fungus Cryphonectria parasitica. We report here the use of a polymorphism-based comparative genomics approach to complete the molecular identification of the genetically defined C. parasitica vic loci with the identification of vic1 and vic3. The vic1 locus in the C. parasitica reference strain EP155 consists of a polymorphic HET-domain-containing 771-aa ORF designated vic1a-2, which shares 91% identity with the corresponding vic1a-1 allele, and a small (172 aa) idiomorphic DUF1909-domain-containing ORF designated vic1b-2 that is absent at the vic1-1 locus. Gene disruption of either vic1a-2 or vic1b-2 in strain EP155 eliminated restrictions on virus transmission when paired with a vic1 heteroallelic strain; however, only disruption of vic1a-2 abolished the incompatible programmed cell death (PCD) reaction. The vic3 locus of strain EP155 contains two polymorphic ORFs of 599 aa (vic3a-1) and 102 aa (vic3b-1) that shared 46 and 85% aa identity with the corresponding vic3a-2 and vic3b-2 alleles, respectively. Disruption of either vic3a-1 or vic3b-1 resulted in increased virus transmission. However, elimination of PCD required disruption of both vic3a and vic3b. Additional allelic heterogeneity included a sequence inversion and a 8.5-kb insertion containing a LTR retrotransposon sequence and an adjacent HET-domain gene at the vic1 locus and a 7.7-kb sequence deletion associated with a nonfunctional, pseudo vic locus. Combined gene disruption studies formally confirmed restriction of mycovirus transmission by five C. parasitica vic loci and suggested dedicated roles in allorecognition. The relevance of these results to the acquisition and maintenance of vic genes and the potential for manipulation of vic alleles for enhanced mycovirus transmission are discussed.
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Molecular characterization of vegetative incompatibility genes that restrict hypovirus transmission in the chestnut blight fungus Cryphonectria parasitica. Genetics 2011; 190:113-27. [PMID: 22021387 PMCID: PMC3249360 DOI: 10.1534/genetics.111.133983] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Genetic nonself recognition systems such as vegetative incompatibility operate in many filamentous fungi to regulate hyphal fusion between genetically dissimilar individuals and to restrict the spread of virulence-attenuating mycoviruses that have potential for biological control of pathogenic fungi. We report here the use of a comparative genomics approach to identify seven candidate polymorphic genes associated with four vegetative incompatibility (vic) loci of the chestnut blight fungus Cryphonectria parasitica. Disruption of candidate alleles in one of two strains that were heteroallelic at vic2, vic6, or vic7 resulted in enhanced virus transmission, but did not prevent barrage formation associated with mycelial incompatibility. Detailed characterization of the vic6 locus revealed the involvement of nonallelic interactions between two tightly linked genes in barrage formation, heterokaryon formation, and asymmetric, gene-specific influences on virus transmission. The combined results establish molecular identities of genes associated with four C. parasitica vic loci and provide insights into how these recognition factors interact to trigger incompatibility and restrict virus transmission.
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The horizontal transmission of Cryphonectria hypovirus 1 (CHV1) is affected by virus strains. CHINESE SCIENCE BULLETIN-CHINESE 2009. [DOI: 10.1007/s11434-009-0368-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Milgroom MG, Sotirovski K, Spica D, Davis JE, Brewer MT, Milev M, Cortesi P. Clonal population structure of the chestnut blight fungus in expanding ranges in southeastern Europe. Mol Ecol 2008; 17:4446-58. [PMID: 18803594 DOI: 10.1111/j.1365-294x.2008.03927.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Expanding populations are often less genetically diverse at their margins than at the centre of a species' range. Established, older populations of the chestnut blight fungus, Cryphonectria parasitica, are more variable for vegetative compatibility (vc) types than in expanding populations in southeastern Europe where C. parasitica has colonized relatively recently. To test whether vc types represent clones, we genotyped 373 isolates of C. parasitica from southern Italy, Romania, Bulgaria, Macedonia, Greece and Turkey using 11 sequence-characterized amplified region (SCAR) markers. Ten SCAR loci and six vegetative incompatibility (vic) loci were polymorphic in these samples. These populations are clonal by all criteria tested: (i) among 373 isolates, we found only eight multilocus haplotypes, and the same haplotypes were found in multiple countries, sometimes separated in time by as much as 12 years; (ii) the number of haplotypes observed was significantly less than expected under random mating; (iii) populations are in linkage disequilibrium; (iv) the two sets of independent markers, SCARs and vc types, are highly correlated; and (v) sexual structures of C. parasitica were found only in Bulgaria and Romania. One mating type (MAT-1) was found in 98% of the isolates sampled. In contrast, a population in northern Italy, in the central part of the range in Europe, had 12 multilocus haplotypes among 19 isolates. The spread of a few clones could be the result either of founder effect and restricted migration, or these clones have greater fitness than others and spread because they are better adapted to conditions in southeastern Europe.
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Affiliation(s)
- Michael G Milgroom
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, USA.
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