1
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Hai D, Li J, Jiang D, Cheng J, Fu Y, Xiao X, Yin H, Lin Y, Chen T, Li B, Yu X, Cai Q, Chen W, Kotta-Loizou I, Xie J. Plants interfere with non-self recognition of a phytopathogenic fungus via proline accumulation to facilitate mycovirus transmission. Nat Commun 2024; 15:4748. [PMID: 38834585 DOI: 10.1038/s41467-024-49110-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Accepted: 05/17/2024] [Indexed: 06/06/2024] Open
Abstract
Non-self recognition is a fundamental aspect of life, serving as a crucial mechanism for mitigating proliferation of molecular parasites within fungal populations. However, studies investigating the potential interference of plants with fungal non-self recognition mechanisms are limited. Here, we demonstrate a pronounced increase in the efficiency of horizontal mycovirus transmission between vegetatively incompatible Sclerotinia sclerotiorum strains in planta as compared to in vitro. This increased efficiency is associated with elevated proline concentration in plants following S. sclerotiorum infection. This surge in proline levels attenuates the non-self recognition reaction among fungi by inhibition of cell death, thereby facilitating mycovirus transmission. Furthermore, our field experiments reveal that the combined deployment of hypovirulent S. sclerotiorum strains harboring hypovirulence-associated mycoviruses (HAVs) together with exogenous proline confers substantial protection to oilseed rape plants against virulent S. sclerotiorum. This unprecedented discovery illuminates a novel pathway by which plants can counteract S. sclerotiorum infection, leveraging the weakening of fungal non-self recognition and promotion of HAVs spread. These promising insights provide an avenue to explore for developing innovative biological control strategies aimed at mitigating fungal diseases in plants by enhancing the efficacy of horizontal HAV transmission.
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Affiliation(s)
- Du Hai
- National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei, China
- The Provincial Key Lab of Plant Pathology of Hubei Province, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, China
- Hubei Hongshan Laboratory, Wuhan, Hubei, China
| | - Jincang Li
- National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei, China
- The Provincial Key Lab of Plant Pathology of Hubei Province, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, China
- Hubei Hongshan Laboratory, Wuhan, Hubei, China
| | - Daohong Jiang
- National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei, China
- The Provincial Key Lab of Plant Pathology of Hubei Province, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, China
- Hubei Hongshan Laboratory, Wuhan, Hubei, China
| | - Jiasen Cheng
- National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei, China
- The Provincial Key Lab of Plant Pathology of Hubei Province, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Yanping Fu
- National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei, China
- The Provincial Key Lab of Plant Pathology of Hubei Province, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Xueqiong Xiao
- National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei, China
- The Provincial Key Lab of Plant Pathology of Hubei Province, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Huanran Yin
- National Key Laboratory of Crop Genetic Improvement and National Center of Plant Gene Research (Wuhan), Huazhong Agricultural University, Wuhan, China
| | - Yang Lin
- National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei, China
- The Provincial Key Lab of Plant Pathology of Hubei Province, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Tao Chen
- National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei, China
- The Provincial Key Lab of Plant Pathology of Hubei Province, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, China
- Hubei Hongshan Laboratory, Wuhan, Hubei, China
| | - Bo Li
- National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei, China
- The Provincial Key Lab of Plant Pathology of Hubei Province, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, China
- Hubei Hongshan Laboratory, Wuhan, Hubei, China
| | - Xiao Yu
- National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei, China
- The Provincial Key Lab of Plant Pathology of Hubei Province, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, China
- Hubei Hongshan Laboratory, Wuhan, Hubei, China
| | - Qing Cai
- National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Wei Chen
- National Key Laboratory of Crop Genetic Improvement and National Center of Plant Gene Research (Wuhan), Huazhong Agricultural University, Wuhan, China
| | - Ioly Kotta-Loizou
- School of Life and Medical Sciences, University of Hertfordshire, Hatfield, UK
- Department of Life Sciences, Imperial College London, London, UK
| | - Jiatao Xie
- National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei, China.
- The Provincial Key Lab of Plant Pathology of Hubei Province, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, China.
- Hubei Hongshan Laboratory, Wuhan, Hubei, China.
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2
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Auxier B, Zhang J, Marquez FR, Senden K, van den Heuvel J, Aanen DK, Snelders E, Debets AJM. The Narrow Footprint of Ancient Balancing Selection Revealed by Heterokaryon Incompatibility Genes in Aspergillus fumigatus. Mol Biol Evol 2024; 41:msae079. [PMID: 38652808 PMCID: PMC11138114 DOI: 10.1093/molbev/msae079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 04/03/2024] [Accepted: 04/11/2024] [Indexed: 04/25/2024] Open
Abstract
In fungi, fusion between individuals leads to localized cell death, a phenomenon termed heterokaryon incompatibility. Generally, the genes responsible for this incompatibility are observed to be under balancing selection resulting from negative frequency-dependent selection. Here, we assess this phenomenon in Aspergillus fumigatus, a human pathogenic fungus with a very low level of linkage disequilibrium as well as an extremely high crossover rate. Using complementation of auxotrophic mutations as an assay for hyphal compatibility, we screened sexual progeny for compatibility to identify genes involved in this process, called het genes. In total, 5/148 (3.4%) offspring were compatible with a parent and 166/2,142 (7.7%) sibling pairs were compatible, consistent with several segregating incompatibility loci. Genetic mapping identified five loci, four of which could be fine mapped to individual genes, of which we tested three through heterologous expression, confirming their causal relationship. Consistent with long-term balancing selection, trans-species polymorphisms were apparent across several sister species, as well as equal allele frequencies within A. fumigatus. Surprisingly, a sliding window genome-wide population-level analysis of an independent dataset did not show increased Tajima's D near these loci, in contrast to what is often found surrounding loci under balancing selection. Using available de novo assemblies, we show that these balanced polymorphisms are restricted to several hundred base pairs flanking the coding sequence. In addition to identifying the first het genes in an Aspergillus species, this work highlights the interaction of long-term balancing selection with rapid linkage disequilibrium decay.
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Affiliation(s)
- Ben Auxier
- Laboratory of Genetics, Wageningen University & Research, Wageningen, the Netherlands
| | - Jianhua Zhang
- Laboratory of Genetics, Wageningen University & Research, Wageningen, the Netherlands
| | | | - Kira Senden
- Laboratory of Genetics, Wageningen University & Research, Wageningen, the Netherlands
| | - Joost van den Heuvel
- Laboratory of Genetics, Wageningen University & Research, Wageningen, the Netherlands
| | - Duur K Aanen
- Laboratory of Genetics, Wageningen University & Research, Wageningen, the Netherlands
| | - Eveline Snelders
- Laboratory of Genetics, Wageningen University & Research, Wageningen, the Netherlands
| | - Alfons J M Debets
- Laboratory of Genetics, Wageningen University & Research, Wageningen, the Netherlands
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3
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Clavé C, Dheur S, Ament-Velásquez SL, Granger-Farbos A, Saupe SJ. het-B allorecognition in Podospora anserina is determined by pseudo-allelic interaction of genes encoding a HET and lectin fold domain protein and a PII-like protein. PLoS Genet 2024; 20:e1011114. [PMID: 38346076 PMCID: PMC10890737 DOI: 10.1371/journal.pgen.1011114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 02/23/2024] [Accepted: 01/29/2024] [Indexed: 02/25/2024] Open
Abstract
Filamentous fungi display allorecognition genes that trigger regulated cell death (RCD) when strains of unlike genotype fuse. Podospora anserina is one of several model species for the study of this allorecognition process termed heterokaryon or vegetative incompatibility. Incompatibility restricts transmission of mycoviruses between isolates. In P. anserina, genetic analyses have identified nine incompatibility loci, termed het loci. Here we set out to clone the genes controlling het-B incompatibility. het-B displays two incompatible alleles, het-B1 and het-B2. We find that the het-B locus encompasses two adjacent genes, Bh and Bp that exist as highly divergent allelic variants (Bh1/Bh2 and Bp1/Bp2) in the incompatible haplotypes. Bh encodes a protein with an N-terminal HET domain, a cell death inducing domain bearing homology to Toll/interleukin-1 receptor (TIR) domains and a C-terminal domain with a predicted lectin fold. The Bp product is homologous to PII-like proteins, a family of small trimeric proteins acting as sensors of adenine nucleotides in bacteria. We show that although the het-B system appears genetically allelic, incompatibility is in fact determined by the non-allelic Bh1/Bp2 interaction while the reciprocal Bh2/Bp1 interaction plays no role in incompatibility. The highly divergent C-terminal lectin fold domain of BH determines recognition specificity. Population studies and genome analyses indicate that het-B is under balancing selection with trans-species polymorphism, highlighting the evolutionary significance of the two incompatible haplotypes. In addition to emphasizing anew the central role of TIR-like HET domains in fungal RCD, this study identifies novel players in fungal allorecognition and completes the characterization of the entire het gene set in that species.
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Affiliation(s)
- Corinne Clavé
- IBGC, UMR 5095, CNRS-Université de Bordeaux, Bordeaux, France
| | - Sonia Dheur
- IBGC, UMR 5095, CNRS-Université de Bordeaux, Bordeaux, France
| | | | | | - Sven J. Saupe
- IBGC, UMR 5095, CNRS-Université de Bordeaux, Bordeaux, France
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4
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Zheng Q, Daskalov A. Microbial gasdermins: More than a billion years of pyroptotic-like cell death. Semin Immunol 2023; 69:101813. [PMID: 37480832 DOI: 10.1016/j.smim.2023.101813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2023] [Revised: 07/16/2023] [Accepted: 07/17/2023] [Indexed: 07/24/2023]
Abstract
In the recent past, the concept of immunity has been extended to eukaryotic and prokaryotic microorganisms, like fungi and bacteria. The latest findings have drawn remarkable evolutionary parallels between metazoan and microbial defense-related genes, unveiling a growing number of shared transkingdom components of immune systems. One such component is the gasdermin family of pore-forming proteins - executioners of a highly inflammatory immune cell death program in mammals, termed pyroptosis. Pyroptotic cell death limits the spread of intracellular pathogens by eliminating infected cells and coordinates the broader inflammatory response to infection. The microbial gasdermins have similarly been implicated in defense-related cell death reactions in fungi, bacteria and archaea. Moreover, the discovery of the molecular regulators of gasdermin cytotoxicity in fungi and bacteria, has established additional evolutionary links to mammalian pyroptotic pathways. Here, we focus on the gasdermin proteins in microorganisms and their role in organismal defense and provide perspective on this remarkable case study in comparative immunology.
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Affiliation(s)
- Qi Zheng
- State Key Laboratory for Managing Biotic and Chemical Treats to the Quality and Safety of Agro-products, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
| | - Asen Daskalov
- State Key Laboratory for Managing Biotic and Chemical Treats to the Quality and Safety of Agro-products, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou, China; ImmunoConcEpT, CNRS UMR 5164, University of Bordeaux, Bordeaux, France.
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5
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Abstract
Investigation of fungal biology has been frequently motivated by the fact that many fungal species are important plant and animal pathogens. Such efforts have contributed significantly toward our understanding of fungal pathogenic lifestyles (virulence factors and strategies) and the interplay with host immune systems. In parallel, work on fungal allorecognition systems leading to the characterization of fungal regulated cell death determinants and pathways, has been instrumental for the emergent concept of fungal immunity. The uncovered evolutionary trans-kingdom parallels between fungal regulated cell death pathways and innate immune systems incite us to reflect further on the concept of a fungal immune system. Here, I briefly review key findings that have shaped the fungal immunity paradigm, providing a perspective on what I consider its most glaring knowledge gaps. Undertaking to fill such gaps would establish firmly the fungal immune system inside the broader field of comparative immunology.
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Affiliation(s)
- Asen Daskalov
- State Key Laboratory for Managing Biotic and Chemical Treats to the Quality and Safety of Agro-products, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
- ImmunoConcEpT, CNRS UMR 5164, University of Bordeaux, Bordeaux, France
- Corresponding author
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6
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Vogan AA, Martinossi-Allibert I, Ament-Velásquez SL, Svedberg J, Johannesson H. The spore killers, fungal meiotic driver elements. Mycologia 2022; 114:1-23. [PMID: 35138994 DOI: 10.1080/00275514.2021.1994815] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
During meiosis, both alleles of any given gene should have equal chances of being inherited by the progeny. There are a number of reasons why, however, this is not the case, with one of the most intriguing instances presenting itself as the phenomenon of meiotic drive. Genes that are capable of driving can manipulate the ratio of alleles among viable meiotic products so that they are inherited in more than half of them. In many cases, this effect is achieved by direct antagonistic interactions, where the driving allele inhibits or otherwise eliminates the alternative allele. In ascomycete fungi, meiotic products are packaged directly into ascospores; thus, the effect of meiotic drive has been given the nefarious moniker, "spore killing." In recent years, many of the known spore killers have been elevated from mysterious phenotypes to well-described systems at genetic, genomic, and molecular levels. In this review, we describe the known diversity of spore killers and synthesize the varied pieces of data from each system into broader trends regarding genome architecture, mechanisms of resistance, the role of transposable elements, their effect on population dynamics, speciation and gene flow, and finally how they may be developed as synthetic drivers. We propose that spore killing is common, but that it is under-observed because of a lack of studies on natural populations. We encourage researchers to seek new spore killers to build on the knowledge that these remarkable genetic elements can teach us about meiotic drive, genomic conflict, and evolution more broadly.
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Affiliation(s)
- Aaron A Vogan
- Systematic Biology, Department of Organismal Biology, Uppsala University, 752 36, Uppsala, Sweden
| | - Ivain Martinossi-Allibert
- Systematic Biology, Department of Organismal Biology, Uppsala University, 752 36, Uppsala, Sweden.,Institut de Biochimie et de Génétique Cellulaire, UMR 5095 CNRS, Université de Bordeaux, 33077, Bordeaux CEDEX, France
| | - S Lorena Ament-Velásquez
- Systematic Biology, Department of Organismal Biology, Uppsala University, 752 36, Uppsala, Sweden
| | - Jesper Svedberg
- Department of Biomolecular Engineering, University of California, -Santa Cruz, Santa Cruz, California 95064
| | - Hanna Johannesson
- Systematic Biology, Department of Organismal Biology, Uppsala University, 752 36, Uppsala, Sweden
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7
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Stauber L, Croll D, Prospero S. Temporal changes in pathogen diversity in a perennial plant-pathogen-hyperparasite system. Mol Ecol 2022; 31:2073-2088. [PMID: 35122694 PMCID: PMC9540319 DOI: 10.1111/mec.16386] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 01/26/2022] [Accepted: 01/31/2022] [Indexed: 11/27/2022]
Abstract
Hyperparasites can affect the evolution of pathosystems by influencing the stability of both pathogen and host populations. However, how pathogens of perennial hosts evolve in the presence of a hyperparasite has rarely been studied. Here, we investigated temporal changes in genetic diversity of the invasive chestnut blight pathogen Cryphonectria parasitica in the presence of its parasitic mycovirus Cryphonectria hypovirus 1 (CHV1). The virus reduces fungal virulence and represents an effective natural biocontrol agent against chestnut blight in Europe. We analysed genome‐wide diversity and CHV1 prevalence in C. parasitica populations in southern Switzerland that were sampled twice at an interval of about 30 years. Overall, we found that both pathogen population structure and CHV1 prevalence were retained over time. The results suggest that recent bottlenecks have influenced the structure of C. parasitica populations in southern Switzerland. Strong balancing selection signals were found at a single vegetative incompatibility (vic) locus, consistent with negative frequency‐dependent selection imposed by the vegetative incompatibility system. High levels of mating among related individuals (i.e., inbreeding) and genetic drift are probably at the origin of imbalanced allele ratios at vic loci and subsequently low vc type diversity. Virus infection rates were stable at ~30% over the study period and we found no significant impact of the virus on fungal population diversity. Consequently, the efficacy of CHV1‐mediated biocontrol was probably retained.
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Affiliation(s)
- Lea Stauber
- Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Birmensdorf, Switzerland.,Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, Switzerland.,Department of Environmental Sciences, University of Basel, Switzerland
| | - Daniel Croll
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, Switzerland
| | - Simone Prospero
- Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Birmensdorf, Switzerland
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8
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Daskalov A, Glass NL. Gasdermin and Gasdermin-Like Pore-Forming Proteins in Invertebrates, Fungi and Bacteria. J Mol Biol 2021; 434:167273. [PMID: 34599942 DOI: 10.1016/j.jmb.2021.167273] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 09/22/2021] [Accepted: 09/22/2021] [Indexed: 10/20/2022]
Abstract
The gasdermin family of pore-forming proteins (PFPs) has recently emerged as key molecular players controlling immune-related cell death in mammals. Characterized mammalian gasdermins are activated through proteolytic cleavage by caspases or serine proteases, which remove an inhibitory carboxy-terminal domain, allowing the pore-formation process. Processed gasdermins form transmembrane pores permeabilizing the plasma membrane, which often results in lytic and inflammatory cell death. While the gasdermin-dependent cell death (pyroptosis) has been predominantly characterized in mammals, it now has become clear that gasdermins also control cell death in early vertebrates (teleost fish) and invertebrate animals such as corals (Cnidaria). Moreover, gasdermins and gasdermin-like proteins have been identified and characterized in taxa outside of animals, notably Fungi and Bacteria. Fungal and bacterial gasdermins share many features with mammalian gasdermins including their mode of activation through proteolysis. It has been shown that in some cases the proteolytic activation is executed by evolutionarily related proteases acting downstream of proteins resembling immune receptors controlling pyroptosis in mammals. Overall, these findings establish gasdermins and gasdermin-regulated cell death as an extremely ancient mechanism of cellular suicide and build towards an understanding of the evolution of regulated cell death in the context of immunology. Here, we review the broader gasdermin family, focusing on recent discoveries in invertebrates, fungi and bacteria.
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Affiliation(s)
- Asen Daskalov
- Institut de Biochimie et Génétique Cellulaires, University of Bordeaux, France.
| | - N Louise Glass
- The Plant and Microbial Biology Department, The University of California, Berkeley, CA 94720-3102, United States
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9
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Spontaneous changes in somatic compatibility in Fusarium circinatum. Fungal Biol 2021; 125:725-732. [PMID: 34420699 DOI: 10.1016/j.funbio.2021.04.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Revised: 04/08/2021] [Accepted: 04/26/2021] [Indexed: 11/24/2022]
Abstract
Filamentous fungi grow by the elaboration of hyphae, which may fuse to form a network as a colony develops. Fusion of hyphae can occur between genetically different individuals, provided they share a common allele at loci affecting somatic compatibility. Diversity in somatic compatibility phenotypes reduces the frequency of hyphal fusion in a population, thereby slowing the spread of deleterious genetic elements such as viruses and plasmids, which require direct cytoplasmic contact for transmission. Diverse somatic compatibility phenotypes can be generated by recombining alleles through sexual reproduction, but this mechanism may not fully account for the diversity found in nature. For example, multiple compatibility phenotypes of Fusarium circinatum were shown to be associated with the same clonal lineage, which implies they were derived by a mutation rather than recombination through sexual reproduction. Experimental tests of this hypothesis confirmed that spontaneous changes in somatic compatibility can occur at a frequency between 5 and 8 per million spores. Genomic analysis of F. circinatum strains with altered somatic compatibility revealed no consistent evidence of recombination and supported the hypothesis that a spontaneous mutation generated the observed phenotypic change. Genes known to be involved in somatic compatibility had no mutations, suggesting that mutation occurred in a gene with an as yet unexplored function in somatic compatibility.
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10
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Auxier B, Scholtmeijer K, van Peer AF, Baars JJP, Debets AJM, Aanen DK. Cytoplasmic Mixing, Not Nuclear Coexistence, Can Explain Somatic Incompatibility in Basidiomycetes. Microorganisms 2021; 9:1248. [PMID: 34201361 PMCID: PMC8229728 DOI: 10.3390/microorganisms9061248] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 06/03/2021] [Accepted: 06/04/2021] [Indexed: 12/03/2022] Open
Abstract
Nonself recognition leading to somatic incompatibility (SI) is commonly used by mycologists to distinguish fungal individuals. Despite this, the process remains poorly understood in basidiomycetes as all current models of SI are based on genetic and molecular research in ascomycete fungi. Ascomycete fungi are mainly found in a monokaryotic stage, with a single type of haploid nuclei, and only briefly during mating do two genomes coexist in heterokaryotic cells. The sister phylum, Basidiomycota, differs in several relevant aspects. Basidiomycete fungi have an extended heterokaryotic stage, and SI is generally observed between heterokaryons instead of between homokaryons. Additionally, considerable nuclear migration occurs during a basidiomycete mating reaction, introducing a nucleus into a resident homokaryon with cytoplasmic mixing limited to the fused or neighboring cells. To accommodate these differences, we describe a basidiomycete model for nonself recognition using post-translational modification, based on a reader-writer system as found in other organisms. This post-translational modification combined with nuclear migration allows for the coexistence of two genomes in one individual while maintaining nonself recognition during all life stages. Somewhat surprisingly, this model predicts localized cell death during mating, which is consistent with previous observations but differs from the general assumptions of basidiomycete mating. This model will help guide future research into the mechanisms behind basidiomycete nonself recognition.
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Affiliation(s)
- Ben Auxier
- Laboratory of Genetics, Wageningen University and Research, 6708 PB Wageningen, The Netherlands;
| | - Karin Scholtmeijer
- Mushroom Group, Plant Breeding Department, Wageningen University and Research, 6708 PB Wageningen, The Netherlands; (K.S.); (A.F.v.P.); (J.J.P.B.)
| | - Arend F. van Peer
- Mushroom Group, Plant Breeding Department, Wageningen University and Research, 6708 PB Wageningen, The Netherlands; (K.S.); (A.F.v.P.); (J.J.P.B.)
| | - Johan J. P. Baars
- Mushroom Group, Plant Breeding Department, Wageningen University and Research, 6708 PB Wageningen, The Netherlands; (K.S.); (A.F.v.P.); (J.J.P.B.)
- CNC Grondstoffen, P.O. Box 13, 6590 AA Gennep, The Netherlands
| | - Alfons J. M. Debets
- Laboratory of Genetics, Wageningen University and Research, 6708 PB Wageningen, The Netherlands;
| | - Duur K. Aanen
- Laboratory of Genetics, Wageningen University and Research, 6708 PB Wageningen, The Netherlands;
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11
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Gonçalves AP, Heller J, Rico-Ramírez AM, Daskalov A, Rosenfield G, Glass NL. Conflict, Competition, and Cooperation Regulate Social Interactions in Filamentous Fungi. Annu Rev Microbiol 2020; 74:693-712. [PMID: 32689913 DOI: 10.1146/annurev-micro-012420-080905] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Social cooperation impacts the development and survival of species. In higher taxa, kin recognition occurs via visual, chemical, or tactile cues that dictate cooperative versus competitive interactions. In microbes, the outcome of cooperative versus competitive interactions is conferred by identity at allorecognition loci, so-called kind recognition. In syncytial filamentous fungi, the acquisition of multicellularity is associated with somatic cell fusion within and between colonies. However, such intraspecific cooperation entails risks, as fusion can transmit deleterious genotypes or infectious components that reduce fitness, or give rise to cheaters that can exploit communal goods without contributing to their production. Allorecognition mechanisms in syncytial fungi regulate somatic cell fusion by operating precontact during chemotropic interactions, during cell adherence, and postfusion by triggering programmed cell death reactions. Alleles at fungal allorecognition loci are highly polymorphic, fall into distinct haplogroups, and show evolutionary signatures of balancing selection, similar to allorecognition loci across the tree of life.
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Affiliation(s)
- A Pedro Gonçalves
- Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, USA.,Current Affiliation: Institute of Molecular Biology, Academia Sinica, Nangang District, Taipei 115, Taiwan
| | - Jens Heller
- Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, USA.,Current Affiliation: Perfect Day, Inc., Emeryville, California 94608, USA
| | - Adriana M Rico-Ramírez
- Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, USA
| | - Asen Daskalov
- Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, USA.,Current Affiliation: Institut Européen de Chimie et Biologie, 33600 Pessac, France
| | - Gabriel Rosenfield
- Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, USA.,Current Affiliation: Department of Genetics, Stanford University School of Medicine, Stanford, California 94305, USA
| | - N Louise Glass
- Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, USA.,Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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12
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Daskalov A, Gladieux P, Heller J, Glass NL. Programmed Cell Death in Neurospora crassa Is Controlled by the Allorecognition Determinant rcd-1. Genetics 2019; 213:1387-1400. [PMID: 31636083 PMCID: PMC6893366 DOI: 10.1534/genetics.119.302617] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2019] [Accepted: 10/17/2019] [Indexed: 12/31/2022] Open
Abstract
Nonself recognition following cell fusion between genetically distinct individuals of the same species in filamentous fungi often results in a programmed cell death (PCD) reaction, where the heterokaryotic fusion cell is compartmentalized and rapidly killed. The allorecognition process plays a key role as a defense mechanism that restricts genome exploitation, resource plundering, and the spread of deleterious senescence plasmids and mycoviruses. Although a number of incompatibility systems have been described that function in mature hyphae, less is known about the PCD pathways in asexual spores, which represent the main infectious unit in various human and plant fungal pathogens. Here, we report the identification of regulator of cell death-1 (rcd-1), a novel allorecognition gene, controlling PCD in germinating asexual spores of Neurospora crassa; rcd-1 is one of the most polymorphic genes in the genomes of wild N. crassa isolates. The coexpression of two antagonistic rcd-1-1 and rcd-1-2 alleles was necessary and sufficient to trigger cell death in fused germlings and in hyphae. Based on analysis of wild populations of N. crassa and N. discreta, rcd-1 alleles appeared to be under balancing selection and associated with trans-species polymorphisms. We shed light on genomic rearrangements that could have led to the emergence of the incompatibility system in Neurospora and show that rcd-1 belongs to a much larger gene family in fungi. Overall, our work contributes toward a better understanding of allorecognition and PCD in an underexplored developmental stage of filamentous fungi.
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Affiliation(s)
- Asen Daskalov
- Plant and Microbial Biology Department, The University of California, Berkeley, California 94720
| | - Pierre Gladieux
- UMR BGPI, INRA, CIRAD, Montpellier SupAgro, University Montpellier, 34060, France
| | - Jens Heller
- Plant and Microbial Biology Department, The University of California, Berkeley, California 94720
- Environmental Genomics and Systems Biology Division, The Lawrence Berkeley National Laboratory, California 94720
| | - N Louise Glass
- Plant and Microbial Biology Department, The University of California, Berkeley, California 94720
- Environmental Genomics and Systems Biology Division, The Lawrence Berkeley National Laboratory, California 94720
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