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Bringhurst B, Greenwold M, Kellner K, Seal JN. Symbiosis, dysbiosis and the impact of horizontal exchange on bacterial microbiomes in higher fungus-gardening ants. Sci Rep 2024; 14:3231. [PMID: 38332146 PMCID: PMC10853281 DOI: 10.1038/s41598-024-53218-6] [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: 09/28/2023] [Accepted: 01/30/2024] [Indexed: 02/10/2024] Open
Abstract
Advances in our understanding of symbiotic stability have demonstrated that microorganisms are key to understanding the homeostasis of obligate symbioses. Fungus-gardening ants are excellent model systems for exploring how microorganisms may be involved in symbiotic homeostasis as the host and symbionts are macroscopic and can be easily experimentally manipulated. Their coevolutionary history has been well-studied; examinations of which have depicted broad clade-to-clade specificity between the ants and fungus. Few studies hitherto have addressed the roles of microbiomes in stabilizing these associations. Here, we quantified changes in microbiome structure as a result of experimentally induced horizontal exchange of symbionts. This was done by performing cross-fostering experiments forcing ants to grow novel fungi and comparing known temporally unstable (undergoing dysbiosis) and stable combinations. We found that fungus-gardening ants alter their unstable, novel garden microbiomes into configurations like those found in native gardens. Patterns of dysbiosis/symbiosis appear to be predictable in that two related species with similar specificity patterns also show similar patterns of microbial change, whereas a species with more relaxed specificity does not show such microbiome change or restructuring when growing different fungi. It appears that clade-to-clade specificity patterns are the outcomes of community-level interactions that promote stability or cause symbiotic collapse.
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Affiliation(s)
- Blake Bringhurst
- Department of Biology, University of Texas at Tyler, 3900 University Blvd, Tyler, TX, 757998, USA
- Department of Evolution, Ecology and Organismal Biology, The Ohio State University, 1315 Kinnear Rd, Columbus, OH, 43212, USA
| | - Matthew Greenwold
- Department of Biology, University of Texas at Tyler, 3900 University Blvd, Tyler, TX, 757998, USA
| | - Katrin Kellner
- Department of Biology, University of Texas at Tyler, 3900 University Blvd, Tyler, TX, 757998, USA
| | - Jon N Seal
- Department of Biology, University of Texas at Tyler, 3900 University Blvd, Tyler, TX, 757998, USA.
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Shang J, Hong S, Wang C. Fights on the surface prior to fungal invasion of insects. PLoS Pathog 2024; 20:e1011994. [PMID: 38386619 PMCID: PMC10883574 DOI: 10.1371/journal.ppat.1011994] [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] [Indexed: 02/24/2024] Open
Abstract
Entomopathogenic fungi (EPF) infect insects by landing on and penetrating cuticles. Emerging evidence has shown that, prior to the invasion of insects, fungal cells have to battle and overcome diverse challenges, including the host behavioral defenses, colonization resistance mediated by ectomicrobiotas, host recognition, and generation of enough penetration pressure. The ascomycete EPF such as Metarhizium and Beauveria can thus produce adhesive proteins and/or the exopolysaccharide mucilage to tightly glue fungal cells on cuticles. Producing antimicrobial peptides and chemical compounds can enable EPF to outcompete cuticular defensive microbes. The use of divergent membrane receptors, accumulation, and quick degradation of lipid droplets in conidial cells can help EPF recognize proper hosts and build up cellular turgor to breach cuticles for systematic invasion. Further investigations are still required to unveil the multifaceted and intricate relationships between EPF and insect hosts.
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Affiliation(s)
- Junmei Shang
- Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
| | - Song Hong
- Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
| | - Chengshu Wang
- Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
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3
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Hong S, Sun Y, Chen H, Zhao P, Wang C. Fungus-insect interactions beyond bilateral regimes: the importance and strategy to outcompete host ectomicrobiomes by fungal parasites. Curr Opin Microbiol 2023; 74:102336. [PMID: 37320866 DOI: 10.1016/j.mib.2023.102336] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 05/07/2023] [Accepted: 05/17/2023] [Indexed: 06/17/2023]
Abstract
Fungus-insect interactions have long been investigated at the bilateral level to unveil the factors involved in mediating fungal entomopathogenicity and insect antifungal immunity. Emerging evidence has shown that insect cuticles are inhabited by different bacteria that can delay and deter fungal parasite infections. Entomopathogenic fungi (EPF), however, have evolved strategies to combat the colonization resistance mediated by insect ectomicrobiomes by producing antimicrobial peptides or antibiotic compounds. Deprivation of micronutrients may also be employed by EPF to counteract the ectomicrobiome antagonism. Further investigations of insect ectomicrobiome assemblage and fungal factors involved in outcompeting cuticular microbiomes may benefit the development of cost-effective mycoinsecticides while protecting ecologically and economically important insect species.
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Affiliation(s)
- Song Hong
- Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China; CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yanlei Sun
- Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China; CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Haimin Chen
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Pengfei Zhao
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Chengshu Wang
- Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China; CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing 100049, China; School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China.
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Hong S, Sun Y, Chen H, Wang C. Suppression of the insect cuticular microbiomes by a fungal defensin to facilitate parasite infection. THE ISME JOURNAL 2023; 17:1-11. [PMID: 36127432 PMCID: PMC9751272 DOI: 10.1038/s41396-022-01323-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 09/07/2022] [Accepted: 09/08/2022] [Indexed: 12/24/2022]
Abstract
Insects can assemble defensive microbiomes on their body surfaces to defend against fungal parasitic infections. The strategies employed by fungal pathogens to combat host cuticular microbiotas remains unclear. Here, we report the identification and functional characterization of the defensin-like antimicrobial gene BbAMP1 encoded by the entomopathogenic fungus Beauveria bassiana. The mature peptide of BbAMP1 can coat fungal spores and can be secreted by the fungus to target and damage Gram-positive bacterial cells. Significant differences in insect survival were observed between the wild-type and BbAMP1 mutant strains during topical infection but not during injection assays that bypassed insect cuticles. Thus, BbAMP1 deletion considerably reduced fungal virulence while gene overexpression accelerated the fungal colonization of insects compared with the wild-type strain in natural infections. Topical infection of axenic Drosophila adults evidenced no difference in fly survivals between strains. However, the gnotobiotic infections with the addition of Gram-positive but not Gram-negative bacterial cells in fungal spore suspensions substantially increased the survival of the flies treated with ∆BbAMP1 compared to those infected by the wild-type and gene-overexpression strains. Bacterial colony counts and microbiome analysis confirmed that BbAMP1 could assist the fungus to manipulate insect surface bacterial loads. This study reveals that fungal defensin can suppress the host surface defensive microbiomes, which underscores the importance to extend the research scope of fungus-host interactions.
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Affiliation(s)
- Song Hong
- Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, 200032, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yanlei Sun
- Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, 200032, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Haimin Chen
- Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, 200032, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Chengshu Wang
- Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, 200032, China.
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, 100049, China.
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China.
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Bringhurst B, Allert M, Greenwold M, Kellner K, Seal JN. Environments and Hosts Structure the Bacterial Microbiomes of Fungus-Gardening Ants and their Symbiotic Fungus Gardens. MICROBIAL ECOLOGY 2022:10.1007/s00248-022-02138-x. [PMID: 36344828 DOI: 10.1007/s00248-022-02138-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 10/24/2022] [Indexed: 06/16/2023]
Abstract
The fungus gardening-ant system is considered a complex, multi-tiered symbiosis, as it is composed of ants, their fungus, and microorganisms associated with either ants or fungus. We examine the bacterial microbiome of Trachymyrmex septentrionalis and Mycetomoellerius turrifex ants and their symbiotic fungus gardens, using 16S rRNA Illumina sequencing, over a region spanning approximately 350 km (east and central Texas). Typically, microorganisms can be acquired from a parent colony (vertical transmission) or from the environment (horizontal transmission). Because the symbiosis is characterized by co-dispersal of the ants and fungus, elements of both ant and fungus garden microbiome could be characterized by vertical transmission. The goals of this study were to explore how both the ant and fungus garden bacterial microbiome are acquired. The main findings were that different mechanisms appear to explain the structure the microbiomes of ants and their symbiotic fungus gardens. Ant associated microbiomes had a strong host ant signature, which could be indicative of vertical inheritance of the ant associated bacterial microbiome or an unknown mechanism of active uptake or screening. On the other hand, the bacterial microbiome of the fungus garden was more complex in that some bacterial taxa appear to be structured by the ant host species, whereas others by fungal lineage or the environment (geographic region). Thus bacteria in fungus gardens appear to be acquired both horizontally and vertically.
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Affiliation(s)
- Blake Bringhurst
- Department of Biology, University of Texas at Tyler, 3900 University Blvd, Tyler, TX, 75799, USA
| | - Mattea Allert
- Department of Biology, University of Texas at Tyler, 3900 University Blvd, Tyler, TX, 75799, USA
| | - Matthew Greenwold
- Department of Biology, University of Texas at Tyler, 3900 University Blvd, Tyler, TX, 75799, USA
| | - Katrin Kellner
- Department of Biology, University of Texas at Tyler, 3900 University Blvd, Tyler, TX, 75799, USA
| | - Jon N Seal
- Department of Biology, University of Texas at Tyler, 3900 University Blvd, Tyler, TX, 75799, USA.
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Sun Y, Hong S, Chen H, Yin Y, Wang C. Production of Helvolic Acid in Metarhizium Contributes to Fungal Infection of Insects by Bacteriostatic Inhibition of the Host Cuticular Microbiomes. Microbiol Spectr 2022; 10:e0262022. [PMID: 36047778 PMCID: PMC9602595 DOI: 10.1128/spectrum.02620-22] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2022] [Accepted: 08/15/2022] [Indexed: 01/04/2023] Open
Abstract
The nortriterpenoid helvolic acid (HA) has potent antibiotic activities and can be produced by different fungi, yet HA function remains elusive. Here, we report the chemical biology of HA production in the insect pathogen Metarhizium robertsii. After deletion of the core oxidosqualene cyclase gene in Metarhizium, insect survival rates were significantly increased compared to those of insects treated with the wild type and the gene-rescued strain during topical infections but not during injection assays to bypass insect cuticles. Further gnotobiotic infection of axenic Drosophila adults confirmed the HA contribution to fungal infection by inhibiting bacterial competitors in an inoculum-dependent manner. Loss of HA production substantially impaired fungal spore germination and membrane penetration abilities relative to the WT and gene-complemented strains during challenge with different Gram-positive bacteria. Quantitative microbiome analysis revealed that HA production could assist the fungus to suppress the Drosophila cuticular microbiomes by exerting a bacteriostatic rather than bactericidal effect. Our data unveil the chemical ecology of HA and highlight the fact that fungal pathogens have to cope with the host cuticular microbiomes prior to successful infection of hosts. IMPORTANCE Emerging evidence has shown that the plant and animal surface microbiomes can defend hosts against fungal parasite infections. The strategies employed by fungal pathogens to combat the antagonistic inhibition of insect surface bacteria are still elusive. In this study, we found that the potent antibiotic helvolic acid (HA) produced by the insect pathogen Metarhizium robertsii contributes to natural fungal infection of insect hosts. Antibiotic and gnotobiotic infection assays confirmed that HA could facilitate fungal infection of insects by suppression of the host cuticular microbiomes through its bacteriostatic instead of bactericidal activities. The data from this study provide insights into the novel chemical biology of fungal secondary metabolisms.
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Affiliation(s)
- Yanlei Sun
- Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
| | - Song Hong
- Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
| | - Haimin Chen
- Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Ying Yin
- Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
| | - Chengshu Wang
- Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
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7
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The bacterial and fungal communities of the larval midgut of Spodoptera frugiperda (Lepidoptera: Noctuidae) varied by feeding on two cruciferous vegetables. Sci Rep 2022; 12:13063. [PMID: 35906471 PMCID: PMC9338029 DOI: 10.1038/s41598-022-17278-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2022] [Accepted: 07/22/2022] [Indexed: 11/08/2022] Open
Abstract
Spodoptera frugiperda is a highly polyphagous pest worldwide with a wide host range that causes serious losses to many economically important crops. Recently, insect-microbe associations have become a hot spot in current entomology research, and the midgut microbiome of S. frugiperda has been investigated, while the effects of cruciferous vegetables remain unknown. In this study, the growth of S. frugiperda larvae fed on an artificial diet, Brassica campestris and Brassica oleracea for 7 days was analyzed. Besides, the microbial community and functional prediction analyses of the larval midguts of S. frugiperda fed with different diets were performed by high-throughput sequencing. Our results showed that B. oleracea inhibited the growth of S. frugiperda larvae. The larval midgut microbial community composition and structure were significantly affected by different diets. Linear discriminant analysis effect size (LEfSe) suggested 20 bacterial genera and 2 fungal genera contributed to different gut microbial community structures. The functional classification of the midgut microbiome analyzed by PICRUSt and FUNGuild showed that the most COG function categories of midgut bacterial function were changed by B. oleracea, while the guilds of fungal function were altered by B. campestris significantly. These results showed that the diversity and structure of the S. frugiperda midgut microbial community were affected by cruciferous vegetable feeding. Our study provided a preliminary understanding of the role of midgut microbes in S. frugiperda larvae in response to cruciferous vegetables.
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