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Shi PQ, Wang L, Chen XY, Wang K, Wu QJ, Turlings TCJ, Zhang PJ, Qiu BL. Rickettsia transmission from whitefly to plants benefits herbivore insects but is detrimental to fungal and viral pathogens. mBio 2024; 15:e0244823. [PMID: 38315036 PMCID: PMC10936170 DOI: 10.1128/mbio.02448-23] [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: 09/08/2023] [Accepted: 01/02/2024] [Indexed: 02/07/2024] Open
Abstract
Bacterial endosymbionts play important roles in the life histories of herbivorous insects by impacting their development, survival, reproduction, and stress tolerance. How endosymbionts may affect the interactions between plants and insect herbivores is still largely unclear. Here, we show that endosymbiotic Rickettsia belli can provide mutual benefits also outside of their hosts when the sap-sucking whitefly Bemisia tabaci transmits them to plants. This transmission facilitates the spread of Rickettsia but is shown to also enhance the performance of the whitefly and co-infesting caterpillars. In contrast, Rickettsia infection enhanced plant resistance to several pathogens. Inside the plants, Rickettsia triggers the expression of salicylic acid-related genes and the two pathogen-resistance genes TGA 2.1 and VRP, whereas they repressed genes of the jasmonic acid pathway. Performance experiments using wild type and mutant tomato plants confirmed that Rickettsia enhances the plants' suitability for insect herbivores but makes them more resistant to fungal and viral pathogens. Our results imply that endosymbiotic Rickettsia of phloem-feeding insects affects plant defenses in a manner that facilitates their spread and transmission. This novel insight into how insects can exploit endosymbionts to manipulate plant defenses also opens possibilities to interfere with their ability to do so as a crop protection strategy. IMPORTANCE Most insects are associated with symbiotic bacteria in nature. These symbionts play important roles in the life histories of herbivorous insects by impacting their development, survival, reproduction as well as stress tolerance. Rickettsia is one important symbiont to the agricultural pest whitefly Bemisia tabaci. Here, for the first time, we revealed that the persistence of Rickettsia symbionts in tomato leaves significantly changed the defense pattern of tomato plants. These changes benefit both sap-feeding and leaf-chewing herbivore insects, such as increasing the fecundity of whitefly adults, enhancing the growth and development of the noctuid Spodoptera litura, but reducing the pathogenicity of Verticillium fungi and TYLCV virus to tomato plants distinctively. Our study unraveled a new horizon for the multiple interaction theories among plant-insect-bacterial symbionts.
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Affiliation(s)
- Pei-Qiong Shi
- Engineering Research Center of Biotechnology for Active Substances, Ministry of Education, Chongqing Normal University, Chongqing, China
| | - Lei Wang
- Engineering Research Center of Biotechnology for Active Substances, Ministry of Education, Chongqing Normal University, Chongqing, China
| | - Xin-Yi Chen
- Engineering Research Center of Biotechnology for Active Substances, Ministry of Education, Chongqing Normal University, Chongqing, China
| | - Kai Wang
- Department of Computational Medicine and Bioinformatics, School of Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | - Qing-Jun Wu
- Institute of Vegetables & Flowers, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Ted C. J. Turlings
- FARCE Laboratory, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Peng-Jun Zhang
- College of Life and Environmental Sciences, Hangzhou Normal University, Huangzhou, China
| | - Bao-Li Qiu
- Engineering Research Center of Biotechnology for Active Substances, Ministry of Education, Chongqing Normal University, Chongqing, China
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Bing XL, Xia CB, Ye QT, Gong X, Cui JR, Peng CW, Hong XY. Wolbachia manipulates reproduction of spider mites by influencing herbivore salivary proteins. PEST MANAGEMENT SCIENCE 2023; 79:315-323. [PMID: 36151871 DOI: 10.1002/ps.7201] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 09/01/2022] [Accepted: 09/24/2022] [Indexed: 06/16/2023]
Abstract
BACKGROUND The endosymbiont Wolbachia is known for manipulating host reproduction. Wolbachia also can affect host fitness by mediating interactions between plant and herbivores. However, it remains unclear whether saliva proteins are involved in this process. RESULTS We found that Wolbachia infection decreased the number of deposited eggs but increased the egg hatching rate in the spider mite Tetranychus urticae Koch (Acari: Tetranychidae), a cosmopolitan pest that infects >1000 species of plants. Transcriptomic and proteomic analyses revealed that Wolbachia-infected mites upregulated the gene expression levels of many T. urticae salivary proteins including a cluster of Tetranychidae-specific, functionally uncharacterized SHOT1s (secreted host-responsive proteins of Tetranychidae). The SHOT1 genes were expressed more in the feeding stages (nymphs and adults) of mites than in eggs and highly enriched in the proterosomas. RNA interference experiments showed that knockdown of SHOT1s significantly decreased Wolbachia density, increased the number of deposited eggs and decreased the egg hatching rate. CONCLUSION Together, these results indicate that SHOT1s are positively correlated with Wolbachia density and account for Wolbachia-mediated phenotypes. Our results provide new evidence that herbivore salivary proteins are related to Wolbachia-mediated manipulations of host performance on plants. © 2022 Society of Chemical Industry.
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Affiliation(s)
- Xiao-Li Bing
- Department of Entomology, Nanjing Agricultural University, Nanjing, China
| | - Cai-Bei Xia
- Department of Entomology, Nanjing Agricultural University, Nanjing, China
| | - Qing-Tong Ye
- Department of Entomology, Nanjing Agricultural University, Nanjing, China
| | - Xue Gong
- Department of Entomology, Nanjing Agricultural University, Nanjing, China
| | - Jia-Rong Cui
- Department of Entomology, Nanjing Agricultural University, Nanjing, China
| | - Chang-Wu Peng
- Department of Entomology, Nanjing Agricultural University, Nanjing, China
| | - Xiao-Yue Hong
- Department of Entomology, Nanjing Agricultural University, Nanjing, China
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Callejas-Chavero A, Martínez-Hernández DG, Vargas-Mendoza CF, Flores-Martínez A. Herbivory in Myrtillocactus geometrizans (Cactaceae): Do Parasitoids Provide Indirect Defense or a Direct Advantage? PLANTS (BASEL, SWITZERLAND) 2022; 12:47. [PMID: 36616177 PMCID: PMC9824105 DOI: 10.3390/plants12010047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/12/2022] [Revised: 11/27/2022] [Accepted: 12/12/2022] [Indexed: 06/17/2023]
Abstract
Plants respond to herbivory in diverse, complex ways, ranging from avoidance or tolerance to indirect defense mechanisms such as attracting natural enemies of herbivores, i.e., parasitoids or predators, to strengthen their defense. Defense provided by parasitoids to cultivated plants is well documented and is used in biological control programs. However, its effectiveness on wild plants under natural conditions has been little studied. Such is the case of the cactus Myrtilllocactus geometrizans (known in Mexico as garambullo), which is consumed by the soft-scale insect Toumeyella martinezae (herbivore) which, in turn, is host to the parasitoid wasp Mexidalgus toumeyellus, and mutualist with the ant Liometopum apiculatum, that tenders and protects it. This study explores the role of the parasitoid as an indirect defense, by examining its effect on both the herbivore and the plant, and how this interaction is affected by the presence of the mutualistic ant. We found that scales adversely affect the cactus' growth, flower, and fruit production, as well as its progeny's performance, as seedlings from scale-infested garambullo plants were shorter, and it also favors the presence of fungus (sooty mold). The parasitoid responded positively to herbivore abundance, but the presence of ants reduced the intensity of parasitism. Our results show that parasitoids can function as an indirect defense, but their effectiveness is reduced by the presence of the herbivore's mutualistic ant.
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Affiliation(s)
- Alicia Callejas-Chavero
- Laboratorio de Ecología Vegetal, Departamento de Botánica, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Mexico City 11340, Mexico
| | - Diana Guadalupe Martínez-Hernández
- Laboratorio de Ecología Vegetal, Departamento de Botánica, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Mexico City 11340, Mexico
| | - Carlos Fabian Vargas-Mendoza
- Laboratorio de Variación Biológica y Evolución, Departamento de Zoología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Mexico City 11340, Mexico
| | - Arturo Flores-Martínez
- Laboratorio de Ecología Vegetal, Departamento de Botánica, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Mexico City 11340, Mexico
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Jeckel AM, Beran F, Züst T, Younkin G, Petschenka G, Pokharel P, Dreisbach D, Ganal-Vonarburg SC, Robert CAM. Metabolization and sequestration of plant specialized metabolites in insect herbivores: Current and emerging approaches. Front Physiol 2022; 13:1001032. [PMID: 36237530 PMCID: PMC9552321 DOI: 10.3389/fphys.2022.1001032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Accepted: 08/22/2022] [Indexed: 11/13/2022] Open
Abstract
Herbivorous insects encounter diverse plant specialized metabolites (PSMs) in their diet, that have deterrent, anti-nutritional, or toxic properties. Understanding how they cope with PSMs is crucial to understand their biology, population dynamics, and evolution. This review summarizes current and emerging cutting-edge methods that can be used to characterize the metabolic fate of PSMs, from ingestion to excretion or sequestration. It further emphasizes a workflow that enables not only to study PSM metabolism at different scales, but also to tackle and validate the genetic and biochemical mechanisms involved in PSM resistance by herbivores. This review thus aims at facilitating research on PSM-mediated plant-herbivore interactions.
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Affiliation(s)
- Adriana Moriguchi Jeckel
- Laboratory of Chemical Ecology, Institute of Plant Sciences, University of Bern, Bern, Switzerland
| | - Franziska Beran
- Department of Insect Symbiosis, Max Planck Institute for Chemical Ecology, Jena, Germany
| | - Tobias Züst
- Department of Systematic and Evolutionary Botany, University of Zürich, Zürich, Switzerland
| | - Gordon Younkin
- Boyce Thompson Institute, Ithaca, NY, United States
- Plant Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY, United States
| | - Georg Petschenka
- Department of Applied Entomology, Institute of Phytomedicine, University of Hohenheim, Stuttgart, Germany
| | - Prayan Pokharel
- Department of Applied Entomology, Institute of Phytomedicine, University of Hohenheim, Stuttgart, Germany
| | - Domenic Dreisbach
- Institute for Inorganic and Analytical Chemistry, Justus Liebig University Giessen, Giessen, Germany
| | - Stephanie Christine Ganal-Vonarburg
- Department of Visceral Surgery and Medicine, Bern University Hospital, University of Bern, Bern, Switzerland
- Department for BioMedical Research, Visceral Surgery and Medicine, University of Bern, Bern, Switzerland
| | - Christelle Aurélie Maud Robert
- Laboratory of Chemical Ecology, Institute of Plant Sciences, University of Bern, Bern, Switzerland
- *Correspondence: Christelle Aurélie Maud Robert,
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Yamasaki Y, Sumioka H, Takiguchi M, Uemura T, Kihara Y, Shinya T, Galis I, Arimura GI. Phytohormone-dependent plant defense signaling orchestrated by oral bacteria of the herbivore Spodoptera litura. THE NEW PHYTOLOGIST 2021; 231:2029-2038. [PMID: 33932298 DOI: 10.1111/nph.17444] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 04/23/2021] [Indexed: 06/12/2023]
Abstract
A vast array of herbivorous arthropods live with symbiotic microorganisms. However, little is known about the nature and functional mechanism of bacterial effects on plant defense responses towards herbivores. We explored the role of microbes present in extracts of oral secretion (OS) isolated from larvae of Spodoptera litura, a generalist herbivore, in phytohormone signaling-dependent defense responses in Arabidopsis thaliana (Arabidopsis). In response to mechanical damage (MD) with application of bacteria-free OS (OS- ) prepared by sterilization or filtration of OS, Arabidopsis leaves exhibited enhanced de novo synthesis of oxylipins, and induction of transcript abundance of the responsible genes, in comparison to those in leaves with MD + nonsterilized OS (OS+ ), indicating that OS bacteria serve as suppressors of these genes. By contrast, de novo synthesis/signaling of salicylic acid and signaling of abscisic acid were enhanced by OS bacteria. These signaling networks were cross-regulated by each other. Meta-analysis of OS bacteria identified 70 bacterial strains. Among them was Staphylococcus epidermidis, an anaerobic staphylococcus that was shown to contribute to the suppression/manipulation of phytohormone-dependent plant defense signaling. The presence of OS bacteria was consequently beneficial for S. litura larvae hosted by Brassicaceae.
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Affiliation(s)
- Yukiyo Yamasaki
- Department of Biological Science and Technology, Faculty of Advanced Engineering, Tokyo University of Science, Tokyo, 125-8585, Japan
| | - Hiroka Sumioka
- Department of Biological Science and Technology, Faculty of Advanced Engineering, Tokyo University of Science, Tokyo, 125-8585, Japan
| | - Mayu Takiguchi
- Department of Biological Science and Technology, Faculty of Advanced Engineering, Tokyo University of Science, Tokyo, 125-8585, Japan
| | - Takuya Uemura
- Department of Biological Science and Technology, Faculty of Advanced Engineering, Tokyo University of Science, Tokyo, 125-8585, Japan
| | - Yuka Kihara
- Department of Biological Science and Technology, Faculty of Advanced Engineering, Tokyo University of Science, Tokyo, 125-8585, Japan
| | - Tomonori Shinya
- Institute of Plant Science and Resources (IPSR), Okayama University, Kurashiki, 710-0046, Japan
| | - Ivan Galis
- Institute of Plant Science and Resources (IPSR), Okayama University, Kurashiki, 710-0046, Japan
| | - Gen-Ichiro Arimura
- Department of Biological Science and Technology, Faculty of Advanced Engineering, Tokyo University of Science, Tokyo, 125-8585, Japan
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Paddock KJ, Robert CAM, Erb M, Hibbard BE. Western Corn Rootworm, Plant and Microbe Interactions: A Review and Prospects for New Management Tools. INSECTS 2021; 12:171. [PMID: 33671118 PMCID: PMC7922318 DOI: 10.3390/insects12020171] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 02/11/2021] [Accepted: 02/13/2021] [Indexed: 12/12/2022]
Abstract
The western corn rootworm, Diabrotica virgifera virgifera LeConte, is resistant to four separate classes of traditional insecticides, all Bacillius thuringiensis (Bt) toxins currently registered for commercial use, crop rotation, innate plant resistance factors, and even double-stranded RNA (dsRNA) targeting essential genes via environmental RNA interference (RNAi), which has not been sold commercially to date. Clearly, additional tools are needed as management options. In this review, we discuss the state-of-the-art knowledge about biotic factors influencing herbivore success, including host location and recognition, plant defensive traits, plant-microbe interactions, and herbivore-pathogens/predator interactions. We then translate this knowledge into potential new management tools and improved biological control.
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Affiliation(s)
- Kyle J. Paddock
- Division of Plant Sciences, University of Missouri, Columbia, MO 65211, USA;
| | - Christelle A. M. Robert
- Institute of Plant Sciences, University of Bern, 3013 Bern, Switzerland; (C.A.M.R.); (M.E.)
- Oeschger Centre for Climate Change Research, University of Bern, 3013 Bern, Switzerland
| | - Matthias Erb
- Institute of Plant Sciences, University of Bern, 3013 Bern, Switzerland; (C.A.M.R.); (M.E.)
- Oeschger Centre for Climate Change Research, University of Bern, 3013 Bern, Switzerland
| | - Bruce E. Hibbard
- Plant Genetics Research Unit, United States Department of Agriculture, Agricultural Research Service, Columbia, MO 65211, USA
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7
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Zhu YX, Song ZR, Song YL, Hong XY. Double infection of Wolbachia and Spiroplasma alters induced plant defense and spider mite fecundity. PEST MANAGEMENT SCIENCE 2020; 76:3273-3281. [PMID: 32388920 DOI: 10.1002/ps.5886] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Revised: 04/14/2020] [Accepted: 05/10/2020] [Indexed: 06/11/2023]
Abstract
BACKGROUND Herbivore-associated bacterial symbionts can change plant physiology and influence herbivore fitness. The spider mite Tetranychus truncatus is a notorious pest harboring various bacterial symbionts; however, the effect of bacterial symbionts on host plant physiology remains unclear. Here, we investigated whether infection with the endosymbionts Wolbachia and Spiroplasma altered spider mite performance on tomato plants and affected plant-induced defenses. RESULTS Wolbachia and Spiroplasma were mainly located in the gnathosoma and ovaries of their spider mite hosts. Wolbachia and Spiroplasma significantly improved spider mite reproductive performance in cultivated and wild-type tomato. However, in plants deficient in jasmonic acid (JA) and salicylic acid (SA), there were no significant differences in reproduction between spider mites infected with Wolbachia and Spiroplasma and uninfected mites. The results indicated that the reproduction benefits conferred by endosymbionts may relate to plant defenses. Both spider mites infected with Wolbachia and Spiroplasma and uninfected mites induced similar levels of JA and SA accumulation in tomato, whereas tomato plants damaged by spider mites infected with both Wolbachia and Spiroplasma showed lower expression levels of JA- and SA-responsive genes than those damaged by uninfected spider mites. In addition, mites infected with Wolbachia and Spiroplasma mites consumed more tomato amino acids compared to uninfected spider mites, which may have contributed to host fecundity. CONCLUSIONS Our results suggest that the reproduction benefits conferred by endosymbionts may be associated with changes in plant defense parameters and the concentrations of plant amino acids. The results highlight the importance of endosymbionts in interactions between spider mites and their host plants. © 2020 Society of Chemical Industry.
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Affiliation(s)
- Yu-Xi Zhu
- Department of Entomology, Nanjing Agricultural University, Nanjing, China
| | - Zhang-Rong Song
- Department of Entomology, Nanjing Agricultural University, Nanjing, China
| | - Yue-Ling Song
- Department of Entomology, Nanjing Agricultural University, Nanjing, China
| | - Xiao-Yue Hong
- Department of Entomology, Nanjing Agricultural University, Nanjing, China
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Grunseich JM, Thompson MN, Hay AA, Gorman Z, Kolomiets MV, Eubanks MD, Helms AM. Risky roots and careful herbivores: Sustained herbivory by a root‐feeding herbivore attenuates indirect plant defences. Funct Ecol 2020. [DOI: 10.1111/1365-2435.13627] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- John M. Grunseich
- Department of Entomology Texas A&M University College Station TX USA
| | | | - Allison A. Hay
- Department of Entomology Texas A&M University College Station TX USA
| | - Zachary Gorman
- Department of Plant Pathology and Microbiology Texas A&M University College Station TX USA
| | - Michael V. Kolomiets
- Department of Plant Pathology and Microbiology Texas A&M University College Station TX USA
| | - Micky D. Eubanks
- Department of Entomology Texas A&M University College Station TX USA
| | - Anjel M. Helms
- Department of Entomology Texas A&M University College Station TX USA
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9
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Zélé F, Santos JL, Godinho DP, Magalhães S. Wolbachia both aids and hampers the performance of spider mites on different host plants. FEMS Microbiol Ecol 2018; 94:5097780. [DOI: 10.1093/femsec/fiy187] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 09/12/2018] [Indexed: 11/14/2022] Open
Affiliation(s)
- Flore Zélé
- cE3c: Centre for Ecology, Evolution and Environmental Changes, Faculdade de Ciěncias da Universidade de Lisboa, Edificio C2, Piso-3, Campo Grande, 1749-016 Lisbon, Portugal
| | - Joaquim L Santos
- cE3c: Centre for Ecology, Evolution and Environmental Changes, Faculdade de Ciěncias da Universidade de Lisboa, Edificio C2, Piso-3, Campo Grande, 1749-016 Lisbon, Portugal
| | - Diogo P Godinho
- cE3c: Centre for Ecology, Evolution and Environmental Changes, Faculdade de Ciěncias da Universidade de Lisboa, Edificio C2, Piso-3, Campo Grande, 1749-016 Lisbon, Portugal
| | - Sara Magalhães
- cE3c: Centre for Ecology, Evolution and Environmental Changes, Faculdade de Ciěncias da Universidade de Lisboa, Edificio C2, Piso-3, Campo Grande, 1749-016 Lisbon, Portugal
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10
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Schausberger P. Herbivore-Associated Bacteria as Potential Mediators and Modifiers of Induced Plant Defense Against Spider Mites and Thrips. FRONTIERS IN PLANT SCIENCE 2018; 9:1107. [PMID: 30105044 PMCID: PMC6077224 DOI: 10.3389/fpls.2018.01107] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Accepted: 07/09/2018] [Indexed: 05/13/2023]
Abstract
Induced plant defense, comprising contact with exogenous stimuli, production of endogenous signals alerting the plant, associated biochemical cascades, and local and/or systemic expression of the defense mechanisms, critically depends on the nature of the inducing agents. At large, bio-trophic pathogenic microorganisms and viruses usually trigger the salicylate (SA)-mediated pathway, whereas necro-trophic pathogens and herbivores usually trigger the jasmonate (JA)-mediated pathway in plants. The SA- and JA-mediated pathways do not operate independently but commonly interfere with each other. Several recent studies revealed abnormal plant responses upon herbivore attack in diverse plant-herbivore systems. Observed abnormalities range from suppression of the common JA-pathway, induction of the SA-pathway to no response, yet the underlying proximate causes and ultimate consequences of these variations are elusive. Strikingly, some studies provide compelling evidence that anti-herbivore plant responses may decisively depend on bacteria associated with the herbivore attacking the plant (HAB for herbivore-associated bacteria). HAB may influence herbivore recognition by the plant and alter the biochemical cascades inside plants. Here, I report cases in point of HAB manipulating induced anti-herbivore plant responses, suggest spatial and temporal categorization of HAB, and point at proximate and ultimate aspects of plant defense manipulation by HAB. Following, I overview the diversity of HAB of spider mites and herbivorous thrips, argue that, considering recently reported phenomena of abnormal plant responses upon spider mite attack, some of these HAB could represent important, but hitherto largely neglected, mediators/modifiers of induced plant defense against spider mites and thrips, and conclude with suggestions for future research.
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Affiliation(s)
- Peter Schausberger
- Department of Behavioural Biology, University of Vienna, Vienna, Austria
- Sugadaira Research Station, Mountain Science Center, University of Tsukuba, Ueda, Japan
- *Correspondence: Peter Schausberger,
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Basu S, Varsani S, Louis J. Altering Plant Defenses: Herbivore-Associated Molecular Patterns and Effector Arsenal of Chewing Herbivores. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2018; 31:13-21. [PMID: 28840787 DOI: 10.1094/mpmi-07-17-0183-fi] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Chewing herbivores, such as caterpillars and beetles, while feeding on the host plant, cause extensive tissue damage and release a wide array of cues to alter plant defenses. Consequently, the cues can have both beneficial and detrimental impacts on the chewing herbivores. Herbivore-associated molecular patterns (HAMPs) are molecules produced by herbivorous insects that aid them to elicit plant defenses leading to impairment of insect growth, while effectors suppress plant defenses and contribute to increased susceptibility to subsequent feeding by chewing herbivores. Besides secretions that originate from glands (e.g., saliva) and fore- and midgut regions (e.g., oral secretions) of chewing herbivores, recent studies have shown that insect frass and herbivore-associated endosymbionts also play a critical role in modulating plant defenses. In this review, we provide an update on a growing body of literature that discusses the chewing insect HAMPs and effectors and the mechanisms by which they modulate host defenses. Novel "omic" approaches and availability of new tools will help researchers to move forward this discipline by identifying and characterizing novel insect HAMPs and effectors and how these herbivore-associated cues are perceived by host plant receptors.
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Affiliation(s)
| | | | - Joe Louis
- 1 Department of Entomology; and
- 2 Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, NE 68583, U.S.A
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Independent Effects of a Herbivore's Bacterial Symbionts on Its Performance and Induced Plant Defences. Int J Mol Sci 2017; 18:ijms18010182. [PMID: 28106771 PMCID: PMC5297814 DOI: 10.3390/ijms18010182] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 12/10/2016] [Accepted: 01/10/2017] [Indexed: 01/23/2023] Open
Abstract
It is well known that microbial pathogens and herbivores elicit defence responses in plants. Moreover, microorganisms associated with herbivores, such as bacteria or viruses, can modulate the plant’s response to herbivores. Herbivorous spider mites can harbour different species of bacterial symbionts and exert a broad range of effects on host-plant defences. Hence, we tested the extent to which such symbionts affect the plant’s defences induced by their mite host and assessed if this translates into changes in plant resistance. We assessed the bacterial communities of two strains of the common mite pest Tetranychus urticae. We found that these strains harboured distinct symbiotic bacteria and removed these using antibiotics. Subsequently, we tested to which extent mites with and without symbiotic bacteria induce plant defences in terms of phytohormone accumulation and defence gene expression, and assessed mite oviposition and survival as a measure for plant resistance. We observed that the absence/presence of these bacteria altered distinct plant defence parameters and affected mite performance but we did not find indications for a causal link between the two. We argue that although bacteria-related effects on host-induced plant defences may occur, these do not necessarily affect plant resistance concomitantly.
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Wang J, Chung SH, Peiffer M, Rosa C, Hoover K, Zeng R, Felton GW. Herbivore Oral Secreted Bacteria Trigger Distinct Defense Responses in Preferred and Non-Preferred Host Plants. J Chem Ecol 2016; 42:463-74. [PMID: 27294415 DOI: 10.1007/s10886-016-0712-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Revised: 05/08/2016] [Accepted: 05/28/2016] [Indexed: 11/30/2022]
Abstract
Insect symbiotic bacteria affect host physiology and mediate plant-insect interactions, yet there are few clear examples of symbiotic bacteria regulating defense responses in different host plants. We hypothesized that plants would induce distinct defense responses to herbivore- associated bacteria. We evaluated whether preferred hosts (horsenettle) or non-preferred hosts (tomato) respond similarly to oral secretions (OS) from the false potato beetle (FPB, Leptinotarsa juncta), and whether the induced defense triggered by OS was due to the presence of symbiotic bacteria in OS. Both horsenettle and tomato damaged by antibiotic (AB) treated larvae showed higher polyphenol oxidase (PPO) activity than those damaged by non-AB treated larvae. In addition, application of OS from AB treated larvae induced higher PPO activity compared with OS from non-AB treated larvae or water treatment. False potato beetles harbor bacteria that may provide abundant cues that can be recognized by plants and thus mediate corresponding defense responses. Among all tested bacterial isolates, the genera Pantoea, Acinetobacter, Enterobacter, and Serratia were found to suppress PPO activity in tomato, while only Pantoea sp. among these four isolates was observed to suppress PPO activity in horsenettle. The distinct PPO suppression caused by symbiotic bacteria in different plants was similar to the pattern of induced defense-related gene expression. Pantoea inoculated FPB suppressed JA-responsive genes and triggered a SA-responsive gene in both tomato and horsenettle. However, Enterobacter inoculated FPB eliminated JA-regulated gene expression and elevated SA-regulated gene expression in tomato, but did not show evident effects on the expression levels of horsenettle defense-related genes. These results indicate that suppression of plant defenses by the bacteria found in the oral secretions of herbivores may be a more widespread phenomenon than previously indicated.
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Affiliation(s)
- Jie Wang
- Department of Ecology, South China Agricultural University, Guangzhou, Guangdong, 510640, China. .,Department of Entomology, Pennsylvania State University, University Park, PA, 16802, USA.
| | - Seung Ho Chung
- Department of Entomology, Cornell University, Ithaca, NY, 14850, USA
| | - Michelle Peiffer
- Department of Entomology, Pennsylvania State University, University Park, PA, 16802, USA
| | - Cristina Rosa
- Department of Plant Pathology and Environmental Microbiology, Pennsylvania State University, University Park, PA, 16802, USA
| | - Kelli Hoover
- Department of Entomology, Pennsylvania State University, University Park, PA, 16802, USA
| | - Rensen Zeng
- Department of Ecology, South China Agricultural University, Guangzhou, Guangdong, 510640, China.,Department of Ecology, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China
| | - Gary W Felton
- Department of Entomology, Pennsylvania State University, University Park, PA, 16802, USA
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14
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Giron D, Huguet E, Stone GN, Body M. Insect-induced effects on plants and possible effectors used by galling and leaf-mining insects to manipulate their host-plant. JOURNAL OF INSECT PHYSIOLOGY 2016; 84:70-89. [PMID: 26723843 DOI: 10.1016/j.jinsphys.2015.12.009] [Citation(s) in RCA: 121] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Revised: 12/21/2015] [Accepted: 12/22/2015] [Indexed: 05/04/2023]
Abstract
Gall-inducing insects are iconic examples in the manipulation and reprogramming of plant development, inducing spectacular morphological and physiological changes of host-plant tissues within which the insect feeds and grows. Despite decades of research, effectors involved in gall induction and basic mechanisms of gall formation remain unknown. Recent research suggests that some aspects of the plant manipulation shown by gall-inducers may be shared with other insect herbivorous life histories. Here, we illustrate similarities and contrasts by reviewing current knowledge of metabolic and morphological effects induced on plants by gall-inducing and leaf-mining insects, and ask whether leaf-miners can also be considered to be plant reprogrammers. We review key plant functions targeted by various plant reprogrammers, including plant-manipulating insects and nematodes, and functionally characterize insect herbivore-derived effectors to provide a broader understanding of possible mechanisms used in host-plant manipulation. Consequences of plant reprogramming in terms of ecology, coevolution and diversification of plant-manipulating insects are also discussed.
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Affiliation(s)
- David Giron
- Institut de Recherche sur la Biologie de l'Insecte, UMR 7261, CNRS/Université François-Rabelais de Tours, Parc Grandmont, 37200 Tours, France.
| | - Elisabeth Huguet
- Institut de Recherche sur la Biologie de l'Insecte, UMR 7261, CNRS/Université François-Rabelais de Tours, Parc Grandmont, 37200 Tours, France
| | - Graham N Stone
- Institute of Evolutionary Biology, University of Edinburgh, Edinburgh EH9 3JT, United Kingdom
| | - Mélanie Body
- Division of Plant Sciences, Christopher S. Bond Life Sciences Center, 1201 Rollins Street, University of Missouri, Columbia, MO 65211, United States
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15
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Gutzwiller F, Dedeine F, Kaiser W, Giron D, Lopez-Vaamonde C. Correlation between the green-island phenotype and Wolbachia infections during the evolutionary diversification of Gracillariidae leaf-mining moths. Ecol Evol 2015; 5:4049-62. [PMID: 26442762 PMCID: PMC4588643 DOI: 10.1002/ece3.1580] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Revised: 05/29/2015] [Accepted: 06/03/2015] [Indexed: 02/05/2023] Open
Abstract
Internally feeding herbivorous insects such as leaf miners have developed the ability to manipulate the physiology of their host plants in a way to best meet their metabolic needs and compensate for variation in food nutritional composition. For instance, some leaf miners can induce green-islands on yellow leaves in autumn, which are characterized by photosynthetically active green patches in otherwise senescing leaves. It has been shown that endosymbionts, and most likely bacteria of the genus Wolbachia, play an important role in green-island induction in the apple leaf-mining moth Phyllonorycter blancardella. However, it is currently not known how widespread is this moth-Wolbachia-plant interaction. Here, we studied the co-occurrence between Wolbachia and the green-island phenotype in 133 moth specimens belonging to 74 species of Lepidoptera including 60 Gracillariidae leaf miners. Using a combination of molecular phylogenies and ecological data (occurrence of green-islands), we show that the acquisitions of the green-island phenotype and Wolbachia infections have been associated through the evolutionary diversification of Gracillariidae. We also found intraspecific variability in both green-island formation and Wolbachia infection, with some species being able to form green-islands without being infected by Wolbachia. In addition, Wolbachia variants belonging to both A and B supergroups were found to be associated with green-island phenotype suggesting several independent origins of green-island induction. This study opens new prospects and raises new questions about the ecology and evolution of the tripartite association between Wolbachia, leaf miners, and their host plants.
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Affiliation(s)
| | - Franck Dedeine
- IRBI UMR 7261 CNRS/Université François-Rabelais de Tours 37200 Tours France
| | - Wilfried Kaiser
- IRBI UMR 7261 CNRS/Université François-Rabelais de Tours 37200 Tours France
| | - David Giron
- IRBI UMR 7261 CNRS/Université François-Rabelais de Tours 37200 Tours France
| | - Carlos Lopez-Vaamonde
- IRBI UMR 7261 CNRS/Université François-Rabelais de Tours 37200 Tours France ; INRA UR0633 Zoologie Forestière F-45075 Orléans France
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16
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Krawczyk K, Szymańczyk M, Obrępalska-Stęplowska A. Prevalence of Endosymbionts in Polish Populations of Leptinotarsa decemlineata (Coleoptera: Chrysomelidae). JOURNAL OF INSECT SCIENCE (ONLINE) 2015; 15:iev085. [PMID: 26206894 PMCID: PMC4672246 DOI: 10.1093/jisesa/iev085] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Accepted: 07/02/2015] [Indexed: 05/30/2023]
Abstract
Colorado potato beetle (CPB, Leptinotarsa decemlineata Say) (Coleoptera: Chrysomelidae) is one of the most serious insect pest feeding on wild and cultivated Solanaceae plants. This pest poses a significant threat to potato crops. CPB originated from North America but has become widespread and has adapted in new localizations. Currently, it is reported in many countries worldwide. Endosymbiotic bacteria might have an influence on insect adaptation to new conditions. They are known to play a role in invasiveness of insect hosts and to facilitate colonization of new niches; however, information on endosymbionts of the CPB is very limited. In this study, we screened CPB populations collected from 20 evenly distributed locations in Poland for the presence of Arsenophonus, Cardinium, Wolbachia, and Flavobacterium. We found the presence of Flavobacterium in the studied insects. Little is known about CPB-endosymbionts interactions, thus this study may provide a reference for future studies in this subject.
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Affiliation(s)
- Krzysztof Krawczyk
- Virology and Bacteriology Department, Institute of Plant Protection-National research Institute, 20 Władysława Węgorka St, 60-310 Poznań, Poland
| | - Mateusz Szymańczyk
- Department of Weed Science and Plant Protection Techniques, Institute of Plant Protection-National research Institute, 20 Władysława Węgorka St, 60-310 Poznań, Poland
| | - Aleksandra Obrępalska-Stęplowska
- Interdepartmental Laboratory of Molecular Biology, Institute of Plant Protection-National research Institute, 20 Władysława Węgorka St, 60-310 Poznań, Poland
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17
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Su Q, Oliver KM, Xie W, Wu Q, Wang S, Zhang Y. The whitefly‐associated facultative symbiont
Hamiltonella defensa
suppresses induced plant defences in tomato. Funct Ecol 2015. [DOI: 10.1111/1365-2435.12405] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Qi Su
- Department of Plant Protection Institute of Vegetables and Flowers Chinese Academy of Agricultural Sciences Beijing 100081 China
- College of Plant Protection Hunan Agricultural University Changsha Hunan 410128 China
| | - Kerry M. Oliver
- Department of Entomology University of Georgia Athens GA 30602 USA
| | - Wen Xie
- Department of Plant Protection Institute of Vegetables and Flowers Chinese Academy of Agricultural Sciences Beijing 100081 China
| | - Qingjun Wu
- Department of Plant Protection Institute of Vegetables and Flowers Chinese Academy of Agricultural Sciences Beijing 100081 China
| | - Shaoli Wang
- Department of Plant Protection Institute of Vegetables and Flowers Chinese Academy of Agricultural Sciences Beijing 100081 China
| | - Youjun Zhang
- Department of Plant Protection Institute of Vegetables and Flowers Chinese Academy of Agricultural Sciences Beijing 100081 China
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18
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Sugio A, Dubreuil G, Giron D, Simon JC. Plant-insect interactions under bacterial influence: ecological implications and underlying mechanisms. JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:467-78. [PMID: 25385767 DOI: 10.1093/jxb/eru435] [Citation(s) in RCA: 91] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Plants and insects have been co-existing for more than 400 million years, leading to intimate and complex relationships. Throughout their own evolutionary history, plants and insects have also established intricate and very diverse relationships with microbial associates. Studies in recent years have revealed plant- or insect-associated microbes to be instrumental in plant-insect interactions, with important implications for plant defences and plant utilization by insects. Microbial communities associated with plants are rich in diversity, and their structure greatly differs between below- and above-ground levels. Microbial communities associated with insect herbivores generally present a lower diversity and can reside in different body parts of their hosts including bacteriocytes, haemolymph, gut, and salivary glands. Acquisition of microbial communities by vertical or horizontal transmission and possible genetic exchanges through lateral transfer could strongly impact on the host insect or plant fitness by conferring adaptations to new habitats. Recent developments in sequencing technologies and molecular tools have dramatically enhanced opportunities to characterize the microbial diversity associated with plants and insects and have unveiled some of the mechanisms by which symbionts modulate plant-insect interactions. Here, we focus on the diversity and ecological consequences of bacterial communities associated with plants and herbivorous insects. We also highlight the known mechanisms by which these microbes interfere with plant-insect interactions. Revealing such mechanisms in model systems under controlled environments but also in more natural ecological settings will help us to understand the evolution of complex multitrophic interactions in which plants, herbivorous insects, and micro-organisms are inserted.
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Affiliation(s)
- Akiko Sugio
- INRA, Institut de Génétique, Environnement et Protection des Plantes, UMR 1349 IGEPP, Domaine de la Motte, 35653 Le Rheu Cedex, France
| | - Géraldine Dubreuil
- Institut de Recherche sur la Biologie de l'Insecte, UMR 7261 CNRS / Université François-Rabelais, UFR Sciences et Techniques, Parc de Grandmont, 37200 Tours, France
| | - David Giron
- Institut de Recherche sur la Biologie de l'Insecte, UMR 7261 CNRS / Université François-Rabelais, UFR Sciences et Techniques, Parc de Grandmont, 37200 Tours, France
| | - Jean-Christophe Simon
- INRA, Institut de Génétique, Environnement et Protection des Plantes, UMR 1349 IGEPP, Domaine de la Motte, 35653 Le Rheu Cedex, France
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19
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Johnson SN, Rasmann S. Root-feeding insects and their interactions with organisms in the rhizosphere. ANNUAL REVIEW OF ENTOMOLOGY 2015; 60:517-35. [PMID: 25564744 DOI: 10.1146/annurev-ento-010814-020608] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Root-feeding insects are an increasingly studied group of herbivores whose impacts on plant productivity and ecosystem processes are widely recognized. Their belowground habitat has hitherto hindered our understanding of how they interact with other organisms that share the rhizosphere. A surge in research in this area has now shed light on these interactions. We review key interactions between root-feeding insects and other rhizospheric organisms, including beneficial plant microbes (mycorrhizal fungi, nitrogen-fixing bacteria), antagonists/pathogens of root herbivores (arthropod predators, entomopathogenic nematodes/fungi, and bacterial pathogens), competitors, symbiotic microbes, and detritivores. Patterns for these interactions are emerging. The negative impacts of mycorrhizal fungi on root herbivores, for instance, raise the intriguing prospect that these fungi could be used for pest management. Moreover, a better understanding of symbiotic microbes in root herbivores, especially those underpinning digestion, could prove useful in industries such as biofuel production.
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Affiliation(s)
- Scott N Johnson
- Hawkesbury Institute for the Environment, University of Western Sydney, Penrith NSW 2751, Australia;
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20
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Evaluating Insect-Microbiomes at the Plant-Insect Interface. J Chem Ecol 2014; 40:836-47. [DOI: 10.1007/s10886-014-0475-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Revised: 06/17/2014] [Accepted: 06/20/2014] [Indexed: 12/17/2022]
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21
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Cytokinin-induced phenotypes in plant-insect interactions: learning from the bacterial world. J Chem Ecol 2014; 40:826-35. [PMID: 24944001 DOI: 10.1007/s10886-014-0466-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Revised: 06/02/2014] [Accepted: 06/05/2014] [Indexed: 01/09/2023]
Abstract
Recently, a renewed interest in cytokinins (CKs) has allowed the characterization of these phytohormones as key regulatory molecules in plant biotic interactions. They have been proved to be instrumental in microbe- and insect-mediated plant phenotypes that can be either beneficial or detrimental for the host-plant. In parallel, insect endosymbiotic bacteria have emerged as key players in plant-insect interactions mediating directly or indirectly fundamental aspects of insect nutrition, such as insect feeding efficiency or the ability to manipulate plant physiology to overcome food nutritional imbalances. However, mechanisms that regulate CK production and the role played by insects and their endosymbionts remain largely unknown. Against this backdrop, studies on plant-associated bacteria have revealed fascinating and complex molecular mechanisms that lead to the production of bacterial CKs and the modulation of plant-borne CKs which ultimately result in profound metabolic and morphological plant modifications. This review highlights major strategies used by plant-associated bacteria that impact the CK homeostasis of their host-plant, to raise parallels with strategies used by phytophagous insects and to discuss the possible role played by endosymbiotic bacteria in these CK-mediated plant phenotypes. We hypothesize that insects employ a CK-mix production strategy that manipulates the phytohormonal balance of their host-plant and overtakes plant gene expression causing a metabolic and morphological habitat modification. In addition, insect endosymbiotic bacteria may prove to be instrumental in these manipulations through the production of bacterial CKs, including specific forms that challenge the CK-degrading capacity of the plant (thus ensuring persistent effects) and the CK-mediated plant defenses.
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22
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Zug R, Hammerstein P. Bad guys turned nice? A critical assessment of Wolbachia mutualisms in arthropod hosts. Biol Rev Camb Philos Soc 2014; 90:89-111. [PMID: 24618033 DOI: 10.1111/brv.12098] [Citation(s) in RCA: 191] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Revised: 02/05/2014] [Accepted: 02/07/2014] [Indexed: 12/21/2022]
Abstract
Wolbachia are the most abundant bacterial endosymbionts among arthropods. Although maternally inherited, they do not conform to the widespread view that vertical transmission inevitably selects for beneficial symbionts. Instead, Wolbachia are notorious for their reproductive parasitism which, although lowering host fitness, ensures their spread. However, even for reproductive parasites it can pay to enhance host fitness. Indeed, there is a recent upsurge of reports on Wolbachia-associated fitness benefits. Therefore, the question arises how such instances of mutualism are related to the phenotypes of reproductive parasitism. Here, we review the evidence of Wolbachia mutualisms in arthropods, including both facultative and obligate relationships, and critically assess their biological relevance. Although many studies report anti-pathogenic effects of Wolbachia, few actually prove these effects to be relevant to field conditions. We further show that Wolbachia frequently have beneficial and detrimental effects at the same time, and that reproductive manipulations and obligate mutualisms may share common mechanisms. These findings undermine the idea of a clear-cut distinction between Wolbachia mutualism and parasitism. In general, both facultative and obligate mutualisms can have a strong, and sometimes unforeseen, impact on the ecology and evolution of Wolbachia and their arthropod hosts. Acknowledging this mutualistic potential might be the key to a better understanding of some unresolved issues in the study of Wolbachia-host interactions.
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Affiliation(s)
- Roman Zug
- Institute for Theoretical Biology, Humboldt-Universität zu Berlin, Invalidenstr. 43, 10115, Berlin, Germany
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23
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Herbivore exploits orally secreted bacteria to suppress plant defenses. Proc Natl Acad Sci U S A 2013; 110:15728-33. [PMID: 24019469 DOI: 10.1073/pnas.1308867110] [Citation(s) in RCA: 270] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Induced plant defenses in response to herbivore attack are modulated by cross-talk between jasmonic acid (JA)- and salicylic acid (SA)-signaling pathways. Oral secretions from some insect herbivores contain effectors that overcome these antiherbivore defenses. Herbivores possess diverse microbes in their digestive systems and these microbial symbionts can modify plant-insect interactions; however, the specific role of herbivore-associated microbes in manipulating plant defenses remains unclear. Here, we demonstrate that Colorado potato beetle (Leptinotarsa decemlineata) larvae exploit bacteria in their oral secretions to suppress antiherbivore defenses in tomato (Solanum lycopersicum). We found that antibiotic-untreated larvae decreased production of JA and JA-responsive antiherbivore defenses, but increased SA accumulation and SA-responsive gene expression. Beetles benefit from down-regulating plant defenses by exhibiting enhanced larval growth. In SA-deficient plants, suppression was not observed, indicating that suppression of JA-regulated defenses depends on the SA-signaling pathway. Applying bacteria isolated from larval oral secretions to wounded plants confirmed that three microbial symbionts belonging to the genera Stenotrophomonas, Pseudomonas, and Enterobacter are responsible for defense suppression. Additionally, reinoculation of these bacteria to antibiotic-treated larvae restored their ability to suppress defenses. Flagellin isolated from Pseudomonas sp. was associated with defense suppression. Our findings show that the herbivore exploits symbiotic bacteria as a decoy to deceive plants into incorrectly perceiving the threat as microbial. By interfering with the normal perception of herbivory, beetles can evade antiherbivore defenses of its host.
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