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Dearing MD, Kaltenpoth M, Gershenzon J. Demonstrating the role of symbionts in mediating detoxification in herbivores. Symbiosis 2022; 87:59-66. [PMID: 36164313 PMCID: PMC9499882 DOI: 10.1007/s13199-022-00863-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Accepted: 07/23/2022] [Indexed: 11/30/2022]
Abstract
AbstractPlant toxins constitute an effective defense against herbivorous animals. However, many herbivores have evolved adaptations to cope with dietary toxins through detoxification, excretion, sequestration, target site insensitivity and/or via behavioral avoidance. While these adaptations are often directly encoded in herbivore genomes, evidence is accumulating that microbial symbionts can reduce the dose of plant toxins by metabolizing or sequestering them prior to absorption by the herbivore. Here, we describe a few well-studied examples to assess such symbiont-mediated detoxification and showcase different approaches that have been used for their analyses. These include: (i) a host phenotypic route in which the symbiotic association is manipulated to reveal host fitness costs upon toxin exposure in the presence/absence of detoxifying symbionts, including function restoration after symbiont re-infection, (ii) a molecular microbiological approach that focuses on the identification and characterization of microbial genes involved in plant toxin metabolism, and (iii) an analytical chemical route that aims to characterize the conversion of the toxin to less harmful metabolites in vivo and link conversion to the activities of a detoxifying symbiont. The advantages and challenges of each approach are discussed, and it is argued that a multi-pronged strategy combining phenotypic, molecular, and chemical evidence is needed to unambiguously demonstrate microbial contributions to plant toxin reduction and the importance of these processes for host fitness. Given the interdisciplinary nature of the topic, we aim to provide a guideline to researchers interested in symbiont-mediated detoxification and hope to encourage future studies that contribute to a more comprehensive and mechanistic understanding of detoxification in herbivores and their symbionts.
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Affiliation(s)
- M. Denise Dearing
- School of Biological Sciences, University of Utah, Salt Lake City, UT 84112 USA
- Department of Biochemistry, Max Planck Institute for Chemical Ecology, Hans-Knöll-Str. 8, 07745 Jena, Germany
| | - Martin Kaltenpoth
- Department of Insect Symbiosis, Max Planck Institute for Chemical Ecology, Hans-Knöll-Str.8, 07745 Jena, Germany
| | - Jonathan Gershenzon
- Department of Biochemistry, Max Planck Institute for Chemical Ecology, Hans-Knöll-Str. 8, 07745 Jena, Germany
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