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Epichloë Endophytes Alter Inducible Indirect Defences in Host Grasses

Epichloë endophytes are common symbionts living asymptomatically in pooid grasses and may provide chemical defences against herbivorous insects. While the mechanisms underlying these fungal defences have been well studied, it remains unknown whether endophyte presence affects the host's own def...

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Autores principales: Li, Tao, Blande, James D., Gundel, Pedro E., Helander, Marjo, Saikkonen, Kari
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2014
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4076332/
https://www.ncbi.nlm.nih.gov/pubmed/24978701
http://dx.doi.org/10.1371/journal.pone.0101331
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author Li, Tao
Blande, James D.
Gundel, Pedro E.
Helander, Marjo
Saikkonen, Kari
author_facet Li, Tao
Blande, James D.
Gundel, Pedro E.
Helander, Marjo
Saikkonen, Kari
author_sort Li, Tao
collection PubMed
description Epichloë endophytes are common symbionts living asymptomatically in pooid grasses and may provide chemical defences against herbivorous insects. While the mechanisms underlying these fungal defences have been well studied, it remains unknown whether endophyte presence affects the host's own defences. We addressed this issue by examining variation in the impact of Epichloë on constitutive and herbivore-induced emissions of volatile organic compounds (VOC), a well-known indirect plant defence, between two grass species, Schedonorus phoenix (ex. Festuca arundinacea; tall fescue) and Festuca pratensis (meadow fescue). We found that feeding by a generalist aphid species, Rhopalosiphum padi, induced VOC emissions by uninfected plants of both grass species but to varying extents, while mechanical wounding failed to do so in both species after one day of damage. Interestingly, regardless of damage treatment, Epichloë uncinata-infected F. pratensis emitted significantly lower quantities of VOCs than their uninfected counterparts. In contrast, Epichloë coenophiala-infected S. phoenix did not differ from their uninfected counterparts in constitutive VOC emissions but tended to increase VOC emissions under intense aphid feeding. A multivariate analysis showed that endophyte status imposed stronger differences in VOC profiles of F. pratensis than damage treatment, while the reverse was true for S. phoenix. Additionally, both endophytes inhibited R. padi population growth as measured by aphid dry biomass, with the inhibition appearing greater in E. uncinata-infected F. pratensis. Our results suggest, not only that Epichloë endophytes may play important roles in mediating host VOC responses to herbivory, but also that the magnitude and direction of such responses may vary with the identity of the Epichloë–grass symbiosis. Whether Epichloë-mediated host VOC responses will eventually translate into effects on higher trophic levels merits future investigation.
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spelling pubmed-40763322014-07-02 Epichloë Endophytes Alter Inducible Indirect Defences in Host Grasses Li, Tao Blande, James D. Gundel, Pedro E. Helander, Marjo Saikkonen, Kari PLoS One Research Article Epichloë endophytes are common symbionts living asymptomatically in pooid grasses and may provide chemical defences against herbivorous insects. While the mechanisms underlying these fungal defences have been well studied, it remains unknown whether endophyte presence affects the host's own defences. We addressed this issue by examining variation in the impact of Epichloë on constitutive and herbivore-induced emissions of volatile organic compounds (VOC), a well-known indirect plant defence, between two grass species, Schedonorus phoenix (ex. Festuca arundinacea; tall fescue) and Festuca pratensis (meadow fescue). We found that feeding by a generalist aphid species, Rhopalosiphum padi, induced VOC emissions by uninfected plants of both grass species but to varying extents, while mechanical wounding failed to do so in both species after one day of damage. Interestingly, regardless of damage treatment, Epichloë uncinata-infected F. pratensis emitted significantly lower quantities of VOCs than their uninfected counterparts. In contrast, Epichloë coenophiala-infected S. phoenix did not differ from their uninfected counterparts in constitutive VOC emissions but tended to increase VOC emissions under intense aphid feeding. A multivariate analysis showed that endophyte status imposed stronger differences in VOC profiles of F. pratensis than damage treatment, while the reverse was true for S. phoenix. Additionally, both endophytes inhibited R. padi population growth as measured by aphid dry biomass, with the inhibition appearing greater in E. uncinata-infected F. pratensis. Our results suggest, not only that Epichloë endophytes may play important roles in mediating host VOC responses to herbivory, but also that the magnitude and direction of such responses may vary with the identity of the Epichloë–grass symbiosis. Whether Epichloë-mediated host VOC responses will eventually translate into effects on higher trophic levels merits future investigation. Public Library of Science 2014-06-30 /pmc/articles/PMC4076332/ /pubmed/24978701 http://dx.doi.org/10.1371/journal.pone.0101331 Text en © 2014 Li et al http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited.
spellingShingle Research Article
Li, Tao
Blande, James D.
Gundel, Pedro E.
Helander, Marjo
Saikkonen, Kari
Epichloë Endophytes Alter Inducible Indirect Defences in Host Grasses
title Epichloë Endophytes Alter Inducible Indirect Defences in Host Grasses
title_full Epichloë Endophytes Alter Inducible Indirect Defences in Host Grasses
title_fullStr Epichloë Endophytes Alter Inducible Indirect Defences in Host Grasses
title_full_unstemmed Epichloë Endophytes Alter Inducible Indirect Defences in Host Grasses
title_short Epichloë Endophytes Alter Inducible Indirect Defences in Host Grasses
title_sort epichloë endophytes alter inducible indirect defences in host grasses
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4076332/
https://www.ncbi.nlm.nih.gov/pubmed/24978701
http://dx.doi.org/10.1371/journal.pone.0101331
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