Dataset Information

Specificity in Mesograzer-Induced Defences in Seagrasses.

ABSTRACT: Grazing-induced plant defences that reduce palatability to herbivores are widespread in terrestrial plants and seaweeds, but they have not yet been reported in seagrasses. We investigated the ability of two seagrass species to induce defences in response to direct grazing by three associated mesograzers. Specifically, we conducted feeding-assayed induction experiments to examine how mesograzer-specific grazing impact affects seagrass induction of defences within the context of the optimal defence theory. We found that the amphipod Gammarus insensibilis and the isopod Idotea chelipes exerted a low-intensity grazing on older blades of the seagrass Cymodocea nodosa, which reflects a weak grazing impact that may explain the lack of inducible defences. The isopod Synischia hectica exerted the strongest grazing impact on C. nodosa via high-intensity feeding on young blades with a higher fitness value. This isopod grazing induced defences in C. nodosa as indicated by a consistently lower consumption of blades previously grazed for 5, 12 and 16 days. The lower consumption was maintained when offered tissues with no plant structure (agar-reconstituted food), but showing a reduced size of the previous grazing effect. This indicates that structural traits act in combination with chemical traits to reduce seagrass palatability to the isopod. Increase in total phenolics but not in C:N ratio and total nitrogen of grazed C. nodosa suggests chemical defences rather than a modified nutritional quality as primarily induced chemical traits. We detected no induction of defences in Zostera noltei, which showed the ability to replace moderate losses of young biomass to mesograzers via compensatory growth. Our study provides the first experimental evidence of induction of defences against meso-herbivory that reduce further consumption in seagrasses. It also emphasizes the relevance of grazer identity in determining the level of grazing impact triggering resistance and compensatory responses of different seagrass species.

SUBMITTER: Martinez-Crego B

PROVIDER: S-EPMC4624237 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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Publications

Specificity in Mesograzer-Induced Defences in Seagrasses.

Martínez-Crego Begoña B Arteaga Pedro P Ueber Alexandra A Engelen Aschwin H AH Santos Rui R Molis Markus M

PloS one 20151027 10

Grazing-induced plant defences that reduce palatability to herbivores are widespread in terrestrial plants and seaweeds, but they have not yet been reported in seagrasses. We investigated the ability of two seagrass species to induce defences in response to direct grazing by three associated mesograzers. Specifically, we conducted feeding-assayed induction experiments to examine how mesograzer-specific grazing impact affects seagrass induction of defences within the context of the optimal defenc ...[more]

PMID: 26506103

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Project description:Herbivore-induced defence responses are often specific - different herbivores induce different defence responses in plants - and their specificity is largely mediated by chemical cues (herbivore-associated elicitors: HAEs) in insect oral or oviposition secretions. However, the specificity and the mechanisms of HAE-induced defence have not been investigated in the context of the evolutionary relationships among plant species. Here we compare the responses of six closely related Nicotiana species to a synthetic elicitor, N-linolenoyl-glutamic acid (C18:3-Glu) and HAE of two insect herbivores (the Solanaceae specialist Manduca sexta and generalist Spodoptera littoralis).HAE-induced defences are highly specific among closely related Nicotiana species at three perspectives. 1) A single Nicotiana species can elicit distinct responses to different HAEs. N. pauciflora elicited increased levels of JA and trypsin proteinase inhibitors (TPI) in response to C18:3-Glu and the oral secretions of M. sexta (OS Ms ) but not to oral secretions of S. littoralis (OS Sl ). In contrast, N. miersii only responded to OS Sl but not to the other two HAEs. The specific responses to different HAEs in Nicotiana species are likely due to the perception by the plant of each specific component of the HAE. 2) One HAE can induce different defence responses among closely related Nicotiana species. OS Ms and C18:3-Glu induced JA and TPI accumulations in N. linearis, N. attenuata, N. acuminata and N. pauciflora, but not in N. miersii and N. obtusifolia. 3) The effect of HAE-induced defences differ for the Solanaceae specialist M. sexta and the generalist S. littoralis. Among the four tested Nicotiana species, while the growth rate of M. sexta was only reduced by the induced defences elicited by C18:3-Glu; the growth rate of S. littoralis can be reduced by the induced defences elicited by all three HAEs. This is likely due to differences in the susceptibility of the specialist M. sexta and generalist S. littoralis to induced defences of their host.Closely related Nicotiana species elicit highly specific defence responses to herbivore associated elicitors and provide an ideal framework for investigating the molecular mechanisms and evolutionary divergence of induced resistance in plants.

Dataset Information

Specificity in Mesograzer-Induced Defences in Seagrasses.

Publications

Specificity in Mesograzer-Induced Defences in Seagrasses.

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