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The herbaceous landlord: integrating the effects of symbiont consortia within a single host.

Vandegrift R, Roy BA, Pfeifer-Meister L, Johnson BR, Bridgham SD - PeerJ (2015)

Bottom Line: We hypothesized that the symbionts in our system would be in competition for host resources, that the outcome of that competition could be driven by the benefit to the host, and that the host plants would be able to allocate carbon to the symbionts in such a way as to maximize fitness benefit within a particular environmental context.These results suggest that selective pressure on the host is likely to favor host/symbiont relationships that structure the community of symbionts in the most beneficial way possible for the host, not necessarily favoring the individual symbiont that is most beneficial to the host in isolation.These results highlight the need for a more integrative, systems approach to the study of host/symbiont consortia.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Ecology and Evolution, University of Oregon , Eugene, OR , United States.

ABSTRACT
Plants are typically infected by a consortium of internal fungal associates, including endophytes in their leaves, as well as arbuscular mycorrhizal fungi (AMF) and dark septate endophytes (DSE) in their roots. It is logical that these organisms will interact with each other and the abiotic environment in addition to their host, but there has been little work to date examining the interactions of multiple symbionts within single plant hosts, or how the relationships among symbionts and their host change across environmental conditions. We examined the grass Agrostis capillaris in the context of a climate manipulation experiment in prairies in the Pacific Northwest, USA. Each plant was tested for presence of foliar endophytes in the genus Epichloë, and we measured percent root length colonized (PRLC) by AMF and DSE. We hypothesized that the symbionts in our system would be in competition for host resources, that the outcome of that competition could be driven by the benefit to the host, and that the host plants would be able to allocate carbon to the symbionts in such a way as to maximize fitness benefit within a particular environmental context. We found a correlation between DSE and AMF PRLC across climatic conditions; we also found a fitness cost to increasing DSE colonization, which was negated by presence of Epichloë endophytes. These results suggest that selective pressure on the host is likely to favor host/symbiont relationships that structure the community of symbionts in the most beneficial way possible for the host, not necessarily favoring the individual symbiont that is most beneficial to the host in isolation. These results highlight the need for a more integrative, systems approach to the study of host/symbiont consortia.

No MeSH data available.


Related in: MedlinePlus

Structural equation model results.Overall SEMs, with different models for those plants without Epichloë endophytes (A: E −, blue), and those with Epichloë endophytes (B: E +, red). Model fit was good for both models (A: χ2 = 2.50, P = 0.114; CFI = 0.981; RMSEA = 0.124; n = 99/B: χ2 = 0.63, P = 0.427; CFI = 1.000; RMSEA < 0.001; n = 56). The numbers above the arrows are the standardized path coefficients. Non-significant (P > 0.05) path coefficients are not shown. Numbers in the boxes are total explained variance (R2) of each variable.
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fig-4: Structural equation model results.Overall SEMs, with different models for those plants without Epichloë endophytes (A: E −, blue), and those with Epichloë endophytes (B: E +, red). Model fit was good for both models (A: χ2 = 2.50, P = 0.114; CFI = 0.981; RMSEA = 0.124; n = 99/B: χ2 = 0.63, P = 0.427; CFI = 1.000; RMSEA < 0.001; n = 56). The numbers above the arrows are the standardized path coefficients. Non-significant (P > 0.05) path coefficients are not shown. Numbers in the boxes are total explained variance (R2) of each variable.

Mentions: Infection with Epichloë was 36% (n = 155), and was uncorrelated with any environmental variable (see Figs. S1–S11). We found no evidence of competition between symbionts. Epichloë infection did not affect root length colonized by either AMF (Fig. 3A; F1,153 = 0.956, P = 0.330) or DSE (Fig. 3B; F1,153 = 0.083, P = 0.774). Percent root length colonized by AMF and DSE were correlated positively (Fig. 4 and Fig. S1; Adjusted R2 = 0.107, F1,153 = 19.51, P < 0.001), indicating facilitation rather than competition.


The herbaceous landlord: integrating the effects of symbiont consortia within a single host.

Vandegrift R, Roy BA, Pfeifer-Meister L, Johnson BR, Bridgham SD - PeerJ (2015)

Structural equation model results.Overall SEMs, with different models for those plants without Epichloë endophytes (A: E −, blue), and those with Epichloë endophytes (B: E +, red). Model fit was good for both models (A: χ2 = 2.50, P = 0.114; CFI = 0.981; RMSEA = 0.124; n = 99/B: χ2 = 0.63, P = 0.427; CFI = 1.000; RMSEA < 0.001; n = 56). The numbers above the arrows are the standardized path coefficients. Non-significant (P > 0.05) path coefficients are not shown. Numbers in the boxes are total explained variance (R2) of each variable.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4636405&req=5

fig-4: Structural equation model results.Overall SEMs, with different models for those plants without Epichloë endophytes (A: E −, blue), and those with Epichloë endophytes (B: E +, red). Model fit was good for both models (A: χ2 = 2.50, P = 0.114; CFI = 0.981; RMSEA = 0.124; n = 99/B: χ2 = 0.63, P = 0.427; CFI = 1.000; RMSEA < 0.001; n = 56). The numbers above the arrows are the standardized path coefficients. Non-significant (P > 0.05) path coefficients are not shown. Numbers in the boxes are total explained variance (R2) of each variable.
Mentions: Infection with Epichloë was 36% (n = 155), and was uncorrelated with any environmental variable (see Figs. S1–S11). We found no evidence of competition between symbionts. Epichloë infection did not affect root length colonized by either AMF (Fig. 3A; F1,153 = 0.956, P = 0.330) or DSE (Fig. 3B; F1,153 = 0.083, P = 0.774). Percent root length colonized by AMF and DSE were correlated positively (Fig. 4 and Fig. S1; Adjusted R2 = 0.107, F1,153 = 19.51, P < 0.001), indicating facilitation rather than competition.

Bottom Line: We hypothesized that the symbionts in our system would be in competition for host resources, that the outcome of that competition could be driven by the benefit to the host, and that the host plants would be able to allocate carbon to the symbionts in such a way as to maximize fitness benefit within a particular environmental context.These results suggest that selective pressure on the host is likely to favor host/symbiont relationships that structure the community of symbionts in the most beneficial way possible for the host, not necessarily favoring the individual symbiont that is most beneficial to the host in isolation.These results highlight the need for a more integrative, systems approach to the study of host/symbiont consortia.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Ecology and Evolution, University of Oregon , Eugene, OR , United States.

ABSTRACT
Plants are typically infected by a consortium of internal fungal associates, including endophytes in their leaves, as well as arbuscular mycorrhizal fungi (AMF) and dark septate endophytes (DSE) in their roots. It is logical that these organisms will interact with each other and the abiotic environment in addition to their host, but there has been little work to date examining the interactions of multiple symbionts within single plant hosts, or how the relationships among symbionts and their host change across environmental conditions. We examined the grass Agrostis capillaris in the context of a climate manipulation experiment in prairies in the Pacific Northwest, USA. Each plant was tested for presence of foliar endophytes in the genus Epichloë, and we measured percent root length colonized (PRLC) by AMF and DSE. We hypothesized that the symbionts in our system would be in competition for host resources, that the outcome of that competition could be driven by the benefit to the host, and that the host plants would be able to allocate carbon to the symbionts in such a way as to maximize fitness benefit within a particular environmental context. We found a correlation between DSE and AMF PRLC across climatic conditions; we also found a fitness cost to increasing DSE colonization, which was negated by presence of Epichloë endophytes. These results suggest that selective pressure on the host is likely to favor host/symbiont relationships that structure the community of symbionts in the most beneficial way possible for the host, not necessarily favoring the individual symbiont that is most beneficial to the host in isolation. These results highlight the need for a more integrative, systems approach to the study of host/symbiont consortia.

No MeSH data available.


Related in: MedlinePlus