A fungal endosymbiont affects host plant recruitment through seed‐ and litter‐mediated mechanisms

Omacini, Marina; Chaneton, Enrique J.; Bush, Lowell P.; Ghersa, Claudio M.

doi:10.1111/j.1365-2435.2009.01582.x

Cited by 28 publications

(31 citation statements)

References 55 publications

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“…1). In a microcosm study, Omacini et al (2009) observed that endophyte infection increased L. multiXorum recruitment across a range of microsite conditions created by litter deposition and soil water availability. Laboratory studies also showed enhanced establishment of Lolium arundinaceum (tall fescue) when infected by fungal endophytes (Clay 1987;Rudgers et al 2005).…”

Section: Discussionmentioning

confidence: 97%

“…In greenhouse studies, asexual Neotyphodium endophytes have been found to promote establishment of agronomically important grasses through enhanced seedling emergence and growth (Clay 1987;Rudgers et al 2005;Omacini et al 2009). In contrast, working on a native grass in Weld plots, Faeth and Hamilton (2006) reported lower survival of endophyteinfected relative to uninfected plants during early life stages (seeds and seedlings).…”

Section: Introductionmentioning

confidence: 99%

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Inherited fungal symbionts enhance establishment of an invasive annual grass across successional habitats

2010

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Plants infected with vertically transmitted fungal endophytes carry their microbial symbionts with them during dispersal into new areas. Yet, whether seed-borne endophytes enhance the host plant's ability to overcome colonisation barriers and to regenerate within invaded sites remains poorly understood. We examined how symbiosis with asexual endophytic fungi (Neotyphodium) affected establishment and seed loss to predators in the invasive annual grass Lolium multiflorum (Italian ryegrass) across contrasting successional plots. Italian ryegrass seeds with high and low endophyte incidence were sown into three communities: a 1-year-old fallow field, a 15-year-old grassland, and a 24-year-old forest, which conformed to an old-field chronosequence in the eastern Inland Pampa, Argentina. We found that endophyte infection consistently increased host population recruitment and reproductive output. Endophyte presence also enhanced aerial biomass production of ryegrass in a low recruitment year but not in a high recruitment year, suggesting that symbiotic effects on growth performance are density dependent. Endophyte presence reduced seed removal by rodents, although differential predation may not account for the increased success of infected grass populations. Overall, there was no statistical evidence for an endophyte-by-site interaction, indicating that the fungal endosymbiont benefitted host establishment regardless of large differences in biotic and abiotic environment among communities. Our results imply that hereditary endophytes may increase the chances for host grass species to pass various ecological filters associated with invasion resistance across a broad range of successional habitats.

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Section: Discussionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Inherited fungal symbionts enhance establishment of an invasive annual grass across successional habitats

2010

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“…Altered biomass production or changes in the chemical composition of plant tissues (e.g. concentrations of N, hemicellulose, cellulose, lignin and alkaloids) in response to endophyte presence and interaction with climate change factors may have significant consequences for ecological processes (Omacini et al. , 2009).…”

Section: Introductionmentioning

confidence: 99%

Effects of multiple climate change factors on the tall fescue–fungal endophyte symbiosis: infection frequency and tissue chemistry

et al. 2010

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Summary• Climate change (altered CO 2 , warming, and precipitation) may affect plantmicrobial interactions, such as the Lolium arundinaceum-Neotyphodium coenophialum symbiosis, to alter future ecosystem structure and function.• To assess this possibility, tall fescue tillers were collected from an existing climate manipulation experiment in a constructed old-field community in Tennessee (USA). Endophyte infection frequency (EIF) was determined, and infected (E+) and uninfected (E)) tillers were analysed for tissue chemistry.• The EIF of tall fescue was higher under elevated CO 2 (91% infected) than with ambient CO 2 (81%) but was not affected by warming or precipitation treatments. Within E+ tillers, elevated CO 2 decreased alkaloid concentrations of both ergovaline and loline, by c. 30%; whereas warming increased loline concentrations 28% but had no effect on ergovaline. Independent of endophyte infection, elevated CO 2 reduced concentrations of nitrogen, cellulose, hemicellulose, and lignin.• These results suggest that elevated CO 2 , more than changes in temperature or precipitation, may promote this grass-fungal symbiosis, leading to higher EIF in tall fescue in old-field communities. However, as all three climate factors are likely to change in the future, predicting the symbiotic response and resulting ecological consequences may be difficult and dependent on the specific atmospheric and climatic conditions encountered.

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“…Half of them were treated with triadimenol fungicide (0.5 g p.a./100g seeds) to remove the endophyte (see details in Omacini et al 2004Omacini et al , 2009. 200 seeds) with high (S+: >90%) or low (S-: approx.…”

Section: Experimental Designmentioning

confidence: 99%

“…The interest was mainly triggered because Neotyphodium endophytes, the asexual form of epichloae fungi, synthesize bioactive alkaloids that have shown to be highly effective in deterring herbivores (Clay 1990;Clay & Schardl 2002;Schardl 2010). Alternatively, L. multiflorum is not toxic to livestock when it is naturally symbiotic with N. occultans, although it accumulates loline alkaloids that confer resistance to a wide spectrum of insects (TePaske et al 1993;Moon et al 2000;Omacini et al 2009;Schardl 2010). Alternatively, L. multiflorum is not toxic to livestock when it is naturally symbiotic with N. occultans, although it accumulates loline alkaloids that confer resistance to a wide spectrum of insects (TePaske et al 1993;Moon et al 2000;Omacini et al 2009;Schardl 2010).…”

Section: Introductionmentioning

confidence: 99%

Consequences of grazing on the vertical transmission of a fungal Neotyphodium symbiont in an annual grass population

García-Parisi¹,

Casas

Gundel

et al. 2011

Austral Ecology

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Symbiosis between cool-season grasses and vertically transmitted fungal endophytes are common and significantly impact on ecosystem function. This makes the understanding of the underlying mechanisms to symbiotic individuals frequency in local populations much more interesting. Most studies have been focused on the differential fitness between symbiotic and non-symbiotic counterparts (relative fitness), barely considering other mechanisms. We performed a microcosms experiment to evaluate whether grazing alters the dynamics of the endophyte Neotyphodium occultans in the annual grass Lolium multiflorum by simultaneously modifying the relative fitness and the endophyte efficiency to be transmitted from host plants to seeds. Grazing was simulated by means of clipping and trampling on symbiotic and non-symbiotic plants growing separately, in soils obtained from paddocks, differing in their agronomic management history (natural grassland vs. ryegrass promotion). Seed production showed a complex pattern as it depended on the symbiotic status of the plants, the level of grazing and the agro-ecological context. Grazed plants produced three times fewer seeds than ungrazed plants only in microcosms with endophyte-symbiotic plants in soils from ryegrass promotion. Endophyte benefits on seed production were exclusively observed in ungrazed plants in the same soil. Symbiotic plants produced symbiotic and non-symbiotic seeds in all the treatments. While the production of non-symbiotic seeds by these plants was not affected by grazing and the soil, grazing reduced the production of symbiotic seeds in both contexts. Grazing negative effect on the density of fully infected spikes determined a significant increment in the transmission failures which were not modified by agro-ecological contexts.Therefore, grazing can modulate symbiosis dynamics through reducing seed production and endophyte transmission efficiency. Transmission has been disregarded, but it is a context-dependent process that could lead to a gradual reduction in the symbiotic plants frequency in a population if the mutualism effectiveness does not outweigh transmission failures.

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A fungal endosymbiont affects host plant recruitment through seed‐ and litter‐mediated mechanisms

Cited by 28 publications

References 55 publications

Inherited fungal symbionts enhance establishment of an invasive annual grass across successional habitats

Inherited fungal symbionts enhance establishment of an invasive annual grass across successional habitats

Effects of multiple climate change factors on the tall fescue–fungal endophyte symbiosis: infection frequency and tissue chemistry

Consequences of grazing on the vertical transmission of a fungal Neotyphodium symbiont in an annual grass population

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