A Numerical Analysis of Published Field Trials with Vesicular-Arbuscular Mycorrhizal Fungi

McGonigle, Terence P.

doi:10.2307/2389390

Cited by 110 publications

(58 citation statements)

References 29 publications

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“…Still, we might not have reached the threshold of P (concurrent with carbon limitation) to induce parasitism. Alternatively, although root colonization is not consistently linked with growth benefits (McGonigle 1988), it is possible that the limited benefit plants derived from AMF in high-P treatments is due, at least in part, to lower colonization rates. A decline in AMF colonization may be expected if, in the presence of additional P, plants allocate photosynthate to growth and AMF become C limited.…”

Section: Discussionmentioning

confidence: 99%

Community‐level consequences of mycorrhizae depend on phosphorus availability

Collins

Foster

2009

Ecology

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Abstract. In grasslands, arbuscular mycorrhizal fungi (AMF) mediate plant diversity; whether AMF increase or decrease diversity depends on the relative mycotrophy in dominant vs. subordinate plants. In this study we investigated whether soil nutrient levels also influence the ability of AMF to mediate plant species coexistence. First, we developed a conceptual model that predicts the influence of AMF on diversity along a soil nutrient gradient for plant communities dominated by mycotrophic and non-mycotrophic species. To test these predictions, we manipulated phosphorus to create a soil nutrient gradient for mesocosm communities composed of native prairie grasses and then compared community properties for mesocosms with and without AMF. We found that, where P was limiting, AMF increased plant diversity and productivity, and also altered community structure; however, at high P, AMF had little influence on aboveground communities. Compositional differences among treatments were due largely to a trade-off in the relative abundance of C 3 vs. C 4 species. Our study emphasizes how environmental constraints on mutualisms may govern community-and ecosystem-level properties.

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Section: Discussionmentioning

confidence: 99%

Community‐level consequences of mycorrhizae depend on phosphorus availability

Collins

Foster

2009

Ecology

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“…Synchronised development has been confirmed by detailed morphological studies, which also demonstrated the short lifespan of the active interface (Hartig nets, arbuscules, or coils). The link between mycorrhizal development and plant benefit is supported by experimental studies where valid comparisons were made (Table 1), but this relationship is often obscured by other factors in field trials (McGonigle, 1988).…”

Section: Synchronised Developmentmentioning

confidence: 99%

Diversity and classification of mycorrhizal associations

2004

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Most mycorrhizas are ' balanced ' mutualistic associations in which the fungus and plant exchange commodities required for their growth and survival. Myco-heterotrophic plants have 'exploitative ' mycorrhizas where transfer processes apparently benefit only plants. Exploitative associations are symbiotic (in the broad sense), but are not mutualistic. A new definition of mycorrhizas that encompasses all types of these associations while excluding other plant-fungus interactions is provided. This definition recognises the importance of nutrient transfer at an interface resulting from synchronised plant-fungus development. The diversity of interactions between mycorrhizal fungi and plants is considered. Mycorrhizal fungi also function as endophytes, necrotrophs and antagonists of host or non-host plants, with roles that vary during the lifespan of their associations. It is recommended that mycorrhizal associations are defined and classified primarily by anatomical criteria regulated by the host plant. A revised classification scheme for types and categories of mycorrhizal associations defined by these criteria is proposed. The main categories of vesicular-arbuscular mycorrhizal associations (VAM) are 'linear' or 'coiling ', and of ectomycorrhizal associations (ECM) are ' epidermal ' or 'cortical '. Subcategories of coiling VAM and epidermal ECM occur in certain host plants. Fungus-controlled features result in ' morphotypes ' within categories of VAM and ECM. Arbutoid and monotropoid associations should be considered subcategories of epidermal ECM and ectendomycorrhizas should be relegated to an ECM morphotype. Both arbuscules and vesicles define mycorrhizas formed by glomeromycotan fungi. A new classification scheme for categories, subcategories and morphotypes of mycorrhizal associations is provided.

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“…This strong dependency of mycorrhizal effects on plant density might explain why results of field studies on the effects of mycorrhizal infection on P uptake by plants have been conflicting (Fitter, 1985) and have rarely shown the expected increase in biomass due to the symbiosis (McGonigle, 1988).…”

Section: mentioning

confidence: 99%

Interactive effects of arbuscular mycorrhizal symbiosis, intraspecific competition and resource availability on Trifolium subterraneum cv. Mt. Barker

Facelli

Smith

et al. 1999

New Phytologist

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We performed two glasshouse experiments to determine whether the presence of arbuscular mycorrhizal symbiosis reduces the intensity of intraspecific competition at low concentrations of available phosphorus (P), and whether this effect is modified by a reduction in light intensity. In the first experiment, Trifolium subterraneum cv. Mt. Barker was grown at different densities in controlled conditions of light and temperature, and half of the pots were inoculated with spores of the arbuscular mycorrhizal fungus, Gigaspora margarita. In the second experiment, the plants were grown in similar controlled conditions but the light intensity received by half of the pots was reduced by 50%. The biomass and P content of individual mycorrhizal plants and the biomass response to mycorrhizal infection were drastically reduced as plant density increased. The effects of density on percentage infection, shoot and root P concentrations, and root : shoot ratios were inconsistent. Generally reduction in light intensity did not alter these effects. Mycorrhizal symbiosis increased intraspecific competition intensity through an increase in the availability of soil P. This increase in competition was reflected in the greater size inequality of low density mycorrhizal treatments. Our results emphasize that the main effects of mycorrhizas at the individual level cannot be expected to be apparent at the population level, because they are overridden by density-dependent processes.

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A Numerical Analysis of Published Field Trials with Vesicular-Arbuscular Mycorrhizal Fungi

Cited by 110 publications

References 29 publications

Community‐level consequences of mycorrhizae depend on phosphorus availability

Community‐level consequences of mycorrhizae depend on phosphorus availability

Diversity and classification of mycorrhizal associations

Interactive effects of arbuscular mycorrhizal symbiosis, intraspecific competition and resource availability on Trifolium subterraneum cv. Mt. Barker

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