An arbuscular mycorrhizal fungus accelerates decomposition and acquires nitrogen directly from organic material

Hodge, Angela; Campbell, Colin D.; Fitter, A. H.

doi:10.1038/35095041

Cited by 921 publications

(619 citation statements)

References 25 publications

(20 reference statements)

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“…We formulate the additional hypothesis that the symbiosis of ericaceous plants with their ericoid mycorrhizal fungi that degrade protein-phenolic complexes in the soil enables them to use organic nitrogen sources not available to other plants like grasses with their arbuscular mycorrhizal fungi (Berendse and Elberse 1990;Northup et al 1995;Hättenschwiler and Vitousek 2000;Hodge et al 2001;Aerts 2002).…”

Section: Responses Of Tannins To N Supply and Light Intensitymentioning

confidence: 99%

The effect of nutrient supply and light intensity on tannins and mycorrhizal colonisation in Dutch heathland ecosystems

Hofland-Zijlstra

Berendse

2008

Plant Ecol

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(1) Increased atmospheric nitrogen deposition has shifted plant dominance from ericaceous plants to grass species. To elucidate the reduced competitiveness of heather, we tested the hypothesis that additions of nitrogen reduce the concentrations of phenolics and condensed tannins in ericaceous leaves and retard mycorrhizal colonisation in ericaceous plants. We also tested the negative effects of reduced light intensity on carbon-based secondary compounds and mycorrhizal colonisation in ericaceous plants. (2) We performed a field inventory at three heathland sites in the Netherlands varying in nutrient supply and light intensity. Leaves of ericaceous plants and grasses were collected and analysed for concentrations of tannins, phenolics and nutrients. Similarly, we took root samples to record mycorrhizal colonisation and soil samples to measure the soil mineralisation. In addition, we conducted two-factorial experiments with Calluna vulgaris plants, in which we varied fertiliser and shade levels under greenhouse and field conditions. (3) The field inventory revealed that nitrogen addition and shading both negatively affected the concentration of total phenolics. The total phenolics and condensed tannin concentrations were positively correlated (P \ 0.001), but in the field experiment, the condensed tannins were not significantly affected by the treatments. Our results provide the first evidence that the carbon nutrient balance can be used to predict the amount of total phenolics in the dwarf shrub C. vulgaris. (4) In the field experiments, shading of plants resulted in significantly less mycorrhizal colonisation. Only in the greenhouse experiment did addition of nitrogen negatively affect mycorrhizal colonisation. (5) Our results imply that increased atmospheric nitrogen deposition can depress the tannin concentrations in ericaceous plants and the mycorrhizal colonisation in roots, thereby reducing the plants' competitiveness with respect to grasses. Additionally, if ericaceous plants are shaded by grasses that have become dominant due to increased nitrogen supply, these effects will be intensified and competitive replacement will be accelerated.

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Section: Responses Of Tannins To N Supply and Light Intensitymentioning

confidence: 99%

The effect of nutrient supply and light intensity on tannins and mycorrhizal colonisation in Dutch heathland ecosystems

Hofland-Zijlstra

Berendse

2008

Plant Ecol

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“…This hypothesis is supported by transcriptional data: transcripts encoding enzymes that assimilate inorganic N have been detected in the extraradical mycelium, whereas those involved in Arg breakdown are expressed in the intraradical fungal structures (Govindarajulu et al, 2005;LopezPedrosa et al, 2006). Furthermore, evidence is now accruing that AM fungi may have access to organic N sources (Hodge et al, 2001;Leigh et al, 2009) thanks to the expression of specific amino acid permeases (Cappellazzo et al, 2008). The way in which N is transferred from the AM fungi to their host is still under debate.…”

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A Mycorrhizal-Specific Ammonium Transporter from Lotus japonicus Acquires Nitrogen Released by Arbuscular Mycorrhizal Fungi

et al. 2009

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In mycorrhizal associations, the fungal partner assists its plant host by providing nitrogen (N) in addition to phosphate. Arbuscular mycorrhizal (AM) fungi have access to inorganic or organic forms of N and translocate them via arginine from the extra-to the intraradical mycelium, where the N is transferred to the plant without any carbon skeleton. However, the molecular form in which N is transferred, as well as the involved mechanisms, is still under debate. NH 4 + seems to be the preferential transferred molecule, but no plant ammonium transporter (AMT) has been identified so far. Here, we offer evidence of a plant AMT that is involved in N uptake during mycorrhiza symbiosis. The gene LjAMT2;2, which has been shown to be the highest up-regulated gene in a transcriptomic analysis of Lotus japonicus roots upon colonization with Gigaspora margarita, has been characterized as a high-affinity AMT belonging to the AMT2 subfamily. It is exclusively expressed in the mycorrhizal roots, but not in the nodules, and transcripts have preferentially been located in the arbusculated cells. Yeast (Saccharomyces cerevisiae) mutant complementation has confirmed its functionality and revealed its dependency on acidic pH. The transport experiments using Xenopus laevis oocytes indicated that, unlike other plant AMTs, LjAMT2;2 transports NH 3 instead of NH 4 + . Our results suggest that the transporter binds charged ammonium in the apoplastic interfacial compartment and releases the uncharged NH 3 into the plant cytoplasm. The implications of such a finding are discussed in the context of AM functioning and plant phosphorus uptake.

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“…Grass species, on the other hand, predominantly colonized by arbuscular mycorrhizal fungi, are often assumed to be less able to utilize organic soil nitrogen. Although it has been shown that arbuscular mycorrhizal fungi can enhance amino acid absorption in plants, this seemed to occur only to a small extent (Hodge 2001;Hodge et al 2001). Separate from this, there is evidence that grasses can absorb simple forms of organic nitrogen such as amino acids like glycine or methylamine (Näsholm et al 1998;FalkengrenGrerup et al 2000).…”

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confidence: 99%

Effects of litters with different concentrations of phenolics on the competition between Calluna vulgaris and Deschampsia flexuosa

Hofland-Zijlstra

Berendse

2009

Plant Soil

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We hypothesized that the outcome of competition between ericaceous plants and grasses is strongly affected by the concentrations of phenolics in the litter that they produce. To test the effect of phenolic-rich litter on soluble soil nitrogen concentrations, plant nitrogen uptake and inter-specific competition, we conducted a greenhouse experiment with the shrub Calluna vulgaris and the grass Deschampsia flexuosa and their leaf litters. Two litters of C. vulgaris were used, with equal nitrogen concentration but different (high and low) concentrations of total phenolics. The D. flexuosa leaf litter contained lower concentrations of phenolics, but higher concentrations of nitrogen than the C. vulgaris litters. The plants were grown in monocultures and in mixed cultures. Inorganic and dissolved organic nitrogen were measured monthly during the experiment. After four months, we measured above-and belowground biomass and the nutrient concentrations in above-and belowground plant parts. In monocultures, C. vulgaris produced more shoot and root biomass on its own litter than with no litter. Growth of Calluna was reduced on grass litter. D. flexuosa plants produced most biomass on their own litter type, whether in monocultures or in mixed cultures. Addition of Calluna litter stimulated the growth of D. flexuosa both in monoculture and in mixtures. The grass plants outcompeted Calluna both on shrub litter and on grass litter but not when grown without litter. The two C. vulgaris litter types that differed in their concentration of phenolics did not differ in their effects on the competition between the two species or on the production of inorganic and dissolved organic nitrogen. We conclude that the nitrogen content of the litter is more important as a plant feature driving competition between shrubs and grasses than the concentrations of phenolics.

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An arbuscular mycorrhizal fungus accelerates decomposition and acquires nitrogen directly from organic material

Cited by 921 publications

References 25 publications

The effect of nutrient supply and light intensity on tannins and mycorrhizal colonisation in Dutch heathland ecosystems

The effect of nutrient supply and light intensity on tannins and mycorrhizal colonisation in Dutch heathland ecosystems

A Mycorrhizal-Specific Ammonium Transporter from Lotus japonicus Acquires Nitrogen Released by Arbuscular Mycorrhizal Fungi

Effects of litters with different concentrations of phenolics on the competition between Calluna vulgaris and Deschampsia flexuosa

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