Most cited article - PubMed ID 29681914
Little Cross-Feeding of the Mycorrhizal Networks Shared Between C3-Panicum bisulcatum and C4-Panicum maximum Under Different Temperature Regimes
Plant-plant interactions and coexistence can be directly mediated by symbiotic arbuscular mycorrhizal (AM) fungi through asymmetric resource exchange between the plant and fungal partners. However, little is known about the effects of AM fungal presence on resource allocation in mixed plant stands. Here, we examined how phosphorus (P), nitrogen (N) and carbon (C) resources were distributed between coexisting con- and heterospecific plant individuals in the presence or absence of AM fungus, using radio- and stable isotopes. Congeneric plant species, Panicum bisulcatum and P. maximum, inoculated or not with Rhizophagus irregularis, were grown in two different culture systems, mono- and mixed-species stands. Pots were subjected to different shading regimes to manipulate C sink-source strengths. In monocultures, P. maximum gained more mycorrhizal phosphorus uptake benefits than P.bisulcatum. However, in the mixed culture, the AM fungus appeared to preferentially transfer nutrients (33P and 15N) to P.bisulcatum compared to P. maximum. Further, we observed higher 13C allocation to mycorrhiza by P.bisulcatum in mixed- compared to the mono-systems, which likely contributed to improved competitiveness in the mixed cultures of P.bisulcatum vs. P. maximum regardless of the shading regime. Our results suggest that the presence of mycorrhiza influenced competitiveness of the two Panicum species in mixed stands in favor of those with high quality partner, P. bisulcatum, which provided more C to the mycorrhizal networks. However, in mono-species systems where the AM fungus had no partner choice, even the lower quality partner (i.e., P.maximum) could also have benefitted from the symbiosis. Future research should separate the various contributors (roots vs. common mycorrhizal network) and mechanisms of resource exchange in such a multifaceted interaction.
Arbuscular mycorrhizal (AM) fungi can support the establishment of mycotrophic plants in new environments. However, the role of mycorrhizal symbiosis in interactions between perennial and weedy annual plants is not well understood. In our current study, we examine how widespread generalist AM fungi and soil disturbance, including disturbance of AM fungal networks (CMNs), affect the performance of two late-successional perennial plants of Central Europe, Senecio jacobaea and Crepis biennis, co-occurring with weedy annual forbs, Conyza canadensis and Erigeron annuus. Although presence of weedy annual E. annuus or C. canadensis did not affect the performance of the paired perennials, AM fungi supported perennial C. biennis in competition with weedy annual E. annuus. However, this AM-aided underpinning was independent of disturbance of CMNs. Conversely, although AM fungi benefited perennial S. jacobaea, this did not affect its competitive abilities when grown with weedy annual C. canadensis. Similarly, soil disturbance, independent of AM fungal presence, improved plant tissue P and biomass production of S. jacobaea, but not its competitive abilities. Our results show AM fungi may be advantageous for perennial plants growing in competition with weedy annual plants. Therefore, maintaining healthy soils containing an abundance of AM fungi, may encourage late successional perennial plants, potentially limiting establishment of weedy annual plant species.
- MeSH
- Marijuana Abuse * MeSH
- Mycorrhizae * MeSH
- Skin Neoplasms MeSH
- Nevus, Pigmented MeSH
- Plant Weeds MeSH
- Soil MeSH
- Senecio * MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Names of Substances
- Soil MeSH
- Keywords
- beneficial microbes, human needs, nutrient limitation, pathogens, plant stress, soil health, sustainability, sustainable agro-ecosystem,
- Publication type
- Editorial MeSH
Symbiosis between plants and arbuscular mycorrhizal (AM) fungi, involving great majority of extant plant species including most crops, is heavily implicated in plant mineral nutrition, abiotic and biotic stress tolerance, soil aggregate stabilization, as well as shaping soil microbiomes. The latter is particularly important for efficient recycling from soil to plants of nutrients such as phosphorus and nitrogen (N) bound in organic forms. Chitin is one of the most widespread polysaccharides on Earth, and contains substantial amounts of N (>6% by weight). Chitin is present in insect exoskeletons and cell walls of many fungi, and can be degraded by many prokaryotic as well as eukaryotic microbes normally present in soil. However, the AM fungi seem not to have the ability to directly access N bound in chitin molecules, thus relying on microbes in their hyphosphere to gain access to this nutrient-rich resource in the process referred to as organic N mineralization. Here we show, using data from two pot experiments, both including root-free compartments amended with 15N-labeled chitin, that AM fungi can channel substantial proportions (more than 20%) of N supplied as chitin into their plants hosts within as short as 5 weeks. Further, we show that overall N losses (leaching and/or volatilization), sometimes exceeding 50% of the N supplied to the soil as chitin within several weeks, were significantly lower in mycorrhizal as compared to non-mycorrhizal pots. Surprisingly, the rate of chitin mineralization and its N utilization by the AM fungi was at least as fast as that of green manure (clover biomass), based on direct 15N labeling and tracing. This efficient N recycling from soil to plant, observed in mycorrhizal pots, was not strongly affected by the composition of AM fungal communities or environmental context (glasshouse or outdoors, additional mineral N supply to the plants or not). These results indicate that AM fungi in general can be regarded as a critical and robust soil resource with respect to complex soil processes such as organic N mineralization and recycling. More specific research is warranted into the exact molecular mechanisms and microbial players behind the observed patterns.
In a globalized world, plant invasions are common challenges for native ecosystems. Although a considerable number of invasive plants form arbuscular mycorrhizae, interactions between arbuscular mycorrhizal (AM) fungi and invasive and native plants are not well understood. In this study, we conducted a greenhouse experiment examining how AM fungi affect interactions of co-occurring plant species in the family Asteracea, invasive Echinops sphaerocephalus and native forb of central Europe Inula conyzae. The effects of initial soil disturbance, including the effect of intact or disturbed arbuscular mycorrhizal networks (CMNs), were examined. AM fungi supported the success of invasive E. sphaerocephalus in competition with native I. conyzae, regardless of the initial disturbance of CMNs. The presence of invasive E. sphaerocephalus decreased mycorrhizal colonization in I. conyzae, with a concomitant loss in mycorrhizal benefits. Our results confirm AM fungi represent one important mechanism of plant invasion for E. sphaerocephalus in semi-natural European grasslands.
- MeSH
- Echinops Plant microbiology physiology MeSH
- Glomeromycota physiology MeSH
- Inula microbiology physiology MeSH
- Mycorrhizae physiology MeSH
- Grassland MeSH
- Soil Microbiology MeSH
- Introduced Species * MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Geographicals
- Europe MeSH
The relationship between mycorrhiza functioning and composition of arbuscular mycorrhizal (AM) fungal communities is an important but experimentally still rather little explored topic. The main aim of this study was thus to link magnitude of plant benefits from AM symbiosis in different abiotic contexts with quantitative changes in AM fungal community composition. A synthetic AM fungal community inoculated to the model host plant Medicago truncatula was exposed to four different abiotic contexts, namely drought, elevated phosphorus availability, and shading, as compared to standard cultivation conditions, for two cultivation cycles. Growth and phosphorus uptake of the host plants was evaluated along with the quantitative composition of the synthetic AM fungal community. Abiotic context consistently influenced mycorrhiza functioning in terms of plant benefits, and the effects were clearly linked to the P requirement of non-inoculated control plants. In contrast, the abiotic context only had a small and transient effect on the quantitative AM fungal community composition. Our findings suggest no relationship between the degree of mutualism in AM symbiosis and the relative abundances of AM fungal species in communities in our simplified model system. The observed progressive dominance of one AM fungal species indicates an important role of different growth rates of AM fungal species for the establishment of AM fungal communities in simplified systems such as agroecosystems.
- Keywords
- Community, Medicago truncatula, Mycorrhizal functioning, Phosphorus, Pre-conditioning, qPCR,
- MeSH
- Phosphorus analysis MeSH
- Medicago truncatula microbiology MeSH
- Mycobiome * MeSH
- Mycorrhizae physiology MeSH
- Droughts MeSH
- Sunlight MeSH
- Symbiosis * MeSH
- Publication type
- Journal Article MeSH
- Names of Substances
- Phosphorus MeSH
Biochar has been heralded as a multipurpose soil amendment to sustainably increase soil fertility and crop yields, affect soil hydraulic properties, reduce nutrient losses, and sequester carbon. Some of the most spectacular results of biochar (and organic nutrient) inputs are the terra preta soils in the Amazon, dark anthropogenic soils with extremely high fertility sustained over centuries. Such soil improvements have been particularly difficult to achieve on a short run, leading to speculations that biochar may need to age (weather) in soil to show its best. Further, interaction of biochar with arbuscular mycorrhizal fungi (AMF), important root symbionts of a great majority of terrestrial plants including most agricultural crops, remains little explored. To study the effect of aged biochar on highly mycotrophic Andropogon gerardii plants and their associated AMF, we made use of softwood biochar, collected from a historic charcoal burning site. This biochar (either untreated or chemically activated, the latter serving as a proxy for freshly prepared biochar) was added into two agricultural soils (acid or alkaline), and compared to soils without biochar. These treatments were further crossed with inoculation with a synthetic AMF community to address possible interactions between biochar and the AMF. Biochar application was generally detrimental for growth and mineral nutrition of our experimental plants, but had no effect on the extent of their root colonized by the AMF, nor did it affect composition of their root-borne AMF communities. In contrast, biochar affected development of two out of five AMF (Claroideoglomus and Funneliformis) in the soil. Establishment of symbiosis with AMF largely mitigated biochar-induced suppression of plant growth and mineral nutrition, mainly by improving plant acquisition of phosphorus. Both mycorrhizal and non-mycorrhizal plants grew well in the acid soil without biochar application, whereas non-mycorrhizal plants remained stunted in the alkaline soils under all situations (with or without biochar). These different and strong effects indicate that response of plants to biochar application are largely dependent on soil matrix and also on microbes such as AMF, and call for further research to enable qualified predictions of the effects of different biochar applications on field-grown crops and soil processes.
- Keywords
- arbuscular mycorrhizal fungi, community, historic biochar, mycorrhizal response, nitrogen, phosphorus,
- Publication type
- Journal Article MeSH
