This research highlights the water-conserving properties mycorrhizal colonisation may convey upon a host plant. Achatz et al.
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Together these studies elegantly demonstrate how below-ground interactions play a key role in regulating plant community structure and composition. Other plant-insect interactions are also affected by associations with mycorrhizal fungi, and Kempel et al. Non-mycorrhizal fungi respond negatively to colonisation of host plants by mycorrhizas, as demonstrated by Liu et al. Reduced concentrations of the foliar endophyte Neotyphodium were shown in two ryegrass cultivars when colonised by mycorrhizal fungi of the Glomeromycota, and vice versa.
This suggests such interactions are complex and the benefits of both endosymbionts must be balanced with environmental constraints. Schausberger et al. These compounds are attractive to predatory spider mites that prey upon herbivore pests, providing a mechanism for inter-trophic level signalling as part of plant defence systems. Babikova et al investigated the effect of mycorrhizal colonisation on the production of other plant VOCs and their attractiveness to sap-sucking aphids.
They found that colonisation by mycorrhizal fungi actually increased the attractiveness of plants to aphids through enhanced nutrition leading to production of more attractive VOCs, although this was dependent on timing of initiation of fungal colonisation. In all treatments aphid infestation led to reduction in mycorrhizal colonisation of host plants, creating a potential feedback loop. Further research of multi-trophic levels by Kempel et al.
This suggests that while fungi-plant-herbivore interactions are diverse in nature, there is scope for mycorrhizas having far-reaching impacts on surrounding communities of plants, insects and micro-organisms, even in recently introduced species. Together, this collection of research demonstrate how below-ground microbial processes can heavily influence above-ground interactions, a mechanism influencing community structure and function that is all too often overlooked.
The roles of mycorrhizal fungi in regulating community and wider ecosystem structure, both directly and indirectly, and the mechanisms by which it may occur have major implications for their use within sustainable agriculture. Since the post-war Green Revolution, agricultural productivity has increased dramatically in terms of crop yield and predictability, dependent largely on the development and application of novel pesticides and nitrogen- and phosphorus-based fertilisers, coupled to advances in plant breeding and genetic technologies.
However, in the last 15 years key crop yields have plateaued and we must now look to more sustainable agricultural solutions to secure global food supplies in a more environmentally sustainable fashion. Application of mycorrhizal inoculum to crop plants may help reduce use of chemical fertilisers by providing alternative routes for enhancing crop nutrition, however much of the research surrounding this is concentrated on short-term experimental evidence. Antunes et al. Their findings demonstrate significant flexibility in mycorrhizal functioning and emphasise the importance of considering long-term site history in using such inocula.
The research highlighted in this Virtual Issue of Functional Ecology illustrates that mycorrhiza-plant-community interactions are a critically important and dynamic component of ecosystem structure and function. These often multi-trophic interactions have, until relatively recently, been largely overlooked by ecologists seeking to understand why and how plant communities are structured, and the implications of this within the wider context of future climate change and the global need for improved land remediation and improved and sustainable agricultural practices.
As such, critical knowledge-gaps still exist in this area. Future research should also focus on improving our understanding of the processes by which mycorrhizas access and distribute soil resources, how this is affected by pollutants and atmospheric CO2 and the resulting impacts on community composition and function in natural and agricultural systems.
Arbuscular mycorrhizal fungi and aphids interact by changing host plant quality and volatile emission Babikova Z. Carbon transfer between plants and its control in networks of arbuscular mycorrhizas Fitter A. Trait-mediated effect of arbuscular mycorrhiza on the competitive effect and response of a monopolistic species Gross N. Microbial mediation of plant competition and community structure Hodge A. Endophyte symbiosis benefits a rare grass under low water availability Kannadan S. Support from the underground: induced plant resistance depends on arbuscular mycorrhizal fungi Kempel A.
Competition between foliar Neotyphodium lolii endophytes and mycorrhizal Glomus spp. Mycorrhiza changes plant volatiles to attract spider mite enemies Schausberger P. Decomposers in disguise: mycorrhizal fungi as regulators of soil C dynamics in ecosystems under global change Talbot J. Gender dimorphism and mycorrhizal symbiosis affect floral visitors and reproductive output in Geranium sylvaticum Varga S.
Phosphorus uptake, not carbon transfer, explains arbuscular mycorrhizal enhancement of Centaurea maculosa in the presence of native grassland species Zabinski C. Achatz M. Functional Ecology.
Antunes P. Arbuscular mycorrhizal symbiosis, ecosystem processes and environmental changes in tropical soils. T1 - Arbuscular mycorrhizal symbiosis, ecosystem processes and environmental changes in tropical soils. N2 - Arbuscular mycorrhizal fungi AMF are more widely distributed and associate with a wide range of plant species. AB - Arbuscular mycorrhizal fungi AMF are more widely distributed and associate with a wide range of plant species. Arbuscular mycorrhizal symbiosis, ecosystem processes and environmental changes in tropical soils Geofrey Soka, Mark E Ritchie.
Department of Biology. Abstract Arbuscular mycorrhizal fungi AMF are more widely distributed and associate with a wide range of plant species. Fingerprint tropical soil. Applied Ecology and Environmental Research , 13 1 , Soka G , Ritchie ME. Soil pH is a critical factor in studying endomycorrhizal fungi ecology. For example, low soil pH has effect on the uptake and movement of phosphorus in rhizosphere and plant nutrient supply mechanisms Giri et al. Gigaspora sp.
Other strains also could improve plant growth and enhance plant tolerance to acidity. The report was indicated that VA mycorrhizal fungi differed in the tolerance to soil acidity and so did their inoculation effects. Crop rotation is a very ancient cultural practice Howard, Crop rotation has critical effect on soil microbial communities, soil structure and organic mater Curl, The main idea behind crop rotation practice is to disrupt disease cycle Pierce and Rice, Few research has been executed to distinguished mycorrhizal fungi community composition and diversity.
The AMF spores surveys as a baseline in the field soil to assess the impact of agricultural practices on mycorrhizosphere Douds and Millner, Some researchers showed that introduction of leguminous plant for a season into conventional system of maize increased microbial diversity Bunemann et al. Agricultural practices management influence AMF communities structure quantitatively and qualitatively Miller et al.
Crop rotation is known to affect AMF in the field. Crop rotation also affects species diversity Douds et al. Crop rotation affected spore population of AMF in another crop-rotation management trial utilizing a maize-vegetable-small grain rotation and chemical fertilizer or organic amendments as sources of mineral nutrients Douds et al. One of the most important mechanisms to understand the effect of VAM on plant root system is the nutrition supply Davamani et al. The additional of fertilizer and organic matter improved soil properties such as fertility, water-holding capacity, aggregation, bulk density, hydraulic conductivity the degree of compaction and resistance to water Franzluebbers, Mycorrhizas fungal hyphae play great role by binding agents within and between aggregates Ortas and Lal, In the mycorrhizosphere, mycorrhizal hyphae may contribute further to the aggregating effect as they grow into small pores and bind soil particles together Miller and Jastrow, Bearden and Petersen reported that mycorrhiza played a significant role in the formation of aggregates and aggregate stability.
Mycorrhizal polysaccharide shown to bound the soil particles Tisdall, Water-stable soil aggregates were correlated positively with root and arbuscular mycorrhizae soil mycelium development Celik et al. Mycorrhiza have also benefited for the soil rehabilitation, soil ecology and erosion control by stimulating soil Ortas and Lal, Eight years of fertilization of low nutrient soil caused population of Gigaspora gigantea to decline and Glomus intraradices to increase Johnson and Pfleger, Phosphorus is generally considered to be the most important plant-growth factor which can be supplied by mycorrhizal association, because of many biotic and abiotic factors that restrict its mobility in soil Smith and Read, Phosphorus fertilizers are known to inhibit colonization of roots and spore production by AMF Douds and Schenk, In agricultural soils, a decline in numbers of viable and healthy AM propagules can occur during long weed-free fallows or during rotation with non-mycotrophic plants Johnson and Pfleger, Drought stress results in greater yield loss than any other single biotic or abiotic factor Ober, ; Boyer, Wheat Triticum durum Desf.
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The Glomus mosseae and G. Michelsen and Rosendahl reported that the drought treatment reduced Acacia nilotica and Leucaena leucocephala seedlings biomass and nodulation. Several interactions between mycorrhizal fungi, their hosts and the environment must be recognized in considering the impact of pesticides Tu, Cause and effect can be difficult to determine, because what influences the fungus may thereby indirectly influence the host and vice versa Schuepp and Bodmer, An herbicide that severely damages the host will almost certainly damage the mycorrhizae and conse-pesticide effects on soil microbes have been tested mostly in agricultural soils Atlas et al.
Colinas pesticides have been widely used in forests and forest nurseries against fungal diseases fungicides , weeds herbicides and herbivores insecticides. Mycorrhizal fungi grow with the roots of many plants and aid in nutrient uptake. These fungi can also be damaged by herbicides in the soil. One study found that oryzalin and trifluralin both inhibited the growth of certain species of mycorrhizal fungi Kelley and South, Roundup has been shown to be toxic to mycorrhizal fungi in laboratory studies and some damaging effects were seen at concentrations lower than those found in soil following typical applications Estok et al.
Triclopyr was also found to be toxic to several species of mycorrhizal fungi and oxadiazon reduced the number of mycorrhizal fungal spores. Pesticide residues are found in soil and air and in surface and ground water across the nation and urban pesticide uses contribute to the problem Chakravarty et al. Pesticide contamination poses significant risks to the environment and non-target organisms ranging from beneficial soil microorganisms, insects, plants, fish and birds. Contrary to common misconceptions, even herbicides can cause harm to the environment.
In fact, weed killers can be especially problematic because they are used in relatively large volumes Moorman, The best way to reduce pesticide contamination and the harm it causes in our environment is for all of us to do our part to use safer, non-chemical pest control including weed control methods MC, Many soils around the world are polluted with heavy metals and are therefore, of limited value for farming purposes Hildebrandt et al.
AMF could be of particular benefit to plants in relation to alleviating heavy metal Leyval et al. Plants growing in heavy metal soils can be colonized by AMF. Recent reviews on this subject are available Jeffries et al. The work of Hildebrandt et al. It has often been stressed that specific AMF spores from heavy metal soils possess enormous potential for phytoremediation. Khan reported the potential use of AMF in detoxification of heavy metals in environments polluted.
It is suggested that AMF are mycobionts that could be exploited in such processes. The research results reported by Val et al. Several studies investigating the role of AMF in protection against salt stress Wang et al. Salinization is a serious soil problem and it is increasing steadily in several parts of the world, in particular in semiarid and arid areas Giri et al.
AMF have been known to occur naturally in saline environments Harinasut et al. The average density of spores in saline areas is reported to be low by some researchers Barrow et al. Aliasgharzadeh et al. The higher fungal spore production in saline soils may be due to the sporulation is stimulated under salt stress which means that AMF may produce spores at low root-colonization levels in severe saline conditions.
This is in contrast to other researchers on saline soils where low or even zero spore population was found in soils with ECe approx. Salinity, not only affects the host but also the AMF. It can hamper colonization percentage, growth of hyphae and spore germination of the fungus. Numerous researchers have documented the negative effects of salinity on the fungus McMillen et al.
Some researchers have reported that the symbiosis results in increased minerals uptake Tahat et al. Daei et al. The symbiosis of Glomus etunicatum and G.
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The authors would like to thank University Putra Malaysia for supporting this work. Abbott, L.
Robson, The effect of soil pH on the formation of VA mycorrhizas by two species of Glomus. Soil Res. Clark, Water stress and mycorrhizal isolate effect on growth and nutrient acquisition of wheat. Plant Nutr. Nursery inoculation of tomato with arbuscular mycorrhizal fungi and subsequent performance under irrigation with saline water. Rastin, H. Towfighi and A. Alizadeh, Occurrence of arbuscular mycorrhizal fungi in saline soils of the Tabriz Plain of Iran in relation to some physical and chemical properties of soil.
Mycorrhiza, Pramer and R. Bartha, Assessment of pesticides on non-target soil microorganisms. Soil Biol. Havstad and B. McCaslin, Fungal root endophytes in four wing saltbrush, Atriplex canescens, on arid rangeland of southwestern USA. Arid Soil Res. Petersen, Influence of arbuscular mycorrhizal fungi on soil structure and aggregate stability of a vertisol. Plant Soil, Selvaraj, Seasonal incidence and distribution of VAM fungi in native saline soils.
Boyer, J. Plant productivity and environment. Science, Boss, P. Smithson, E. Frossand and A. Obserson, Microbial community composition and substrate use in a highly weathered soil as affected by crop rotation and P-fertilization. Lekberg and C. Zabinski, Arbuscular mycorrhizal fungi ameliorate temperature stress in the rmophilic plants. Ecology,