Arbuscular Mycorrhizas

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Timothy R. Cavagnaro - One of the best experts on this subject based on the ideXlab platform.

  • effects of plant roots and Arbuscular Mycorrhizas on soil phosphorus leaching
    Science of The Total Environment, 2020
    Co-Authors: Cuc T K Tran, Stephanie J Wattswilliams, Ronald J Smernik, Timothy R. Cavagnaro
    Abstract:

    While the impact of Arbuscular mycorrhizal fungi (AMF) on phosphorus (P) uptake is well understood, the mechanism(s) of how these fungi affect P leaching from soil is still unclear. Here we present results of a study in which we grew a mycorrhiza-defective tomato (Solanum lycopersicum L.) genotype (named rmc) and its mycorrhizal wild-type progenitor (named 76R) in microcosms containing non-sterile soil, to examine the influence of roots and AMF on P leaching. More P was leached from the planted microcosms as compared to the plant-free controls. Further, although there was more plant biomass and greater P uptake in the mycorrhizal plant treatments, these treatments were associated with the most leaching of total P, reactive P, and dissolved organic carbon (DOC). There was a strong correlation between the total P and DOC leached, suggesting that root and fungal exudates may have affected P leaching. These findings provide new insights into the impact of roots and AMF on nutrient leaching in soils.

  • ecological intensification and Arbuscular Mycorrhizas a meta analysis of tillage and cover crop effects
    Journal of Applied Ecology, 2017
    Co-Authors: Timothy M Bowles, Louise E Jackson, Malina Loeher, Timothy R. Cavagnaro
    Abstract:

    Summary 1.Reliance on ecosystem services instead of synthetic, non-renewable inputs is increasingly seen as key to achieving food security in an environmentally sustainable way. This process, known as ecological intensification, will depend in large part on enhancing below-ground biological interactions that facilitate resource use efficiency. Arbuscular Mycorrhizas (AM), associations formed between the roots of most terrestrial plant species and a specialized group of soil fungi, provide valuable ecosystem services, but the full magnitude of these services may not be fully realized under conventional intensively-managed annual agricultural systems. 2.Here we use meta-analysis to assess how reducing soil disturbance and periods without roots in agricultural systems affects the formation of AM and the diversity and community composition of Arbuscular mycorrhizal fungi (AMF). We compiled data from 54 field studies across five continents that measured effects of tillage and/or cover cropping on AMF colonization and/or communities and assessed effects of management and environmental factors on these responses. 3.Less intensive tillage and winter cover cropping similarly increased AMF colonization of summer annual cash crop roots by ~30%. The key variables influencing the change in AMF colonization were the type of cover crop or the type of alternative tillage, suggesting that farmers can optimize combinations of tillage and cover crops that most enhance AM formation, particularly with no-till systems and legume cover crops. 4.Richness of AMF taxa increased by 11% in low-intensity vs. conventional tillage regimes. Several studies showed changes in diversity and community composition of AMF with cover cropping, but these responses were not consistent. 5.Synthesis and applications. This meta-analysis indicates that less intensive tillage and cover cropping are both viable strategies for enhancing root colonization from indigenous Arbuscular mycorrhizal fungi (AMF) across a wide range of soil types and cash crop species, and possibly also shifting AMF community structure, which could in turn increase biologically-based resource use in agricultural systems. This article is protected by copyright. All rights reserved.

  • the role of Arbuscular Mycorrhizas in reducing soil nutrient loss
    Trends in Plant Science, 2015
    Co-Authors: Timothy R. Cavagnaro, Franz S Bender, Hamid R Asghari, Marcel G A Van Der Heijden
    Abstract:

    Substantial amounts of nutrients are lost from soils via leaching and as gaseous emissions. These losses can be environmentally damaging and expensive in terms of lost agricultural production. Plants have evolved many traits to optimize nutrient acquisition, including the formation of Arbuscular Mycorrhizas (AM), associations of plant roots with fungi that acquire soil nutrients. There is emerging evidence that AM have the ability to reduce nutrient loss from soils by enlarging the nutrient interception zone and preventing nutrient loss after rain-induced leaching events. Until recently, this important ecosystem service of AM had been largely overlooked. Here we review the role of AM in reducing nutrient loss and conclude that this role cannot be ignored if we are to increase global food production in an environmentally sustainable manner.

  • Arbuscular Mycorrhizas and Their Role in Plant Zinc Nutrition
    Soil Biology, 2014
    Co-Authors: Timothy R. Cavagnaro
    Abstract:

    Arbuscular Mycorrhizas play an important role in the acquisition of nutrients, including Zn. In this chapter, Zn uptake from the soil by Arbuscular mycorrhizal (AM) fungi, and delivery and transfer of Zn to plants, including discussion of the physiological and molecular processes involved, is considered. In addition to this, the importance of Arbuscular Mycorrhizas in plant Zn acquisition in agroecosystems is discussed with reference to the challenges of studying AM in the field. In doing so, knowledge gaps are identified, with the aim of stimulating future research in this fascinating aspect of the biology of AM.

  • uptake of zinc and phosphorus by plants is affected by zinc fertiliser material and Arbuscular Mycorrhizas
    Plant and Soil, 2014
    Co-Authors: Stephanie J Wattswilliams, Timothy R. Cavagnaro, Antonio F Patti, Terence W Turney
    Abstract:

    Background and Aims Water solubility of zinc (Zn) fertilisers affects their plant availability. Further, simultaneous application of Zn and phosphorus (P) fertiliser can have antagonistic effects on plant Zn uptake. Arbuscular Mycorrhizas (AM) can improve plant Zn and P uptake. We conducted a glasshouse experiment to test the effect of different Zn fertiliser materials, in conjunction with P fertiliser application, and colonisation by AM, on plant nutrition and biomass.

Stephanie J Wattswilliams - One of the best experts on this subject based on the ideXlab platform.

  • effects of plant roots and Arbuscular Mycorrhizas on soil phosphorus leaching
    Science of The Total Environment, 2020
    Co-Authors: Cuc T K Tran, Stephanie J Wattswilliams, Ronald J Smernik, Timothy R. Cavagnaro
    Abstract:

    While the impact of Arbuscular mycorrhizal fungi (AMF) on phosphorus (P) uptake is well understood, the mechanism(s) of how these fungi affect P leaching from soil is still unclear. Here we present results of a study in which we grew a mycorrhiza-defective tomato (Solanum lycopersicum L.) genotype (named rmc) and its mycorrhizal wild-type progenitor (named 76R) in microcosms containing non-sterile soil, to examine the influence of roots and AMF on P leaching. More P was leached from the planted microcosms as compared to the plant-free controls. Further, although there was more plant biomass and greater P uptake in the mycorrhizal plant treatments, these treatments were associated with the most leaching of total P, reactive P, and dissolved organic carbon (DOC). There was a strong correlation between the total P and DOC leached, suggesting that root and fungal exudates may have affected P leaching. These findings provide new insights into the impact of roots and AMF on nutrient leaching in soils.

  • uptake of zinc and phosphorus by plants is affected by zinc fertiliser material and Arbuscular Mycorrhizas
    Plant and Soil, 2014
    Co-Authors: Stephanie J Wattswilliams, Timothy R. Cavagnaro, Antonio F Patti, Terence W Turney
    Abstract:

    Background and Aims Water solubility of zinc (Zn) fertilisers affects their plant availability. Further, simultaneous application of Zn and phosphorus (P) fertiliser can have antagonistic effects on plant Zn uptake. Arbuscular Mycorrhizas (AM) can improve plant Zn and P uptake. We conducted a glasshouse experiment to test the effect of different Zn fertiliser materials, in conjunction with P fertiliser application, and colonisation by AM, on plant nutrition and biomass.

  • nutrient interactions and Arbuscular Mycorrhizas a meta analysis of a mycorrhiza defective mutant and wild type tomato genotype pair
    Plant and Soil, 2014
    Co-Authors: Stephanie J Wattswilliams, Timothy R. Cavagnaro
    Abstract:

    Background and aims Arbuscular Mycorrhizas (AM) enhance plant uptake of a range of mineral nutrients from the soil. Interactions between nutrients in the soil and plant, are complex, and can be affected by AM. Using a mycorrhiza-defective mutant tomato genotype (rmc) and its wild-type (76R), provides a novel method to study AM functioning.

  • Arbuscular Mycorrhizas are beneficial under both deficient and toxic soil zinc conditions
    Plant and Soil, 2013
    Co-Authors: Stephanie J Wattswilliams, Antonio F Patti, Timothy R. Cavagnaro
    Abstract:

    Background and aims Arbuscular Mycorrhizas (AM) play different roles in plant Zn nutrition depending on whether the soil is Zn-deficient (AM enhancement of plant Zn uptake) or Zn-toxic (AM protection of plant from excessive Zn uptake). In addition, soil P concentration modifies the response of AM to soil Zn conditions. We undertook a glasshouse experiment to study the interactive effects of P and Zn on AM colonisation, plant growth and nutrition, focusing on the two extremes of soil Zn concentration—deficient and toxic.

  • Arbuscular Mycorrhizas modify tomato responses to soil zinc and phosphorus addition
    Biology and Fertility of Soils, 2012
    Co-Authors: Stephanie J Wattswilliams, Timothy R. Cavagnaro
    Abstract:

    Arbuscular Mycorrhizas (AM) play an important role in plant P and Zn nutrition; however, relatively few studies have directly investigated the interactive effects of these nutrients on plants. Therefore, we undertook a glasshouse experiment to study the effects of Zn and P on AM formation and functioning. A mycorrhiza defective tomato mutant (rmc) and its mycorrhizal wild-type progenitor (76R) were used in this experiment. Plants were grown in soil amended with five Zn concentrations, ranging from deficient to toxic, and two levels of P addition. The addition of Zn and P to the soil over a range of concentrations had profound effects on plant growth and nutrition and mycorrhizal colonization. Mycorrhizal benefits were the greatest when plants were grown under low soil P and Zn. Furthermore, the effect of soil Zn supply on plant growth, nutrition, and AM colonization was strongly influenced by the concentration of P in the soil. Thus, studies of AM and Zn (or other nutrients of interest) should take into account the impact of soil P concentration on the role of AM in plant Zn acquisition, under both deficient and toxic soil Zn concentrations.

Zhao Zhiwei - One of the best experts on this subject based on the ideXlab platform.

  • occurrence of Arbuscular Mycorrhizas and dark septate endophytes in hydrophytes from lakes and streams in southwest china
    International Review of Hydrobiology, 2006
    Co-Authors: Zhao Zhiwei
    Abstract:

    In this study, the colonization of Arbuscular Mycorrhizas (AM) and dark septate endophytes (DSE) in 140 specimens of 32 hydrophytes collected from four lakes and four streams in southwest China were investigated. The Arbuscular mycorrhizal fungi (AMF) and DSE colonization in these hydrophytes were rare. Typical AM structures were observed in one of the 25 hydrophytic species collected in lakes and six of the 17 species collected in streams. Spores of 10 identified AMF species and an unidentified Acaulospora sp. were isolated from the sediments. The identified AMF came from the four genera, Acaulospora, Gigaspora, Glomus and Scutellospora . Glomus and G. mosseae were the dominant genus and species respectively in these aquatic environments. The presence of DSE in hydrophytes was recorded for the first time. DSE occurred in one of the 25 hydrophyte species collected in lakes and three of the 17 species collected in streams. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

  • Arbuscular Mycorrhizas in a hot and arid ecosystem in southwest china
    Applied Soil Ecology, 2005
    Co-Authors: Zhao Zhiwei
    Abstract:

    Abstract The colonization by Arbuscular mycorrhizal fungi, Arbuscular mycorrhizal fungal spore abundance and community were investigated in a valley-type semi-savanna vegetation of Yuan River in southwest China. Of the 62 plants representing 33 families surveyed, 59 plant species (about 95%) were Arbuscular mycorrhizal and 3 species (5%) were possibly Arbuscular mycorrhizal. Rhizosphere soils harbored abundant Arbuscular mycorrhizal fungal spores in a range of 240–6430 per 100 g soil with an average of 2096, and most spores were small with diameter less than 70 μm (about 78%). The fungi most frequently found were members of the genera Acaulospora and Glomus . Acaulospora spinosa , A. denticulata , A. tuberculata , Glomus sinuosa , G. clarum , G. intraradices and G. microaggregatum were the most common species. These results revealed that Arbuscular Mycorrhizas are a common and important component in this semi-savanna vegetation; the high spore density and colonization were presumably a selective adaptation toward the hot and arid ecosystem.

  • Arbuscular Mycorrhizas in a valley type savanna in southwest china
    Mycorrhiza, 2004
    Co-Authors: Li Jianping, Zhao Zhiwei
    Abstract:

    The Arbuscular mycorrhizal (AM) status of 67 plant species in a savanna community in the hot, dry valley of Jinsha River, southwest China was surveyed. It was found that about 95% of the plant species formed AM and 5% possibly formed AM. The composition of AM fungi (AMF) in the rhizosphere soils was also investigated. The AMF spore density ranged from 5 to 6,400 per 100 g soil, with an average of 1,530, and these spores/sporocarps were identified as belonging to six genera. Fungi belonging to the genera Glomus and Acaulospora were the dominant AMF. High densities of AMF spores in the rhizosphere soils, and the intensive colonization of the plant roots, indicated that plants grown in this valley-type savanna may be highly dependent on AM.

  • Arbuscular Mycorrhizas in the Dry-Hot Valley of Jinsha River
    Acta Botanica Yunnanica, 2003
    Co-Authors: Zhao Zhiwei, Ren Licheng, L. J. Anpin
    Abstract:

    The Arbuscular mycorrhizal status of 60 plant spe c ies growing in the dry-hot valley of Jinsha River was surveyed by means of acid fuchsin stain after the roots were lysised in alkaline solution. It was found th at 70% of the species were Arbuscularly mycorrhized. Most of the constructive spe cies of the natural plant community and some species in Cyperaceae and Polygonac eae have Arbuscular Mycorrhizas. Arbuscular mycorrhiza is an important component in the dry-hot valley ecosystem. Thus it is essential to restore the vegetation of the dry-hot valley.

  • The Arbuscular Mycorrhizas of pteridophytes in Yunnan, southwest China: evolutionary interpretations
    Mycorrhiza, 2000
    Co-Authors: Zhao Zhiwei
    Abstract:

    The percentage of Arbuscular mycorrhizal pteridophytes among 256 pteridophyte species distributed in Yunnan (southwest China) was found to be lower than that in angiosperms. In the pteridophytes, the occurrence of Arbuscular Mycorrhizas was low in sporophytes of fern-allies and leptosporangiates, whereas in the eusporangiates it was relatively high. From the standpoint of mycotrophism, the evolutionary trend in the Filicineae may be from constantly mycorrhizal to facultative mycorrhizal and finally to nonmycorrhizal plants.

Sally E. Smith - One of the best experts on this subject based on the ideXlab platform.

  • Mycorrhizal Symbiosis (Second Edition) - Genetic, cellular and molecular interactions in the establishment of Arbuscular Mycorrhizas
    Mycorrhizal Symbiosis, 2020
    Co-Authors: Sally E. Smith, David Read
    Abstract:

    Publisher Summary Development of Arbuscular Mycorrhizas (AM) involves a well-synchronized sequence of events, during which morphogenetic changes to both fungus and plant take place, supporting the maintenance of a compatible, biotrophic symbiosis. This chapter discusses the genetic, cellular, and molecular interactions in the establishment of Arbuscular Mycorrhizas. Research in the last 10 years has revolutionized our understanding of genetic programming and control of AM colonization, although much detail remains to be revealed. The development of Arbuscular Mycorrhizas is under the control of plant and fungal genes, which act in a coordinated manner to produce the characteristic, biotrophic, and compatible interaction in AM plants. It is possible to describe the colonization process in precise terms and with the help of increasing numbers of mutants, identify key regulatory steps and some of the genes that control them. Signaling between the symbionts, particularly prior to contact, is now confirmed, and the identification of the molecules involved is likely to lead to much increased understanding of both the receptors with which the signals interact and of the roles of signals and receptors in facilitating integrated symbiotic development, as well as in conferring plant–fungus selectivity or specificity. Major advances have also been made in showing how gene expression is altered in both symbionts. The reasons the AM fungi, which have many similarities with damaging plant pathogens, fail to trigger major defense responses in plants have intrigued researchers for many years. In AM symbioses, some defense responses are apparently mobilized for a short period but are later suppressed.

  • the symbionts forming Arbuscular Mycorrhizas
    Mycorrhizal Symbiosis (Third Edition), 2008
    Co-Authors: Sally E. Smith, David Read
    Abstract:

    This chapter focuses on fungi symbionts that form Arbuscular Mycorrhizas (AM). AM are the most common mycorrhizal type. They are formed in an enormously wide variety of host plants by obligately symbiotic fungi, which have recently been reclassified on the basis of DNA sequences into a separate fungal phylum, the Glomeromycota. The plants include angiosperms, gymnosperms, and the sporophytes of pteridophytes, all of have roots, as well as the gametophytes of some hepatics and pteridophytes, which do not. Through their roles in nutrient uptake, AM fungi were probably important in the colonization of land by plants and they remain major determinants of plant interactions in ecosystems to the present day. The name “Arbuscular” is derived from characteristic structures, the arbuscules, which occur within the cortical cells of many plant roots, and also some mycothalli colonized by AM fungi. An Arbuscular mycorrhiza has three important components: the root itself, the fungal structures within and between the cells of the root, and an extraradical mycelium in the soil. AM fungi have been recognized as obligate symbionts of a very wide range of plant species. The symbioses are biotrophic and normally mutualistic, the long-term compatible interactions being based largely on bidirectional nutrient transfer between the symbionts, sometimes supplemented by other benefits such as drought and disease tolerance. There is increasing evidence for specificity or selectivity of some plant species for particular fungal symbionts. Non-mycorrhizal plants and plants which form more than one type of mycorrhiza are found in a number of families, supporting the idea that loss of AM status or gain of another type of mycorrhiza has evolved many times, probably as a result of different selection pressures and based on different mechanisms.

  • colonization of roots and anatomy of Arbuscular Mycorrhizas
    Mycorrhizal Symbiosis (Third Edition), 2008
    Co-Authors: Sally E. Smith, David Read
    Abstract:

    This chapter provides an account of the main characteristics of Arbuscular mycorrhizal (AM) roots of different types and shows how they develop from sources of in the soil. Colonization of roots by AM fungi can arise from three main sources of inoculum in soil: spores, infected root fragments, and hyphae—collectively termed propagules. Based on the variations in morphology of colonization AM have been classified as Arum- and Paris-type Mycorrhizas. In Paris-type Mycorrhizas, cortical colonization of roots is characterized by extensive development of intracellular coiled hyphae, which spread directly from cell to cell. While in Arum-type associations the fungus spreads relatively rapidly in the root cortex by intercellular hyphae, which extend along well-developed intercellular air spaces. Regardless of morphology, AM colonization of roots can be initiated from hyphae growing from any of the three sources of inoculum. Primary colonization of roots from discrete propagules can be initiated from as far away as 13 mm. Hyphal contact with the root is usually followed by adhesion of the hypha to the root surface and, after about 2–3 days, the formation of swollen appressoria. Following the formation of an appressorium and penetration of the epidermis and exodermal cells, infection units develop in both Arum-type and Paris-type Mycorrhizas. The outcome of the colonization process is that the fungus comes to occupy two different apoplastic compartments in the root, the intercellular spaces between cortical cells, and a more specialized intracellular apoplast, surrounding arbuscules or coils. These interfaces play critical roles in bidirectional nutrient transfers between the symbionts. The morphological structures formed by the fungi, particularly in the root cortex, are highly varied and include both “classic” arbuscules as well as less well-known and understood intracellular coils and arbusculate coils.

  • Arbuscular Mycorrhizas influence plant diversity and community structure in a semiarid herbland
    New Phytologist, 2002
    Co-Authors: Patrick Oconnor, Sally E. Smith, Andrew F Smith
    Abstract:

    Summary • The contribution of Arbuscular Mycorrhizas (AM) to plant community structure and diversity is reported here in an annual herbland in southern Australia. • Mycorrhizal colonization was reduced in field plots by applying the fungicide benomyl as a soil drench. The mycorrhiza-responsiveness of plant species was assessed in intact soil cores containing the indigenous AM fungi and in a pot experiment using an isolate of Glomus mosseae. • Glasshouse experiments showed that Medicago minima, Vittadinia gracilis and Velleia arguta were highly mycorrhiza-responsive, Salvia verbenaca became colonized but exhibited no growth response to AM, and Carrichtera annua remained uncolonized. There was no change in plant species richness in mycorrhiza-suppressed field plots but diversity increased owing to an increase in evenness. Treatment had no effect on community productivity and therefore there was no relationship between mycorrhizal effects on diversity and productivity. • Mycorrhizal responsiveness was not a good predictor of species response to suppression of AM in the field. The mycorrhiza-responsive species V. gracilis and V. arguta were not affected by reduced mycorrhizal colonization in fungicide-treated plots, suggesting that competition from the mycorrhiza-responsive dominant M. minima offset the benefits of mycorrhizal association for these species.

  • morphology of Arbuscular Mycorrhizas is influenced by fungal identity
    New Phytologist, 2001
    Co-Authors: Timothy R. Cavagnaro, F A Smith, Sally E. Smith
    Abstract:

    Summary • There are two main morphological types of Arbuscular Mycorrhizas (AM), the Arum-type and the Paris-type. It is often accepted that AM morphology is controlled by plant identity. • In this experiment the influence of fungal identity on the morphology of AM was investigated. Wild-type (76R) tomato (Lycopersicon esculentum) was grown in association with six different AM fungal species in nurse pots. The morphology of the AM was assessed quantitatively using the magnified intersects technique. • Three of the fungal species (Glomus intraradices, G. mosseae, G. versiforme) formed the Arum-type, with characteristic intercellular hyphae and arbuscules. The remaining three species (Gigaspora margarita, Glomus coronatum, and Scutellospora calospora) formed the Paris-type, with hyphal and arbusculate coils. • The results demonstrate that the morphology of AM is not solely under plant control but is also influenced by fungal identity. Possible reasons for the differences observed and the functional implications are discussed.

A H Fitter - One of the best experts on this subject based on the ideXlab platform.

  • does elevated atmospheric carbon dioxide affect Arbuscular Mycorrhizas
    Trends in Ecology and Evolution, 1998
    Co-Authors: Philip L Staddon, A H Fitter
    Abstract:

    Abstract It is well established that an increase in the concentration of atmospheric CO 2 stimulates plant growth. Recently, many researchers have concluded that elevated CO 2 concentrations also stimulate mycorrhizal colonization. However, new evidence suggests that the observed CO 2 effects on Arbuscular mycorrhizal fungi are indirect and are a result of faster plant growth at higher CO 2 concentrations. Potential changes to species assemblages of mycorrhizal fungi could affect soil carbon storage and, consequently, the feedback effects of terrestrial soil–vegetation systems on global environmental change.

  • multi functionality and biodiversity in Arbuscular Mycorrhizas
    Trends in Ecology and Evolution, 1995
    Co-Authors: K K Newsham, A H Fitter, A R Watkinson
    Abstract:

    Abstract Plant roots in natural ecosystems are typically colonized by a wide range of fungi. Some of these are pathogenic, others appear to be opportunistic and have no apparent impact, while mycorrhizal fungi are generally regarded as mutualistic. Of the various types of mycorrhizal fungi, the Arbuscular mycorrhizal (AM) association is by far the most abundant and widespread. While the most widely accepted model of AM function depends upon plants benefiting from the facilitation of phosphorus uptake, recent data from field-based studies in temperate ecosystems indicate that only plant species with poorly branched root systems benefit from AM fungi in this way: species with highly branched root systems may benefit in other ways, such as by being protected against root pathogenic fungi. These two responses apparently represent extremes along a continuum of AM benefit determined by root system architecture.

  • diversity of fungal symbionts in Arbuscular Mycorrhizas from a natural community
    New Phytologist, 1995
    Co-Authors: Justin P Clapp, J P W Young, James Merryweather, A H Fitter
    Abstract:

    summary The Arbuscular mycorrhizal (AM) association between fungi in the order Glomales and the roots of a very wide range of vascular plants is of global ecological significance but has proved particularly intractable to study in the field. We have developed a reliable technique to identify the fungal symbionts in roots taken directly from natural communities. Selective Enrichment of Amplified DNA combines the use of recently-developed specific DNA primers with a novel method based on the principle of subtractive hybridization to remove interfering plant-derived DNA after amplification with the polymerase chain reaction. Using this technique we have shown that endoMycorrhizas of bluebells (Hyacinthoides non-scripta) sampled directly from a woodland habitat are multispceies communities of varying composition which contain at least three genera of mycorrhizal fungi. The technique works well on a range of plant species and should have wide application to the identification of other symbionts, including pathogens. A spore survey has indicated that two particular AM types are associated with bluebells and this observation corroborates the molecular data. The presence of a Glomus species in bluebell roots was not expected from the spore data.

  • the distribution of Arbuscular Mycorrhizas in the british flora
    New Phytologist, 1993
    Co-Authors: H J Peat, A H Fitter
    Abstract:

    SUMMARY Arbuscular mycorrhizal (AM) associations with higher plants are common in many ecosystems but some plant species are consistently never or rarely infected. These species may differ morphologically or occur in different habitats from species which are usually mycorrhizal. A large data-set on the ecology of British angiasperms was used to test for relationships between the mycorrhizal status of British angiosperms and several morphological and environmental variables (life form, root diameter, seed weight, soil fertility, soil water availability, soil pH and habitat type). No relationship was found between soil fertility or soil water availability and frequency of infection with AM fungi. AM species, however, can grow in habitats with a higher pH than non-mycorrhizal species and perennial AM species occur in a significantly greater number of habitat types than perennial species which are never, or rarely, Arbuscular mycorrhizal. Non-mycorrhizal species tend to have thinner roots, smaller seeds and occur mainly in aquatic, wetland and saline habitats.

  • the role of ecological significance of vesicular Arbuscular Mycorrhizas in temperate ecosystems
    Agriculture Ecosystems & Environment, 1990
    Co-Authors: A H Fitter
    Abstract:

    Abstract Although vesicular-Arbuscular Mycorrhizas (VAM) are abundant and widespread in many vegetation types, the levels of infection vary widely between species and sites. This is inconsistent with the usual explanation of their role and a number of possible alternative hypotheses are examined. Results of experimental manipulations suggest that for much of the time, plants receive little benefit from VAM. It is suggested that most plants only derive benefits at times when their demand for P is much greater than the capacity of their root systems to supply it. Flowering and seedling establishment may be examples of such times for many plants.