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Ruotsalainen, Anna Liisa. "Mycorrhizal colonization and plant performance in arcto-alpine conditions /." Oulu [Finland] : Oulun Yliopisto, 2003. http://herkules.oulu.fi/isbn9514269888/html/index.html.
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Cavagnaro, Timothy R. "Structure and physiology of Paris-type arbuscular mycorrhizas." Title page, contents and abstract only, 2001. http://web4.library.adelaide.edu.au/theses/09PH/09phc376.pdf.
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Ike-Izundu, Nnenna Esther. "Interaction between arbuscular mycorrhizal fungi and soil microbial populations in the rhizosphere." Thesis, Rhodes University, 2008. http://hdl.handle.net/10962/d1004021.
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This study examined the rehabilitation potential of AM fungi with organic and inorganic fertilisers under pot and field trial conditions as well as their interaction with rhizospheric organisms and specific functional groups. In addition, the study highlighted the effects of land-use management on AM fungal populations in soil and the mycorrhizal status of some selected plants from one of the study sites. The study focussed on two sites that differ in operational activities and these included a mined area that was to be rehabilitated and a commercial farming site. A pot trial was conducted using an overburdened soil resulting from kaolin clay mining. Pots were seeded with Cynodon dactylon and treated with either Organic Tea or NPK (3:1:5) fertiliser, with or without AM fungal inoculum. The compatibility of these fertilisers with AM fungi was assessed by plant growth and percentage root colonisation. Maximum shoot height and plant biomass were observed at the 28th week with NPK (3:1:5) fertiliser supporting mycorrhizal colonisation by 80%. The result indicated the potential of AM fungi to be used in rehabilitation with minimal phosphate fertiliser. Similarly, a field trial was set-up using 17 x 17 m[superscript 2] plots in the mining site that were treated with the same organic and inorganic fertilisers as well as with AM fungal inoculum in different combinations. The interaction between AM fungi and soil microbial population was determined using culture dependent and culture independent techniques. The culture dependent technique involved the use of soil dilution and plating on general purpose and selective media. The result showed that there was no change in the total culturable bacterial number in the untreated and AM fungal treated plots, while a change in species composition was observed in the functional groups. Different functional groups identified included nitrogen fixing bacteria, pseudomonads, actinomycetes, phosphate solubilisers and the fungal counterparts. Gram-positive bacteria were observed as the predominant phenotypic type, while nitrogen fixers and actinomycetes were the predominant functional groups. Species identified from each functional group were Pseudomonas fulva, Bacillus megaterium, Streptomyces and actinomycetales bacteria. Meanwhile, fungi such as Ampelomyces, Fusarium, Penicillium, Aspergillus, Cephalosporium and Exserohilium were identified morphologically and molecularly. Furthermore, the mining site had a significantly higher bacterial number than the farming site thereby indicating the effects of land-use management on culturable bacterial numbers. The culture independent technique was carried out by cloning of the bacterial 16S rDNA and sequencing. Identified clones were Bradyrhizobium, Propionibacterium and Sporichthya. A cladogram constructed with the nucleotides sequences of identified functional species, clones and closely related nucleotide sequences from the Genbank indicated that nucleotide sequences differed in terms of the method used. The activity and establishment of the introduced AM fungal population was determined by spore enumeration, infectivity assay, percentage root colonisation and assessment of glomalin concentrations. The results indicated that the two land use types affected AM fungal populations. However, the establishment of AM fungi in the farming site was more successful than in the mining site as indicated by the higher infectivity pontential. Selected host plants, which were collected around the mine area, were observed to be mainly colonised by AM fungi and these were identified as Pentzia incana, Elytropappus rhinocerotis, Euphorbia meloformis, Selago corymbosa, Albuca canadensis and Helichrysum rosum. These plant species were able to thrive under harsh environmental conditions, thereby indicating their potential use as rehabilitation host plants. Generally, the findings of this study has provided an insight into the interaction between arbuscular mycorrhizal fungi and other soil microorganisms in two fields with differing land use management practices.
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Dhillion, Shivcharn S. Anderson Roger C. "Mycorrhizas and mycorrhizal little bluestem grass (Schizachyrium scoparium) on burned and unburned sand prairies." Normal, Ill. Illinois State University, 1991. http://wwwlib.umi.com/cr/ilstu/fullcit?p9203026.
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Thesis (Ph. D.)--Illinois State University, 1991.Title from title page screen, viewed December 6, 2005. Dissertation Committee: Roger C. Anderson (chair), Anthony E. Liberta, R. Michael Miller, Tsan Iang Chuang, Jerome R. Cain. Includes bibliographical references (leaves 104-113) and abstract. Also available in print.
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Pivato, Barbara. "Ecology of arbuscular mycorrhizas : interactions plant - fungal genotypes and mycorrhizas - bacteria." Dijon, 2008. http://www.theses.fr/2008DIJOS006.
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La première étape de la thèse a consisté à comparer la diversité et la structure génétique des populations de champignons mycorhiziens à arbuscules (MA) associées à quatre espèces de médiques annuelles. Les résultats obtenus montrent que l’abondance des champignons MA différait, indiquant que la structure génétique de la communauté fongique a été influencée par l’espèce végétale. La deuxième étape de ce travail visait à tester l’hypothèse selon laquelle la longue histoire évolutive entre champignons MA et plantes ne se serait pas faite de façon indépendante des bactéries. La structure génétique des populations bactériennes associées aux racines mycorhizées et non de M. Truncatula a été comparée. Les communautés bactériennes différaient de façon significative, ces différences étant expliquées par des marqueurs moléculaires associés aux familles des Oxalobacteraceae et Comamonadaceae. Six isolats représentatifs des populations associées aux racines mycorhizées et deux souches de référence (Collimonas fungivorans Ter331 et Pseudomonas fluorescens C7R12) ont été testées afin de déterminer leur effet sur la mycorhization. Une souche appartenant aux Oxalobacteraceae (Collimonas sp. J5B4) et P. Fluorescens C7R12 ont amélioré la croissance du champignon AM et sa colonisation racinaire, confirmant partiellement l’hypothèse que les bactéries associées aux racines mycorhizées auraient un effet favorable sur la mycorhization. Enfin, la caractérisation de l’effet promoteur de P. Fluorescens C7R12 sur la mycorhization a montré que cet effet était spécifique du champignon MA et que la colonisation des cellules bactériennes différait sur les racines mycorhizées et non-mycorhizéesIn the first part of the thesis, possible effect of the plant genotype on the genetic diversity and structure of the arbuscular mycorrhizal (AM) fungal community was assessed. Results indicated a similar diversity of AM fungi in the four Medicago species used. However, the abundance of AM fungi differed significantly upon the plant species, indicating preferential associations between AM fungal and plant genotypes. The second part of the thesis was based on the hypothesis that the long joint evolution of AM fungi and plants did not occur independently of the associated bacteria. To test this hypothesis, the genetic structure of bacterial communities associated with mycorrhizal and non mycorrhizal roots of M. Truncatula was compared. The bacterial communities differed significantly between mycorrhizal and non mycorrhizal roots, these differences being explained by sequences belonging to Oxalobacteraceae and Comamonadaceae families. Six bacterial isolates representative of the populations belonging to Oxalobacteraceae and Comamonadaceae were tested together with two reference strains (Collimonas fungivorans Ter331 and Pseudomonas fluorescens C7R12) for their effect on mycorrhization. One strain belonging to Oxalobacteraceae (Collimonas sp. J5B4) and P. Fluorescens C7R12 promoted both AM fungal growth and mycorrhization, partially confirming our hypothesis that bacteria preferentially associated with mycorrhizal roots would be beneficial to the symbiosis. Finally, the characterization of the promoting effect of P. Fluorescens C7R12 showed that it was fungal specific and that the pattern of colonization of bacterial cells on mycorrhizal and non mycorrhizal roots differed
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Skinner, Amy. "Investigating the effect of Glomus etunicatum colonization on structure and phloem transport in roots of Eragrostis curvula (Umgeni)." Thesis, Rhodes University, 2007. http://hdl.handle.net/10962/d1003796.
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The symbiotic unit of an arbuscular mycorrhizal fungus and its host is able toachieve and maintain far higher inflow of nutrients than non-mycorrhizal roots. The colonization strategy of the mycobiont within the plant is intrinsic to the symbiosis with respect to both structural adaptations and nutrient exchange. An investigation into the effect of Glomus etunicatum colonization on the structure and phloem transport in Eragrostis curvula (Umgeni) allowed for greater insight into the dynamic of the symbiosis. The combined use of stains (such as Trypan Blue, Chlorazol Black, Safranin and Fast Green), and techniques, (such as freeze-microtome transverse sectioning and permanent slide preparations) contributed to a successful general observation of an intermediate colonization strategy using light microscopy methods. However, clarity into structural detail of mycorrhizal forms required electron microscopy studies. The SEM method used with freeze fracture was a relatively quick and simple method allowing for the observation of surface and internal features. The TEM method allowed for highresolution images providing insight into the variations in the apoplasmic compartmental form, and how this may relate to the function of the symbiosis with regard to fungal coils or arbuscules. The apoplasmic nature of mycorrhizas was substantiated and no symplasmic connections were found between symbionts. Fluorescence studies demonstrated that 5,6-carboxyfluorescein was transported through the phloem into the roots of E. curvula, but remained predominantly in the root phloem. Unloading only occurred in optimal nutrient exchange areas of meristimatic lateral or apical growth regions. It was not possible, using fluorescence techniques and related equipment available, to conclusively establish if there were symplasmic connections between the mycobiont and its host or if bidirectional transfer of nutrients occurred at the same interface.
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Facelli, Evelina. "The role of mycorrhizal symbiosis in plant intraspecific competition and population structure." Title page, Contents and Abstract only, 1998. http://hdl.handle.net/2440/37773.
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The overall objective of this project was to investigate the effects of the symbiotic association of plants with vesicular - arbuscular mycorrhizal fungi on the intensity of intraspecific competition and its consequences on population structure I performed four main glasshouse experiments using a non - cultivated species, Rhodanthe chlorocephala ssp rosea, or a cultivated species, Trifolium subterraneum. I grew the plants at different plant densities, under different levels of resources ( phosphorus and / or light ), in environments with homogeneous and / or patchy distribution of phosphorus ( P ). In pots with homogeneous distribution of P, the addition of P to R. chlorocephala and mycorrhizal infection in T. subterraneum increased plant biomass of single plants. However, these beneficial effects were reduced by increasing plant density. Shading of plants of T. subterraneum did not generally alter these effects. Mycorrhizal symbiosis and the addition of P always increased the intensity of plant intraspecific competition. In trays with patchy or homogeneous distribution of P, mycorrhizal infection and patchy distribution of P increased the total biomass and size inequality of populations of plants of T. subterraneum. Individual biomass was determined by the local soil P concentration in patchy environments and by mycorrhizal infection in low density treatments. Mycorrhizal infection, but not patchy P distribution, increased relative competition intensity. Asymmetric or symmetric distribution of resources between plants will change these size hierarchies. The distinction between these two types of distributions has lead to two different models explaining the interaction between competition and size inequality ( degree to which the biomass is concentrated within a small fraction of the population &# 40 Weiner and Thomas 1986 ) ) the resource depletion and resource pre - emption models ( Weiner and Thomas 1986, Weiner 1988b ). In the first model ( resource depletion ) competition reduces the relative growth rate of all the individuals by the same proportion, reduces variance of growth rates and reduces variation in sizes. Thus, in this model resource acquisition is proportional to plant size ( Weiner 1990 ). This model is also called symmetric or two - sided competition and applies when competition for nutrients predominates. It predicts that at high density, plants will be smaller but the population will have less inequality than at low density ( Weiner and Thomas 1986 ). In the second model ( resource pre - emption ), competition increases the variation in relative growth rates and increases variation in sizes. Large plants obtain a more than proportional share of the resources ( relative to sizes ) ( Weiner 1990 ) and this increases their competitive ability which results in a positive feedback on plant size. This phenomenon is also called snowball cumulation, asymmetric or one - sided competition and it was observed only when competition for light was predominant ( Wilson 1988a ). This second model predicts that at high density plant populations will have more inequality than at low density ( Weiner and Thomas 1986 ). Although these two models are generally accepted, alternative analyses and recent experiments show that the degree of asymmetry of the interaction depends on the spatial and temporal distribution of the resource, the spatial distribution of the individuals in the population, neighbourhood competition and the mobility of the resource ( Huston 1986 ; Miller and Weiner 1989, Weiner 1990, Bonan 1991 ). Weiner ( 1990 ) suggested that if nutrients are distributed homogeneously and the uptake is proportional to root size, the competitive interaction will be more symmetric, whereas if patches with more nutrients can be reached by large individuals, asymmetric competition will predominate. This hypothesis has not been tested yet. Turner and Rabinowitz ( 1983 ) found that populations with an initial random spatial distribution of individuals had an unexpected increase in size inequality. My results emphasise that the main effects of mycorrhizas at the individual level cannot be expected to be apparent at the population level, because of the influence of density - dependent processes. However, infected individuals with a strong response to the symbiosis would have an advantage in situations of competition. This scenario can explain the maintenance of the symbiotic ability even under conditions such as dense populations, where there is no obvious advantage of the symbiosis at the population level.Thesis (Ph.D.)--Department of Soil and Water, 1998.
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Haller, Anjanette H. A. "The presence and role of arbuscular mycorrhizal fungi in coastal sand dune systems." Thesis, Rhodes University, 2000. http://hdl.handle.net/10962/d1003765.
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Arbuscular mycorrhizas (AM) are mutually beneficial symbiotic associations between the roots of plants and certain Zygomycetous fungi. The role of AM fungi in coastal sand dunes has been explored in many parts of the world, though little work has been conducted in South African dune systems. This study aimed to investigate the presence and extent of mycorrhizal colonisation of a coastal sand dune in South Africa. The roots of five plant species (Scaevola plumieri, Arctotheca populifolia, Ipomoea pes-caprae, Ehrharta villosa and Chrysanthemoides monilifera) were sampled along a foredune profile at Old Woman's River in the Eastern Cape. These roots were assessed for the percentage mycorrhizal colonisation they supported. Spores extracted from the rhizosphere sand of each plant species were counted and identified to genus level. Results were related to seasonality and the position of the plants along the profile. All plant species were found to be mycorrhizal. Percentage colonisation ranged from 0-92%, depending on plant species and season. Mycorrhizal colonisation was generally highest in the winter months, and especially so in I pes-caprae and E. villosa. The extent of various mycorrhizal structures in root tissue varied between plant species. Spore numbers ranged from 0-48 spores 100g-1 sand with highest numbers occurring in winter. S. plumieri and A. populifolia were associated with greatest spore abundance. Four fungal genera (Glomus, Acaulospora, Scutellospora and Gigaspora) were identified. Distribution of these genera showed seasonal variations between plant species. A bioassay, using Sorghum, was conducted to test the inoculum potentials of sand from the Scaevola hummock and the IpomoealEhrharta dune. Highest percentage colonisation occurred in plants grown in the Scaevola sand, which also had the lowest root and shoot measurements. The bioassay confirmed that AM propagules are present and viable, even in the mobile sand of the foredune. This study showed that mycorrhizal colonisation and spore numbers varied seasonally, but that the extent of this was dependent on plant species. The position of plants along the foredune profile tended to be less important than plant species. It is thought that the growth cycle and rooting system of each plant species determines seasonal cycles and abundance of AM fungi. Variation within fungal populations probably also impacts on this. Knowledge of the presence and distribution of AM fungi in this system paves the way for more detailed studies which need to examine the role of these endophytes in South African sand dunes.
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Rains, Kai Coshow. "Ericoid mycorrhizas in organic substrates : distribution of ericoid mycorrhizas among epiphytes in a Costa Rican cloud forest and uptake of organic nitrogen by ericoid, ecto-, and arbuscular mycorrhizal pygmy forest plants /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2004. http://uclibs.org/PID/11984.
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Boulet, Frederic. "Mycorrhizal symbiosis as a strategy for survival in ultramafic soils." University of Western Australia. Soil Science and Plant Nutrition Discipline Group, 2003. http://theses.library.uwa.edu.au/adt-WU2004.0051.
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Ultramafic soils enriched in nickel, such as found in Australia and New Caledonia, are associated with unique, diverse and poorly known vegetation communities. Re-establishment of these highly specific ecosystems is still a challenge for Ni mining companies. Ultramafic vegetation communities are the outcome of a long evolution process resulting in their adaptation to the extreme soil conditions found on ultramafic outcrops. Mycorrhizal fungi, a very common plant symbiont, are generally thought to be beneficial to plants in other ecosystems, providing plants with phosphorus and even promoting metal tolerance in plants in some cases. We examined the hypothesis that mycorrhizal fungi may contribute to the survival of plants in ultramafic soil conditions. Bandalup Hill, an ultramafic outcrop enriched in Ni (South West of Western Australia) was selected to assess the contribution of mycorrhizal fungi to ultramafic plants. Soil constraints, in particular the degree of Ni toxicity, were assessed at two sites with ultramafic soils within the outcrop. Total metal, nutrient, DTPA extractable Ni and available P were measured in soil while Ni, Ca and Mg were tested in the soil solution. In addition, nutrients and metals were analyzed in shoots of some plant species occurring at each site: Eucalyptus flocktoniae, Melaleuca pomphostoma, Melaleuca coronicarpa and Hakea verucosa. Topsoils in Bandalup Hill and plant shoots had high levels of Ni, and very low levels of P, K and N. Variation in DTPA extractable Ni between sites reflected the variation in shoot Ni level of E. flocktoniae and M. pomphostoma. Variations in soil solution Ni levels reflected variations in shoot Ni levels of M. coronicarpa and H. verucosa between sites. The germination requirements of the plant species used to assess the soil constraints was assessed. Species selected included Eucalyptus flocktoniae, Melaleuca coronicarpa, and Hakea verucosa. Seeds of E. flocktoniae and M. coronicarpa had a higher germination rate if pre-treated with smoke water, while no pre-treatment was required to germinate H. verucosa seeds. The unusual germination requirement of E. flocktoniae and M. coronicarpa involve complex chemical signals that may be present in the soil when the conditions are more favorable for plant establishment. Such unusual germination requirement may represent an adaptation to the hostile conditions of the ultramafic soils of Bandalup Hill. The mycorrhizal association and root characteristics of the selected plant species was also assessed after 8 weeks of growth in undisturbed ultramafic topsoil cores from Bandalup Hill. Roots of these species (including H. verucosa from a previously designated non-mycorrhizal family, Proteaceae) were associated with mycorrhizal fungi. Roots of E. flocktoniae and M. coronicarpa were colonized by both arbuscular mycorrhizal fungi (AMF) and ectomycorrhizal fungi (ECM), while roots of H. verucosa only contained some AM fungal structures. All species had high shoot to root ratios and their root characteristics reflected their association with mycorrhizal fungi. Based on the previous observations, uninoculated and inoculated E. flocktoniae seedlings were grown for 10 to 16 weeks in sand amended with Ni at 0, 0.2, 1 and 2.3 mg/kg. Mycorrhizal inoculum consisted of spores of Pisolithus sp. (ECM) or a mix of AMF spores and colonized root fragments, both originating from Bandalup Hill. Another inoculum consisted in Pisolithus sp. spores from a site with ultramafic soils in New Caledonia. Inoculation with AM and ECM fungi from Bandalup Hill was beneficial to E. flocktoniae. Benefits consisted mainly of a reduction of Ni shoot translocation at the highest Ni soil level. At 1 mg/kg soil Ni, E. flocktoniae exhibited a certain degree of tolerance to Ni. A substantial increase in growth and nutrient uptake with Pisolithus sp. from Western Australia was also observed. The contribution of AM fungi from Bandalup Hill to E. flocktoniae, M. coronicarpa, H. verucosa, and Trifolium subterraneum (clover) was then examined in ultramafic soil from Bandalup Hill.Steaming of ultramafic soil increased the availability and plant uptake of P. Consequently, uninoculated seedlings grew better, and inoculation with AM fungi decreased the growth of native plant species but did not affect their shoot Ni concentration. The presence of AM fungi increased the concentration of P in shoots of native plants species. Inoculation had no effect on the growth and nutrient content of subterranean clover. As mining activities have the potential to reduce the infectivity of AM fungi in topsoils, the effect of disturbance and storage practices on the AM infectivity of ultramafic topsoils collected in summer or winter from Bandalup Hill was investigated. Disturbance consisted in passing topsoil through a 2mm seive and cutting roots into 1cm fragments. Disturbed topsoil was then stored at room temperature in pots that were either sealed from the atmosphere or left open, and pots were maintained at field capacity. E. flocktoniae seedlings were planted in undisturbed and disturbed topsoil just after topsoil collect and then after 3, 6 and 9 months of topsoil storage. AM fungi present in the topsoil collected in summer was less susceptible to initial disturbance than AM fungi present in topsoil collected during winter. Also, storage of topsoil in sealed pots watered to field capacity was more detrimental to its infectivity than storage of topsoil in dry conditions. Mycorrhizal fungi can contribute to the survival of some native plant species in the ultramafic soils of Bandalup Hill and they may represent another strategy to improve the success of Ni mine revegetation. However, such contribution may not be the unique avenue for native plants to survive in ultramafic soils of Bandalup Hill.
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Kelly, Rhys Owen. "Molecular and physiological aspects of arbuscular mycorrhizal symbiosis with near-isogenic white clover : a gene expression study." Thesis, University of South Wales, 2004. https://pure.southwales.ac.uk/en/studentthesis/molecular-and-physiological-aspects-of-arbuscular-mycorrhizal-symbiosis-with-nearisogenic-white-clover-a-gene-expression-study(d43e48e0-fee7-44d0-8c9f-5d690fe185b2).html.
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White clover (Trifolium repens L.) is an important component of low input pasture systems and can form effective associations with both nitrogen-fixing Rhizobium and phosphate-scavenging arbuscular mycorrhizal fungi (AMF). Understanding the genetic control of plant-AM interactions will allow clover breeders to develop genetic markers for selection of phenotypes favourable to AM symbiosis. Clover is normally an out-breeding species. Near-isogenic lines (NILs) developed from inbred lines of clover are ideal candidates for genetic studies since important agronomic traits are fixed. Four closely-related NILs provided plant material with contrasting phenotypes when inoculated with AMF Glomus mosseae. Seed-grown and clonal plants of these closely-related NILs were used to study gene expression associated with AM colonization and functioning. In order to relate plant phenotype responses specifically to changes in phosphorus availability, and ultimately to gene expression, a nutrient flowing culture system was developed in which nutrient application was constant and could be controlled. The only consistent phenotypic response discovered was a decrease in root production in response to AMF colonisation. Differential display demonstrated differences in gene expression in both leaves and roots of clover with and without AMF. These genes were mainly down-regulated in AMF plants and three were identified from a range of NILs under varying P concentrations. More apparent differences in gene expression were found in roots than in leaves, and in low rather than high AMF colonising lines. In total, 45 sequences were identified and cloned; 30 from leaves and 15 from roots. Sixteen sequences had homology with known genes, including protochlorophyllide oxido reductase and leghaemoglobin. The majority corresponded to ESTs from model legumes and from studies such as colonisation with AMF or Rhizobium, and phosphate or nitrogen starvation experiments. Six sequences were not found on any database, indicating that these corresponded to undiscovered genes either expressed or suppressed in AM white clover.
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Asif, Mohammad. "Comparative study of production, infectivity, and effectiveness of arbuscular mycorrhizal fungi produced by soil-based and soil-less techniques." Thesis, [Campbelltown, N.S.W. : The Author], 1997. http://handle.uws.edu.au:8081/1959.7/510.
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The present study was firstly aimed at producing the AM fungal inocula by using soil-based and soil-less culture techniques, including the in-vitro axenic technique, and secondly to assess the infectivity and effectiveness of the inocula so produced in glasshouse and field conditions. Indigenous AM fungi from 5 different sites of New South Wales were successfully propagated and multiplied using the pot-culture and atomizing disc aeroponic culture techniques, and their infectivity was measured using the MPN bioassay method. The coarse and fine sand mix was proven to be very effective for the production of AM fungal inocula. The findings indicated that aeroponic culture technique is far superior to that of conventional pot-culture technique, and could possibly substitute the most commonly used pot-culture technique of AM fungal inoculum production. The ultra-sonic nebulizer technology could possibly be an alternative to conventional aeroponic systems for producing AM fungal isolates in commercial quantities. The introduction of the sheared-root inoculum of Glomus intraradices, produced by the ultra-sonic nebulizer technique, into agricultural soils can substantially reduce the intake of P-fertilizers as much as 50% of the recommended level. The study also indicated that soil phosphorus is a critical factor in limiting mycorrhizal colonization, possibly limiting mycorrhizal responses.The research suggests that various commercially produced single or 'cocktail' inocula may work on mycorrhiza dependent plants in soils where the indigenous AM flora is either not abundant and/or efficient. Furthermore, ecophysiology of the same AM species have different effects on plant growth.
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Lansing, Jennifer Lyn. "Comparing arbuscular and ectomycorrhizal fungal communities in seven North American forests and their response to nitrogen fertilization /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2003. http://uclibs.org/PID/11984.
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Thesis (Ph. D.)--University of California, Davis and San Diego State University, 2003.Includes bibliographical references (leaves 142-144). Also available via the World Wide Web. (Restricted to UC campuses).
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Cripps, Cathy Lynn. "Aspen mycorrhizae : ecology, syntheses and growth studies /." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-10312009-020206/.
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Bizabani, Christine. "Ericoid mycorrhizal fungi and potential for inoculation of commercial berry species (Vaccinium corymbosium L.)." Thesis, Rhodes University, 2011. http://hdl.handle.net/10962/d1016127.
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Ericaceous plants are the richest growth form of the fynbos vegetation of South Africa. The fynbos is characterized by highly leached acidic soils, low mineral nutrients and climatically it is a winter rainfall and dry summer region. Ericoid mycorrhizal fungi associate with Erica species enhancing their ability to access essential nutrients for survival under unfavourable growth conditions. The aim of this study was to select local Ericaceae plant species and to isolate, identify and characterize the ericoid endophytes and assess these isolates as potential inocula for commercial berry species. Two ericaceous plants Erica cerinthoides L. and Erica demmissa Klotzsch ex Benth. were identified from the Mountain Drive area of Grahamstown, Eastern Cape. Root staining was used to confirm the mycorrhizal status of both plants. Hyphal coils typical of ericoid association were observed within the epidermal cells of the hair roots under a light microscope. The endophytes were successfully isolated in pure culture on 2% malt extract agar (MEA) and modified Fontana medium. Cultural morphology and microscopy were used for initial identification. Two slow growing isolates were selected. These isolates were further subjected to molecular identification; extracted DNA was amplified using ITS1 and ITS4 fungal primers. The rDNA gene internal transcriber spacer (ITS) was then sequenced and analyzed by comparison to sequences in the GenBank. On the basis of percentage sequence identity Lachnum Retz. species and Cadophora Lagerb. & Melin species were identified as the ericoid endophytes of E. cerinthoides and E. demmissa respectively. The optimum growth parameters of the fungal isolates were determined in 2% MEA incubated at varying temperatures and pH. It was established that both species had optimum growth at 27⁰C and pH 5. The Ericaceae species are sometimes found in metal contaminated sites were ericoid fungi have been proved to alleviate toxicity of their host. The fungal isolates were grown in increasing concentration of Cu²⁺ and Zn²⁺ in 2% MEA. The growth of Lachnum species decreased with increasing Zn²⁺ ions above 2.7 mM while Cadophora species showed a change in morphology and also decreased in growth with increased ion concentration. However there were no significant differences recorded in the growth of Cadophora and Lachnum species on increasing Cu²⁺ concentration. Lachnum and Cadophora isolates were formulated into a semi solid inoculum and inoculated onto micropropagated Vaccinni corymbosum L. plantlets of 5 different varieties. Colonization was low for all varieties, Elliott and Brightwell varieties recorded the highest colonization of 35% and 31% respectively. Lachnum species infected roots showed potential ericoid structures while the Cadophora inoculated plantlets had hyphal coils within the cortical cells typical of ericoid mycorrhizas. Inoculation significantly enhanced the shoot growth of Brightwell and Elliott varieties. The Chandler variety inoculated with Lachnum species showed improved shoot dry weight. The Bluecrop and Elliott varieties inoculated with Cadophora and Lachnum accumulated more root biomass. All inoculated Bluecrop plantlets had an improved canopy growth index. Brightwell plantlets inoculated with Lachnum species also had an enhanced canopy growth index. The growth responses were variable within varieties and between varieties. Treatments with the Cadophora and Lachnum have shown potential in the promotion of growth of the Blueberry species. The findings indicate the need to conduct trials under conditions which simulate the commercial growth conditions so as explore the optimum potential of the isolates.
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Frey, Beat W. "Arbuscular mycorrhizas and N-cycling in agricultural plant-soil systems /." [S.l.] : [s.n.], 1993. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=10235.
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Hambleton, Sarah. "Mycorrhizas of the ericaceae, diversity and systematics of the mycobionts." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ34773.pdf.
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McGee, P. A. "Role of mycorrhizas in the regeneration of arid zone plants /." Title page, contents and summary only, 1987. http://web4.library.adelaide.edu.au/theses/09PH/09phm1448.pdf.
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See, Lee Su. "Some aspects of the biology of mycorrhizas of the Dipterocarpaceae." Thesis, University of Aberdeen, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334651.
Full textAbstract:
Little is known of the biology and importance of the ectomycorrhizal symbiosis in the Dipterocarpaceae. This project was undertaken: 1) to follow dynamics of mycorrhizal infection of dipterocarp seedlings at different sites in the forest, to characterise the major fungal associations involved; 2) to follow mycorrhizal infection of dipterocarp seedlings under laboratory conditions with different inoculum sources; 3) to determine whether dipterocarp ectomycorrhizas function in a manner similar to temperature ectomycorrhizas in the uptake of specific nutrients. Twenty-four different ectomycorrhizal types were described from roots of newly germinated seedlings, two to seven month-old seedlings and wildings of Shorea leprosula (Miq.), and approximately 20 year-old S. acuminata Dyer, S. dasyphylla Foxw., S. leprosula and S. parvifolia Dyer trees. Seventeen types were tentatively identified to family level. Vesicular-arbuscular mycorrhizas were not found. In the forest, some 14 day-old S. leprosula seedlings were already ectomycorrhizal but infection could be absent up to seven months after germination. The results implied that hyphal connections were important in early infection of seedlings in the vicinity of parent trees. Mycorrhizal infection of sequentially sampled two to seven month-old seedlings declined over the sampling period at two sites in Gombak, Selangor and one in Ulu Langat, Selangor. Five to six ectomycorrhizal types were dominant on seedlings at each site and a succession of types was observed on seedling roots. At final harvest, increased plant growth was significantly correlated with ectomycorrhizal infection only at one site in Gombak where infection by 'dominant' types exceeded 30%. Non-mycorrhizal seedlings of S. acuminata, S. leprosula, Hopea helferi and H. odorata were able to grow normally in sterile soil under non-competitive situations. Seedlings were able to form ectomycorrhizas even with inoculum present in grassland soils or with inoculum from different host species in the case of H. helferi. Increased phosphorus uptake by ectomycorrhizal seedlings of S. acuminata, S. leprosula and H. odorata was demonstrated.
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Sanders, Ian Robert. "Seasonality, specificity and selectivity of vesicular-arbuscular mycorrhizas in grasslands." Thesis, University of York, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.280447.
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Lehto, Tarja Helena. "Role of mycorrhizas in drought resistance of Sitka spruce seedlings." Thesis, University of Edinburgh, 1989. http://hdl.handle.net/1842/11045.
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Kim, Chang-Gi. "Effects on Scots pine (Pinus sylvestris L.) and its mycorrhizas." Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.395165.
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Sancayaningsih, Retno Peni. "Studies of vesicular-arbuscular mycorrhiza in Wanagama I Forest Research Center, Yogyakarta, Indonesia." Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/30315.
Full textAbstract:
Three studies were conducted on VA mycorrhiza in Wanagama Forest Research Center, Yogyakarta, Indonesia. The first was on VA mycorrhizal status of four forest species (Acacia mangium, Acacia holosericea, Tectona grandis, and Swietenia macrophylla) plantations and nurseries of Acacia mangium and Tectona grandis. Samples from the field were only taken during the dry season, June 1988. These four six-year old forestry species were mycorrhizal. Nursery plants had higher VAM colonization than the plantation roots and both Acacia species have higher percent colonization than the other two species. Available phosphorus in calcareous soils is low and seems not to be a major contribution to the variation of VAM colonization. Potassium and sodium were more important in this case even though their role could not be determined in this study.
The second study was conducted to determine VAM fungal species associated with the plant species. There were 16 different spore types belonging to the genera Glomus, (the most common found), Sclerocystis, Scutellispora, and probably Acaulospora. Type of inoculum and host compatibility were suggested as important factors in the success of pot culture study.
The third study was carried out in a growth chamber to determine Acacia spp. response to single VAM fungal species and mixed species inoculum. Single species inoculum in both Acacia was observed to improve biomass and plant growth better than the mixed inoculum. Acacia mangium performed better with Glomus versiforme than did A. holosericea. Host compatibility, effectiveness of VAM spore inoculant, infectivity and environmental factors have major effects on plant growth responses.
Study of tropical VAM requires further basic research, including taxonomy. Experimental procedures such as pot culture technique, type of inoculum, growth media and host plant specificity along with evaluation of appropriate soil chemical analysis also requirefurther elaboration. These types of studies are needed to understand the relationship between VAM and the environment and in the application studies in agriculture and forestry. This information is especially important in tropical countries, where little research results and limited resources, such as for fertilizers, are available.Land and Food Systems, Faculty of
Graduate
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Sims, Karen. "Growth physiology and systematics of some S.E.Asian ectomycorrhizal fungi, with additional reference to isozyme interpretations." Thesis, University of Kent, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296723.
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Wong, Ching Chi. "The role of mycorrhizae associated with vetiveria zizaniodes and cyperus polystachyos in the remediation of metal (lead and zinc) contaminated soils." HKBU Institutional Repository, 2003. http://repository.hkbu.edu.hk/etd_ra/414.
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Baon, John Bako. "Role of mycorrhizas in the assessment of phosphorus efficiency in cereals." Title page, contents and summary only, 1994. http://web4.library.adelaide.edu.au/theses/09PH/09phb221.pdf.
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McGonigle, T. P. "Vesicular-arbuscular mycorrhizas and plant performance in a semi-natural grassland." Thesis, University of York, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379456.
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Asif, Mohammad. "Comparative study of production, infectivity, and effectiveness of arbuscular mycorrhizal fungi produced by soil-based and soil-less techniques /." [Campbelltown, N.S.W. : The Author], 1997. http://library.uws.edu.au/adt-NUWS/public/adt-NUWS20030716.094919/index.html.
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Kasiamdari, Rina Sri. "Interactions between arbuscular mycorrhizal fungi and other root-infecting fungi." Title page, contents and abstract only, 2001. http://web4.library.adelaide.edu.au/theses/09PH/09phk1887.pdf.
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Curland, Rebecca D. "The effects of plant invasion on arbuscular mycorrhizal fungi : a review of how these community dynamics are studied /." Connect to online version, 2009. http://minds.wisconsin.edu/handle/1793/45114.
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Roth, Aaron Lyle. "Mycorrhizae of outplanted conifer seedlings on eastern Vancouver Island." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/29864.
Full textAbstract:
Mycorrhizal colonization and types of mycorrhizae that formed on container-grown Douglas-fir, western hemlock, and western red cedar seedlings were determined in a nursery near Nanaimo, B.C. and under a range of field conditions on eastern Vancouver Island. Methods included a root clearing,
bleaching, and staining procedure that allowed for accurate estimates of percentage colonization and some advantages in mycorrhiza characterization. The percentage of Douglas-fir and western hemlock short roots colonized by ectomycorrhizal fungi in the nursery was highly variable but over 99 percent of the mycorrhizae were formed by Thelephora terrestris. After one field season mycorrhizal colonization levels were between 72 and 93 percent on the new roots formed. The most difficult to regenerate site had the lowest percentage colonization and number of ectomycorrhizal types. T. terrestris mycorrhizae still had the highest relative abundance followed by Rhizopogon vinicolor (on Douglas-fir only), Cenococcum geophilum, Mycelium radicus atrovirens, Tujber-like, Sndogone-like, and 38 minor types of ectomycorrhizae. Some types of ectomycorrhizae were only present or common on specific sites. This included a type that formed spore-like structures on the mantle cystidia and a type that produced red-brown hyphal exudates. Douglas-fir seedlings artificially inoculated with R. vinicolor in an Oregon nursery were taller than control seedlings when outplanted but no height or weight difference was found after one field season. The 17 types of mycorrhizae that formed on the control seedlings were dominated in relative abundance by a type that was morphologically identical to that formed on the seedlings that were artificially inoculated with R. vinicolor. Western red cedar did not form mycorrhizae in the nursery but formed low levels of vesicular-arbuscular mycorrhizae in the field that included both fine and coarse endophytes.Land and Food Systems, Faculty of
Graduate
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Hollick, Penelope Sarah. "Mycorrhizal specificity in endemic Western Australian terrestrial orchids (tribe Diurideae): implications for conservation." Thesis, Hollick, Penelope Sarah (2004) Mycorrhizal specificity in endemic Western Australian terrestrial orchids (tribe Diurideae): implications for conservation. PhD thesis, Murdoch University, 2004. https://researchrepository.murdoch.edu.au/id/eprint/103/.
Full textAbstract:
The specificity of fungal isolates from endemic Western Australian orchid species and hybrids in the tribe Diurideae was investigated using symbiotic seed germination and analysis of the fungal DNA by amplified fragment length polymorphism (AFLP). The distribution of the fungal isolates in the field was also assessed using two different seed baiting techniques. The information from these investigations is essential for developing protocols for reintroduction and translocation of orchid species.
Two groups of orchids in the tribe Diurideae were studied. Firstly, a number of Caladenia species, their natural hybrids and close relatives from the southwest of Western Australia were selected because orchid species from the genus Caladenia are considered to have among the most specific mycorrhizal relationships known in the orchid family ? an ideal situation for the investigation of mycorrhizal specificity. Secondly, species of Drakaea and close relatives, from the southwest of Western Australia and elsewhere in Australia, which are never common in nature and occur in highly specialised habitats, were selected to investigate the influence of habitat on specificity.
Seed from the common species Caladenia arenicola germinated on fungal isolates from adult plants of both C. arenicola and its rare and endangered relative C. huegelii, while seed from C. huegelii only germinated on its own fungal isolates. The AFLP analysis grouped the fungal isolates into three categories: nonefficaceous fungi, C. huegelii type fungi, and C. arenicola type fungi. The group of C. huegelii type fungi included some fungal isolates from C. arenicola. An analysis of the AFLP fingerprints of C. arenicola fungal isolates from different collection locations showed that some, but not all, populations were genetically distinct, and that one population in particular was very variable.
Despite being thought to have very specific mycorrhizal relationships, Caladenia species hybridise frequently and prolifically in nature, often forming self-perpetuating hybrid lineages. Five natural hybrids within Caladenia and its closest relatives were investigated. Symbiotic cross-germination studies of parental and hybrid seed on fungi from the species and the naturally occurring hybrids were compared with AFLP analyses of the fungal isolates to answer the question of which fungi the hybrids use. The germination study found that, while hybrid seeds can utilise the fungi from either parental species under laboratory conditions, it is likely that the natural hybrids in situ utilise the fungus of only one parental species. Supporting these observations, the AFLP analyses indicated that while the parental species always possessed genetically distinct fungal strains, the hybrids may share the mycorrhizal fungus of one parental species or possess a genetically distinct fungal strain which is more closely related to the fungus of one parental species than the other.
The work on Caladenia hybrids revealed that C. falcata has a broadly compatible fungus that germinated seeds of C. falcata, the hybrid C. falcata x longicauda, and species with different degrees of taxonomic affinity to C. falcata. In general, germination was greater from species that were more closely related to C. falcata: seeds from Caladenia species generally germinated well on most C. falcata isolates; species from same subtribe (Caladeniinae) germinated well to the stage of trichome development on only some of the fungal isolates and rarely developed further; and seeds from species from different subtribes (Diuridinae, Prasophyllinae, Thelymitrinae) or tribes (Orchideae, Cranichideae) either germinated well to the stage of trichome development but did not develop further, or did not germinate at all. The AFLP analysis of the fungal isolates revealed that the fungi from each location were genetically distinct.
In situ seed baiting was used to study the introduction, growth and persistence of orchid mycorrhizal fungi. A mycorrhizal fungus from Caladenia arenicola was introduced to sites within an area from which the orchid and fungus were absent, adjacent to a natural population of C. arenicola. In the first growing season, the fungus grew up to 50 cm from its introduction point, usually persisted over the summer drought into the second season and even into the third season, stimulating germination and growth to tuber formation of the seeds in the baits. Watering the inoculated areas significantly increased seed germination.
Mycorrhizal relationships in Drakaeinae were less specific than in Caladeniinae. A study of the species Spiculaea ciliata revealed that this species, when germinated symbiotically, develops very rapidly and has photosynthetic protocorms, unlike all other members of the Drakaeinae. An AFLP analysis of the fungal isolates of this species grouped the isolates according to whether they had been isolated from adult plants or reisolated from protocorms produced in vitro. Isolates were genetically distinct when compared before germination and after reisolation. A cross-species symbiotic germination study of seeds of three Drakaea species and one Paracaleana species against fungal isolates from the same species and several other Drakaeinae species revealed lower specificity in this group than previously thought. A number of fungal isolates from Drakaea and Paracaleana species germinated two or more seed types, while all seed types germinated on fungal isolates from other species and the seed of Drakaea thynniphila germinated to some extent on every fungal isolate tested. An AFLP analysis of the Drakaeinae fungal isolates supported this information, revealing little genetic differentiation between the fungi of different orchid species.
An ex situ seed baiting technique was used to examine the role of mycorrhizal fungi in microniche specialisation in the narrow endemic Drakaea. Soil samples from within and outside two Drakaea populations were tested for germination of the relevant seed types. In both cases, germination was significantly higher on soil samples from within than outside the populations, suggesting that the relevant mycorrhizal fungi may be restricted to the same microniches as the Drakaea species. The presence of similar fungi at distant, disjunct locations may be related to the extreme age and geological stability of the Western Australian landscape.
The information from these investigations is essential for developing protocols for reintroduction and translocation of orchid species. It appears that the mycorrhizal relationships in these groups of orchids are not as specific as was previously thought. For reintroduction work, a broad sampling strategy is necessary, as it cannot be assumed that the same orchid species has the same fungus at different locations. A broadly compatible fungus may be of considerable utility in conservation work, such as in situations where a specific fungus appears to have poor saprophytic competence or where soil conditions have been altered. Seed baiting studies provide additional data on fungal distribution in situ. In general, molecular data do not provide information about efficacy or fungal distribution, so research programs that combine symbiotic germination studies with seed baiting investigations and genetic analyses of the fungi will provide the maximum benefit for designing more effective conservation programs.
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Hollick, Penelope Sarah. "Mycorrhizal specificity in endemic Western Australian terrestrial orchids (tribe Diurideae) : implications for conservation /." Hollick, Penelope Sarah (2004) Mycorrhizal specificity in endemic Western Australian terrestrial orchids (tribe Diurideae): implications for conservation. PhD thesis, Murdoch University, 2004. http://researchrepository.murdoch.edu.au/103/.
Full textAbstract:
The specificity of fungal isolates from endemic Western Australian orchid species and hybrids in the tribe Diurideae was investigated using symbiotic seed germination and analysis of the fungal DNA by amplified fragment length polymorphism (AFLP). The distribution of the fungal isolates in the field was also assessed using two different seed baiting techniques. The information from these investigations is essential for developing protocols for reintroduction and translocation of orchid species.
Two groups of orchids in the tribe Diurideae were studied. Firstly, a number of Caladenia species, their natural hybrids and close relatives from the southwest of Western Australia were selected because orchid species from the genus Caladenia are considered to have among the most specific mycorrhizal relationships known in the orchid family ? an ideal situation for the investigation of mycorrhizal specificity. Secondly, species of Drakaea and close relatives, from the southwest of Western Australia and elsewhere in Australia, which are never common in nature and occur in highly specialised habitats, were selected to investigate the influence of habitat on specificity.
Seed from the common species Caladenia arenicola germinated on fungal isolates from adult plants of both C. arenicola and its rare and endangered relative C. huegelii, while seed from C. huegelii only germinated on its own fungal isolates. The AFLP analysis grouped the fungal isolates into three categories: nonefficaceous fungi, C. huegelii type fungi, and C. arenicola type fungi. The group of C. huegelii type fungi included some fungal isolates from C. arenicola. An analysis of the AFLP fingerprints of C. arenicola fungal isolates from different collection locations showed that some, but not all, populations were genetically distinct, and that one population in particular was very variable.
Despite being thought to have very specific mycorrhizal relationships, Caladenia species hybridise frequently and prolifically in nature, often forming self-perpetuating hybrid lineages. Five natural hybrids within Caladenia and its closest relatives were investigated. Symbiotic cross-germination studies of parental and hybrid seed on fungi from the species and the naturally occurring hybrids were compared with AFLP analyses of the fungal isolates to answer the question of which fungi the hybrids use. The germination study found that, while hybrid seeds can utilise the fungi from either parental species under laboratory conditions, it is likely that the natural hybrids in situ utilise the fungus of only one parental species. Supporting these observations, the AFLP analyses indicated that while the parental species always possessed genetically distinct fungal strains, the hybrids may share the mycorrhizal fungus of one parental species or possess a genetically distinct fungal strain which is more closely related to the fungus of one parental species than the other.
The work on Caladenia hybrids revealed that C. falcata has a broadly compatible fungus that germinated seeds of C. falcata, the hybrid C. falcata x longicauda, and species with different degrees of taxonomic affinity to C. falcata. In general, germination was greater from species that were more closely related to C. falcata: seeds from Caladenia species generally germinated well on most C. falcata isolates; species from same subtribe (Caladeniinae) germinated well to the stage of trichome development on only some of the fungal isolates and rarely developed further; and seeds from species from different subtribes (Diuridinae, Prasophyllinae, Thelymitrinae) or tribes (Orchideae, Cranichideae) either germinated well to the stage of trichome development but did not develop further, or did not germinate at all. The AFLP analysis of the fungal isolates revealed that the fungi from each location were genetically distinct.
In situ seed baiting was used to study the introduction, growth and persistence of orchid mycorrhizal fungi. A mycorrhizal fungus from Caladenia arenicola was introduced to sites within an area from which the orchid and fungus were absent, adjacent to a natural population of C. arenicola. In the first growing season, the fungus grew up to 50 cm from its introduction point, usually persisted over the summer drought into the second season and even into the third season, stimulating germination and growth to tuber formation of the seeds in the baits. Watering the inoculated areas significantly increased seed germination.
Mycorrhizal relationships in Drakaeinae were less specific than in Caladeniinae. A study of the species Spiculaea ciliata revealed that this species, when germinated symbiotically, develops very rapidly and has photosynthetic protocorms, unlike all other members of the Drakaeinae. An AFLP analysis of the fungal isolates of this species grouped the isolates according to whether they had been isolated from adult plants or reisolated from protocorms produced in vitro. Isolates were genetically distinct when compared before germination and after reisolation. A cross-species symbiotic germination study of seeds of three Drakaea species and one Paracaleana species against fungal isolates from the same species and several other Drakaeinae species revealed lower specificity in this group than previously thought. A number of fungal isolates from Drakaea and Paracaleana species germinated two or more seed types, while all seed types germinated on fungal isolates from other species and the seed of Drakaea thynniphila germinated to some extent on every fungal isolate tested. An AFLP analysis of the Drakaeinae fungal isolates supported this information, revealing little genetic differentiation between the fungi of different orchid species.
An ex situ seed baiting technique was used to examine the role of mycorrhizal fungi in microniche specialisation in the narrow endemic Drakaea. Soil samples from within and outside two Drakaea populations were tested for germination of the relevant seed types. In both cases, germination was significantly higher on soil samples from within than outside the populations, suggesting that the relevant mycorrhizal fungi may be restricted to the same microniches as the Drakaea species. The presence of similar fungi at distant, disjunct locations may be related to the extreme age and geological stability of the Western Australian landscape.
The information from these investigations is essential for developing protocols for reintroduction and translocation of orchid species. It appears that the mycorrhizal relationships in these groups of orchids are not as specific as was previously thought. For reintroduction work, a broad sampling strategy is necessary, as it cannot be assumed that the same orchid species has the same fungus at different locations. A broadly compatible fungus may be of considerable utility in conservation work, such as in situations where a specific fungus appears to have poor saprophytic competence or where soil conditions have been altered. Seed baiting studies provide additional data on fungal distribution in situ. In general, molecular data do not provide information about efficacy or fungal distribution, so research programs that combine symbiotic germination studies with seed baiting investigations and genetic analyses of the fungi will provide the maximum benefit for designing more effective conservation programs.
34
HASSAN, ALI SIDAHMED MOHMED. "EFFECTS OF MYCORRHIZAL FUNGI ON GROWTH, NODULATION, AND NITROGEN FIXATION OF ALFALFA (MEDICAGO SATIVA L.) SELECTED FOR HIGH AND LOW NITROGENASE ACTIVITY." Diss., The University of Arizona, 1986. http://hdl.handle.net/10150/188188.
Full textAbstract:
Twelve F(,1) families of alfalfa (Medicago sativa L.) plants having different potential for nitrogenase activity, and the two parental populations were tested for response to mycorrhizal inoculation in a low-phosphate soil mixture in the greenhouse. The purpose of this study was to: (a) determine the effects of vesicular-arbuscular mycorrhizae on growth, nutrition and nodulation of these 14 populations, (b) determine if differences existed between the populations with regard to several morphological characteristics, and (c) determine if certain characteristics can be transmitted across generations. The 14 populations were evaluated under four treatments: control no Myorrhizae, no Rhizobium; Rhizobium alone; Mycorrhizae alone; and the combination of Mycorrhizae and Rhizobium. The growth parameters measured differed significantly among the treatments and among the 14 populations studied, and no significant interaction between the populations and the treatments were found. The dual Mycorrhizae and Rhizobium treatment significantly increased plant height at 30 days and 60 days after planting, leaf area per plant, and plant top-dry-weight at two harvest dates. Mycorrhizal inoculation, however, decreased specific-leaf-weight significantly. Nitrogen fixation parameters such as nodule mass score, fibrous root score, and nitrogenase activity were increased significantly by the dual inoculation of mycorrhizae and rhizobium. The 14 populations differed significantly in nodule mass score, fibrous root score, and nitrogenase activity. Mycorrhizal inoculation increased nitrogen fixation more than plant growth. Correlation coefficients indicated that increased Nitrogenase activity is positively correlated with increased nodule mass, increased fibrous root mass, greater top-dry-weight, and leaf area. A step wise multiple regression showed that 49% of the variation in nitrogenase activity can be explained by the variation due to nodule mass, fibrous root mass, top-dry-weight, and leaf area. Several morphological characters showed a heritable response. Plants selected for high nitrogenase activity and high top dry weight transmitted these characteristics to their progenies.
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Ndeinoma, Albertina. "Mycorrhiza re-establishment on post mined rehabilitated areas of the Brand se Baai Succulent Karoo vegetation /." Thesis, Link to the online version, 2006. http://hdl.handle.net/10019/1133.
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Sulistyowati, Emy. "Development of molecular probes to distinguish vesicular-arbuscular mycorrhizal fungi." Title page, Summary and Contents only, 1995. http://web4.library.adelaide.edu.au/theses/09A/09as949.pdf.
Full textAbstract:
Bibliography: leaves 71-79. Almost 80 percent of plant taxa develop vesicular-arbuscular mycorrhizae (VAM) which are symbiotic associations between plant roots and soil fungi. The fungi are biotropic-obligate symbionts. Identification of VAM fungi is currently based on spore characteristics. Molecular techniques provide tools for better and more accurate identification of species, as well as for the examination of genetic variability occuring between individual spores of a single species.
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Yallop, Adrian Roy. "Biotic interactions in salt marsh zonation with particular reference to abuscular mycorrhizas." Thesis, University of East Anglia, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251656.
Full textAbstract:
Salt marshes occupy a narrow intertidal zone where conditions change from marine to terrestrial. As a consequence they exhibit severe clines in salinity and soil saturation. The characteristic zonation of the vascular plant communities occupying these habitats is believed to develop as a result of differential tolerance and competitive abilities of the plants that comprise them. There are however few data on the structure of salt marsh communities relative to either elevation or tidal inundation. The consequences of soil saturation and salinity may also affect the distributions of soil microflora, including the occurrence and development of arbuscular mycorrhizal fungi. As AM development can result in enhanced plant performance, and may alter competitive interactions, any edaphic limitation in their development could influence plant community development. Detailed surveying, and the use of two objective methods of defining zonation, has allowed a full description of the plant community structure, relative to elevation, to be made. This identifies three distinct species groupings within the zonation, and has enabled the identification of competitive dominants within the zonational sequence. The occurrence of AM development within the salt marsh community has also been accurately determined for the first time. This represents the first survey of AM fungi in UK salt marshes since 1928, and identifies a distinct cline in the occurrence of these fungi relative to inundation. The effects of mycorrhizal development by AMF isolated from salt marsh sediments on the growth of 5 halophytes is ascertained. The results suggest salt marshes are environments where the usual benefits of AM development do not apply. This may explain the low levels of mycotrophy observed amongst halophytes.
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Eason, W. R. "The cycling of phosphorus from dying roots including the role of mycorrhizas." Thesis, University of Bristol, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379597.
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Cox, Filipa. "The mycorrhizas of Europe's pine forests in the context of nitrogen pollution." Thesis, Imperial College London, 2010. http://hdl.handle.net/10044/1/6329.
Full textAbstract:
Most trees in temperate and boreal ecosystems form obligate associations with ectomycorrhizal (ECM) fungi, but environmental change may alter ECM communities, potentially having major impacts on forest ecosystem functioning. Understanding the potential consequences of environmental change requires knowledge about current ECM fungal distributions, both to provide a baseline against which to measure changes in communities, and to establish the effects of current broad-scale environmental gradients on mycorrhizal biogeography. This study aims to assess the feasibility of a continental-scale survey of ECM fungal communities across a network of long-term forest monitoring plots, and provide insights into the community ecology of these important organisms. Using a spatially hierarchical sampling strategy and molecular identification of the fungi forming ECM root tips, the ECM fungal communities within 12 plots in the UK and Germany were characterised. In combination with measurements of a range of environmental variables at the 12 plots, the data indicate that nitrogen availability is a potentially important determinant of ECM fungal composition and richness across large spatial scales, but that other environmental variables may also act at large scales to influence ECM fungal communities. Evidence is also found to support a role of interspecific competition structuring ECM fungal communities within, but not across, plots, and a complex interplay between environmental gradients, co-occurrence patterns and phylogenetic relatedness is revealed. Within plots, microsatellite analysis indicates that pine roots from adjacent trees overlap, and do not have exclusive below-ground territories. Re-sampling plots, and reciprocal transplantation of pine seedlings between plots, indicates that pine mycorrhizas are stable both over time and on transplanted seedlings. This work increases our knowledge of the belowground ecology of ECM fungi, and highlights the value of identifying mycorrhizal abundance and distribution patterns - effects of global environmental change may already be significantly altering communities of this functionally critical group.
40
Sukarno, Nampiah. "Effects of selected fungicides on vesicular-arbuscular mycorrhizal symbiosis." Title page, contents and summary only, 1994. http://web4.library.adelaide.edu.au/theses/09PH/09phs948.pdf.
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Cooke, Margaret Anne. "Vesicular-arbuscular mycorrhizae and base cation fertilization in sugar maple (Acer saccharum marsh L.)." Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=39428.
Full textAbstract:
Under field conditions, vesicles were the most frequently observed mycorrhizal structures in sugar maple, while greenhouse grown seedlings formed more arbuscules. Seasonal fluctuations of vesicular-arbuscular mycorrhizae existed. Mycorrhizal associations formed within 30 days in the greenhouse. Arbuscules were usually formed from hyphal coils and occasionally from linear hyphae spreading from cell to cell. Degenerating arbuscules were not observed. The addition of basic cations increased the number of vesicles formed and decreased the overall infection rates and seedling growth. The uptake of calcium, magnesium, and nitrogen decreased, and potassium uptake increased as fertilization rates increased. Positive correlations existed between the incidence of arbuscules and plant growth and health and between the incidence of arbuscules and the uptake of calcium, magnesium, nitrogen and phosphorus, and with the uptake ratios and these elements with potassium. This suggests that vesicular-arbuscular mycorrhizae may in some way be regulating ionic balance in these seedlings.
42
Joubert, Angelique. "Investigation on selected biotic and abiotic factors in the maintenance of the "fairy circles" (barren patches) of southern Africa." Diss., Electronic thesis, 2008. http://upetd.up.ac.za/thesis/available/etd-01172008-125625/.
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Sommerville, David W. "Phosphorus fertilization : effects on asparagus yield, and soil microbial parameters." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=80876.
Full textAbstract:
Asparagus (Asparagus officinalis) is a perennial crop well suited to grow in Quebec. Despite high demand for this crop, asparagus production is declining because of asparagus root rot disease that is caused by Fusarium spp. Phosphorus is one of the most important nutrients for the production of healthy asparagus roots that may resist infection by Fusarium. The objective of this study was to determine the effects of phosphorus (P) applications on asparagus yield and soil microbial parameters. Plots receiving 0 to 200% of the P recommendation, based on the Centre de reference en agriculture et agroalimentaire du Quebec (CRAAQ) guidelines, did not differ significantly (p < 0.05) in first year yield or plant tissue concentrations. However, asparagus receiving no fertilizer had 2 to 3 times higher arbuscular mycorrhizal colonisation of roots than other treatments in May 2003. Fresh marketable yield was negatively correlated to Fusarium incidence (p = 0.0091 r = -0.51) suggesting that plants with higher yields are less susceptible to Fusarium symptoms and that producers should avoid over-harvesting low yielding plants to reduce Fusarium spread in the field. Soil microbial activity was not affected consistently by P fertilizers because of high variability in the field.
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Wilkinson, Melinda M. "Changes in growth and survival by three co-occurring grass species in response to mycorrhizae, fire, and drought." Thesis, University of Hawaii at Manoa, 2003. http://proquest.umi.com/pqdweb?index=0&did=765961171&SrchMode=2&sid=6&Fmt=2&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1209417332&clientId=23440.
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Ferrier, R. C. "Nutrient dynamics during death and decay of fine roots and mycorrhizas of spruce." Thesis, University of Aberdeen, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372618.
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Moyersoen, Bernard. "Co-occurence of ectomycorrhizas and arbuscular mycorrhizas in tropical rainforests : extent and significance." Thesis, University of York, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387578.
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Murphy, Phillip James. "Plant-fungal interactions during vesicular-arbuscular mycorrhiza development : a molecular approach." Title page, contents and abstract only, 1995. http://web4.library.adelaide.edu.au/theses/09PH/09phm9778.pdf.
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Bibliography: leaves 153-185. Vesicular-arbuscular (VA) mycorrhiza formation is a complex process which is under the genetic control of both plant and fungus. This project aims to develop a model infection system in Hordeum vulgare L. (barley) suitable for molecular analysis; to identify host plant genes differentially expressed during the early stages of the infection process; and to screen a mutant barley population for phenotypes which form abnormal mycorrhizas.
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Mukasa-Mugerwa, Thomas Tendo. "The role of arbuscular mycorrhizal fungi in the biotransformation of coal and application in dump rehabilitation." Thesis, Rhodes University, 2007. http://hdl.handle.net/10962/d1004059.
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Fundamental processes underpinning the biotransformation of coal by fungal biocatalysts have been intensively investigated, however, limited large-scale industrial applications using such systems have been reported. The un-anticipated sporadic growth of Cynodon dactylon on the surface of un-rehabilitated discard coal dumps has been noted and this was found to be coupled with the breakdown of coal into a humic soil-like material in the top 1.5 metres of the dumps. Extensive fungal growth was observed to be associated with the Cynodon dactylon root system and examination of plant roots indicated the presence of mycorrhizal fungi. Analysis of the Cynodon dactylon plant roots around which coal biotransformation was occurring confirmed the presence of arbuscular mycorrhizal colonisation with the species Glomus clarum, Paraglomus occultum, Gigaspora gigantea and Glomus mosseae identified to be associated with the plants. Further molecular characterisation of non-mycorrhizal rhizospheric fungi showed the presence of fungal species with coal-degrading capabilities that most likely played a role in the coal biotransformation observed. The discard coal dump environment was simulated in pot and column studies and coal biotransformation was reproduced, with this process enhanced by the addition of mycorrhizal and non-mycorrhizal rhizospheric fungal inocula to the environment. Mycorrhizal and non-mycorrhizal species in the inoculum were re-isolated from the simulated environment fulfilling a number of Koch’s postulates and indicating a causal role in the biotransformation of coal. An inversion of conventional mycorrhizal colonisation was demonstrated in this system with reduction in extraradicular presence and an increase in intracellular colonisation compared to soil controls. A descriptive model was formulated suggesting a two-part fungal system involving organic carbon and nutrient exchange between the plant, mycorrhizal fungi and non-mycorrhizal coal-degrading rhizospheric fungi ultimately resulting in the biotransformation of coal. The biotransformation observed was comparable to reports of “rock-eating fungi”. Results suggest that the biological degradation of coal in situ with the production of a soil-like substrate could provide a feasible method of discard coal dump rehabilitation as well as provide a humic-rich substrate that can be utilised in further industrial applications.
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Ghomsheh, Habib Nadian. "Effects of soil compaction on growth and P uptake by Trifolium subterraneum colonised by VAM fungi /." Title page, Contents and Summary only, 1997. http://web4.library.adelaide.edu.au/theses/09ASOP/09asopg427.pdf.
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PFEIFFER, CHARLES MICHAEL. "GROWTH AND NUTRITION OF MYCORRHIZAL GUAYULE IN SALINE SOILS (ENDOMYCORRHIZAE, GLOMUS INTRARADICES, SALINITY)." Diss., The University of Arizona, 1986. http://hdl.handle.net/10150/183780.
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Inoculation of Parthenium argentatum (guayule) with an endomycorrhizal fungus (Glomus intraradices) increased the growth of guayule in saline and non-saline soils low in available phosphorus. Addition of 100 ug/g of P as Ca(H2PO4)2 to soils low in available phosphorus was as efficient as G. intraradices in stimulating the growth of guayule. The concentrations and total plant accumulations of minerals within guayule shoots varied depending on growth of the plants and the minerals assayed. In most cases, the concentrations of Cu, Zn, Mn, Na and Cl increased in the shoot tissues of guayule grown in soils which contained added NaCl. Generally, addition of phosphorus to the soil resulted in decreased concentrations of Cu and Zn and increased concentrations of PO4 in guayule shoots. The total accumulations of minerals by guayule was directly influenced by the biomass of plants. Increased biomass of plants generally resulted in increased total accumulations of the minerals assayed. The influence of mycorrhizae on the accumulations of minerals by guayule grown in a saline soil was evaluated by comparing nonmycorrhizal plants with the same biomass and phosphorus nutrition as mycorrhizal plants. Mycorrhizae increased the concentrations and total plant accumulations of Zn and decreased the content of Cl within guayule shoots. Colonization of guayule roots by G. intraradices was not affected by addition of P to the soil. Addition of NaCl to the soil decreased the formation of arbuscules and vesicles within roots and increased the incidence in which no fungal structures were seen. The combination of P and NaCl added to soil had a synergistic effect on the mycorrhizae of guayule. Addition of both P and NaCl to soil reduced the occurrence of hyphae, arbuscules and vesicles within roots and decreased the overall infection of guayule roots by G. intraradices.