Thesis (M.Sc.)--York University, 2005. Graduate Programme in Biology. / Typescript. Includes bibliographical references (leaves 79-101). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url%5Fver=Z39.88-2004&res%5Fdat=xri:pqdiss &rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR11880

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Thesis (MSc)--University of Stellenbosch, 2002. / ENGLISH ABSTRACT: Five new species of ophiostomatoid fungi, colon ising the infructescences of serotinous Protea species, have recently been discovered in South Africa. Prior to this, ophostomatoid fungi were thought to be restricted to the Northern Hemisphere. The discovery of these five species thus extensively expanded the known geographical range of these fungi, now also to include the Southern Hemisphere. Since this discovery, few studies have focused on the interesting ecology of this group, which is uniquely adapted for spore dispersal by arthropods. Studies focussed on ophiostomatoid fungi provide an unique opportunity to study inter-organism interactions between fungi, their host plants and the arthropods responsible for their spore dispersal. Very few similar studies have been undertaken, particularly in the Fynbos Biome, to which most of our economically important Protea species are confined. The current study provides insight into some ecological aspects of these complex interactions. The seasonal distribution of the ophiostomatoid fungi associated with the infructescences of members of the Proteaceae was investigated. Definite seasonal patterns were observed, with peak fungal colonisation occurring during the wetter winter months. While determining the host specificity of these fungi, a new Protea host for Ophiostoma splendens was identified, and a new species of Rhyncomeliola was discovered. All ophiostomatoid species native to Fynbos in the Stellenbosch region are exclusively associated with the infructescences of species in the plant genus Protea. By employing a multiplex Polymerase Chain Reaction (PCR), a set of group specific primers was developed for the identification of South African Ophiostoma and Gondwanamyces fungal DNA. This newly developed method was used to scan arthropods collected from the infructescences of P. repens for the presence of 0. splendens and G. proteae spores. By using these group-specific primers, three insects possibly responsible for long range dispersal of fungal spores were identified. Three further insect species, possibly contributing to the short-range dispersal of ophiostomatoid spores, were also implicated through this method. All arthropods associated with the fruiting structures of selected members of the Proteaceae were also investigated. A total of 62 pseudospecies (ca. 7500 individuals), belonging to 45 different arthropod families, were collected. Proteaceae species with larger fruiting structures housed more arthropod species and higher numbers of individuals than Proteaceae taxa with smaller fruiting structures. Some plant species housed similar arthropod communities, while others housed unique suites of arthropods. Seasonal patterns in arthropod numbers were observed, and it was found that, in most instances, arthropod numbers peaked during the autumn and winter months. Twenty-five fungal taxa were isolated from various Proteaceae arthropods, many of which are genera known to include Proteaceae pathogenic species. Ophiostomatoid fungi have a saprophytic relationship with their Protea hosts, and may deter some of these potentially harmful fungi from colon ising the infrutescences. Some fungi showed a high degree of specificity towards potential vectors, while others were found on a diverse range of arthropods. This study highlights the existence of complex inter-organismal interactions within the Fynbos Biome, a study area where the interactions between plants, fungi and insects have been grossly neglected. The few studies that have been conducted in this field have mostly focussed on a limited number of organisms, and no wide-scale attempts, such as presented here, have been published. It is important to obtain a holistic view in any ecological study that focuses on interactions between different suites of organisms. Ultimately this will aid in the development of better conservation strategies. This study thus provides a muchneeded start in studies on multi-organismal interactions in the Fynbos Biome. / AFRIKAANSE OPSOMMING: Vyf nuwe ophiostoma-agtige fungus spesies is onlangs in die vrug-liggame van Suid Afrikaanse Protea plante ontdek. Voor hierdie ontdekking, was die algemene opvatting dat ophiostoma-agtige fungi beperk is tot die Noordelike Halfrond. Die ontdekking van hierdie vyf spesies het dus die bekende geografiese verspreiding van hierdie tipe fungi vergroot om nou ook die Suidelike Halfrond in te sluit. Sederdien het min studies gefokus op die interesante ekologie van hierdie groep, wat aangepas is vir spoorverspreiding deur geleedpotiges. Studies wat fokus op die ophiostoma-agtige fungi voorsien 'n unieke geleentheid om die inter-organismiese-interaksies tussen fungi, hul gasheer plante en die geleedpotiges wat hul spore versprei, te bestudeer. Baie min soortgelyke studies is al voorheen in die Fynbos Bioom, waar die meeste van ons ekonomies-belangrike Protea spesies voorkom, onderneem. Die huidige studie verleen meer inligting oor sommige ekologiese aspekte van hierdie komplekse interaksies. Seisoenale verspreidingspatrone van ophiostoma-agtige fungi geassosieer met die vrug-liggame van lede van die Proteaceae, is ondersoek. Daar is defnitiewe seisoenale patrone in die aanwesigheid van fungi gevind, met 'n piek in fungi kolonisasie-getalle gedurende die vogtiger wintermaande. 'n Nuwe Protea gasheer vir Ophiostoma splendens en 'n nuwe fungus spesie (Rhyncomeliola sp.), is ontdek. Alle Fynbos ophiostoma-agtige spesies in die Stellenbosch area, is beperk tot Protea spesies. 'n Multipleks Polimerase Ketting Reaksie is ontwikkel om die spesifieke DNS van ophiostoma-agtige fungi te herken. Hierdie metode is gebruik om te toets vir die aanwesigheid van spore van hierdie fungi op die liggame van geleedpotiges (geassosieerd met P. repens). Hierdeur is drie insekte wat waarskynlik verantwoordelik is vir die langafstand verspreiding van spore geidentifiseer. Drie verdere insekte wat moontlik verantwoordelik is vir die kortafstand verspreiding van ophiostoma-agtige fungi is ook aangewys. Alle geleedpotiges geassosieer met die vrugstrukture van geselekteerde lede van die Proteaceae is ondersoek. 'n Totaal van 62 pseudo-spesies (omtrent 7500 individue), wat tot 45 families behoort, is versamel. Proteaceae spesies met groter vrugstrukture het meer geleedpotige spesies en individue gehuisves as taksa met kleiner vrugstrukture. Sommige plant spesies het soortgelyke geleedpotige gemeenskappe gehuisves, terwyl unieke groepe geleedpotiges in ander plante voorgekom het. Alhoewel die geleedpotiges seisonale variasies in getalle geopenbaar het, het die meeste groepe 'n piek in getalle getoon gedurende die herfs- en wintermaande. Vyf-en-twintig fungi taksa is geïsoleer vanaf verskeie Proteaceae geleedpotiges. Sommige van hierdie is genera wat Proteaceae patogeniese spesies insluit. Sommige fungi het 'n hoë graad van spesifisiteit teenoor potensiële vektore getoon, terwyl ander weer algemeen op verskeie geleedpotige spesies gevind is. Hierdie studie dui op die bestaan van komplekse inter-organismiese-interaksies in die Fynbos Bioom, in 'n area waar die studie van interaksies tussen plante, fungi en insekte nog baie min aandag geniet het. Die beperkte aantal studies wat tot dusver in hierdie veld onderneem is, fokus gewoonlik slegs op 'n paar organismes. Geen grootskaalse studies, soos die een hier voorgelê, is al gepubliseer nie. In enige ekologiese studie wat fokus op interaksies tussen verskeie organismes, is dit belangrik om 'n holistiese siening te probeer verkry. Uiteindelik sal dit bydra tot die ontwikkeling van beter bewarings-strategië. Hierdie studie verleen dus 'n noodsaaklike begin tot studies op multiorganismiese- interaksies.

Thesis (doctoral)--Swedish University of Agricultural Sciences, 2002. / Thesis documentation sheet inserted. Appendix reprints three manuscripts and one published paper, three of which are co-authored with others. Includes bibliographical references. Also issued electronically via World Wide Web in PDF format; PDF version lacks abstract, ack., and appendix. One ill. in PDF version is in col.

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).

The main project was an assessment of the effect that colonization by five different Vesicular-arbuscular mycorrhiza (VAM) cultures have on the growth of the indigenous-grasses Themeda triandra and Trachypogon spicatus, when grown on coalmine topsoil. With unamended topsoil, VAM showed the ability to significantly increase the growth of the grasses compared to non-VAM control plants. The amount of effect varied with the VAM inoculum culture type, with a VAM culture originally from the Cape Flats being the most effective. In a second trial, soil fertilized with nitrogen, potassium and low concentrations of phosphate (P) was used. Again VAM displayed the ability to improve grass plant growth. The increase in P caused the Large spore inoculum to become the most effective. This indicated that different VAM cultures are inhibited to different degrees by an increase in phosphate fertilization. The low level of VAM infection, in both trials, seemed to preclude most of the VAM associated nutrient uptake control. Varying reports have been published on the effect of fertilization on VAM infection and colonization. In an attempt to further elucidate the role of fertilizer in VAM inhibition, rhizosphere soil from a long term fertility trial near Witbank, S.A. was sampled. Amcoal environmental services fertilized forty-two plots with varying concentrations of nitrogen, potassium, phosphate and lime to assess the growth of a variety of grasses. The trial had been maintained for ten years before sampling was completed for this project. Samples from each plot were taken from the rhizosphere soil of the most prominent grass (Digitaria eriantha). VAM spores were extracted from all the samples and five different types of spores were identified and counted for each sample. By comparing spore counts from each plot, the effect that the fertilizer regime had on the VAM on that plot could be assessed. Variation in the concentrations of nitrogen (N) and potassium had no significant effect on VAM colonization. Very low concentrations of N could not be assessed as all plots had been initially top dressed with nitrogen fertilizer. Phosphate (P) fertilizer concentration had a marked effect on spore concentrations. There was a significant increase in spore concentration as P levels were increased from zero P fertilization to 80kgs P/ha. Further increase in P to ≥ 60kgs P/ha resulted in a significant decrease in spore concentrations. From this it would appear that a low level of soil P is needed to give maximum VAM colonization and further increase in soil P causes VAM inhibition. Lime ameliorated the VAM inhibition caused by high concentrations of P. Increase in P caused spore concentrations of low abundance propagules (LAP) too decreased more rapidly than high abundance propagules (HAP). In high P soils VAM with LAP would eventually be eliminated from the system resulting in a decrease in VAM diversity. A project was attempted to use the recently developed Randomly Amplified Polymorphic DNA in conjunction with the Polymerase Chain Reaction (RAPD PCR) techniques to identify different VAM families. The technique causes the amplification of segments of DNA which can be visualized by gel electrophoresis and staining. Band patterns formed can be related to the VAM of origin and hence used in identification of that VAM. An attempt was made to amplify DNA from a single spore in this manner which would, in conjunction with morphological observations, make identification of VAM easier and more accurate. Problems with either releasing the DNA from the spores, or substances in the spore inhibiting the PCR reaction made obtaining band patterns difficult. After many PCR attempts, varying extraction methods and PCR conditions, no repeatable results could be obtained and work on this project was discontinued. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1997.

Thesis (MScBosb)--University of Stellenbosch, 2007. / Bibliography. Also available via the Internet.

Thesis (Ph. D.)--University of Hawaii at Manoa, 2003. / Includes bibliographical references.

Specific questions regarding the community structure of VAmycorrhizal fungi and the population biology of an ectomycorrhizal addressed. The Basidiomycete, distributional Suillus granulatus, were ecology of VAM fungal communities with grasses was studied across a climatic gradient in the hyper-arid central Namib dune field. VAM fungal communities were primarily structured by substrate stability and moisture availability. Five VAM species were found throughout the study area and were not host specific. Percent mycorrhizal colonization was correlated with moisture availability, whereas spore abundance was correlated with substrate stability. Moisture availability was the key factor influencing VAM fungal phenology: growth, assessed as increased colonization of roots, continued as long as moisture was available, and spore production occurred in response to declining moisture availability. While abiotic factors determine community structure of VAM fungi in the Namib dune field, preliminary studies suggest that the phytobiont mediates fungal response to these abiotic factors. Genetic analyses of S. granulatus single spore isolates using RAPD markers showed that a post-meiotic mitosis in the basidium produces heterokaryotic spores. Secondary homothallism provides an effective means for long distance dispersal, and may account for the broad geographic range of this ectomycorrhizal fungus. Secondary homothallism contributed to the failure of somatic incompatibility tests to delineate the spatial distribution of individuals in a natural population of s. granulatus. Analysis of genetic relatedness using RAPD markers demonstrated conclusively that somatically compatible individuals were not necessarily genetically identical. I concluded that RAPD marker analysis provides a more effective means for determining clonal distribution in ectomycorrhizal populations, than does somatic incompatibility testing. / Ph. D.

Thesis (Ph. D.)--Institute of Paper Chemistry, 1984. / Includes bibliographical references (p. 54-56).