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A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of requirements for the degree of Master of Science. / Phytoremeditation of mine tailings provides the most cost-effective means of alleviating their pollutant effects. Research has shown that successful revegetation of mine tailings can be optimised by providing appropriate microbial symbionts for the plants. The aim of this study was to assess the arbuscular mycorrhizal (AM) status of trees currently being used for phytoremediation trials of mine tailings in the Welkom gold fields, and to determine the AM fungal diversity of these sites. The Acacia spp. analysed were growing on rehabilitated gold and uranium mine tailings which had undergone different rehabilitation regimes. Planted acacia trees which had been inoculated with crude AM fungal inocula were present on one mine tailing site as compared to the second mine tailing site on which the acacias were naturally colonisers and the site had been ameliorated with garden refuse. Root and slime samples were collected in early spring and half if each initial sample was used immediately for colonisation analysis and to identify AM fungi through molecular analysis of the small subunit rRNS gene sequences; the other half of each sample was used to produce trap cultures which were used later for colonisation and molecular analysis. Total AM fungal colonisation of initial samples for planted acacies was 19 % and for naturally colonising acacias was 66 %. The total AM fungal colonisation of trap culture samples for planted acacias increased to 32 % and for naturallhy colonising acacias it increased to 78 %. Spore counts of initial samples averaged 402 spores per 100 g-1 soil for planted acacias and 455 spores per 100 g-1 soil for naturally colonising acacias. For trap culture samples, spore counts decreased by approximately 50 %. The AM fungi identified fell within 8 genera, namely, Diversispora, Rhizophagus, Scutellospora, Claroideoglomus, Cetraspora, Sclerocystis, Glomus and Redecker. The study represents a first report utilising molecular biosystematics with AM fungal DNA from colonised roots as the template. The results will assist in making decisions about future AM fungal surveys and applying AM fungal inoculum in phytoremediation trials of mine waste sites. Key words: Phytoremediation, mine tailings, arbuscular mycorrhizal (AM) fungus, Acacia, molecular identification, SSU rRNA gene sequence

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No description available.

No description available.

No description available.

No description available.

Fungi associated with Engelmann spruce and subalpine fir were studied in a high altitude area of western Wyoming. Thirty permanent plots were established and their mean stand age determined. Three age classes were delineated: young (78 years), mature (127 years), and old-age (216 years). Stand and soil parameters including density, basal area, and soil pH, P, K, Ca, organic matter, and Mg concentrations were used to define similarities in stand characteristics. Sporocarps of higher basidiomycetes and ascomycetes were collected and identified, and ectomycorrhizal root tips sampled from each plot. Pure cultures of the basidiomycetes were routinely attempted. Mycorrhizal syntheses were subsequently attempted with both tree species using successful pure cultures. Thirty-nine species of higher fungi were collected during the study. Distribution of sporocarps throughout the age classes revealed a distinct fungal flora in each age class. Greatest density of species appeared in the mature stands. Non-mycorrhizal fungi were more abundant in the mature stand while mycorrhizal species were more abundant in the old-age stand. Mycorrhizal root counts increased from young to old-age stands. Low numbers of sporocarps and mycorrhizal rootlets were collected from the young stand. It seems evident from this study that a more diverse assemblage of higher fungi is present in mature and old-age forests and a progressive increase of fungal species from young to old-age stands supports the hypothesis that fungal succession is occurring in the study area. / Master of Science

Mycorrhizal synthesis studies revealed that allopatric populations of Suillus granulatus differ in host specificity. Tissue cultures of Suillus granulatus used were from Nepal, (associated with Pinus wallichiana), Korea (Pinus densiflora) and the U.S. (Pinus strobus). Mycorrhizal effectiveness was used to measure host specificity. Useful characters for measuring mycorrhizal effectiveness were determined by ANOVAs between the uninoculated controls and mycorrhizal treatments. In addition, those characters which were stable within one population were determined via ANOVA. Useful characters, as defined by these two tests were: shoot wet weight, total wet weight, percentage mycorrhizal short roots, shoot dry weight, total dry weight and Hartig net penetration. These characters were subsequently used to measure variation in mycorrhizal effectiveness among the allopatric populations of Suillus granulatus. Isolates associated with Pinus strobus were most effective with Pinus strobus and least effective with the other trees, whereas isolates from Pinus wallichiana and Pinus densiflora showed variable effectiveness with all three trees. Phenetic analyses used to determine how similarly the isolates responded with the hosts confirmed these results. We conclude that isolates associated with Pinus strobus are most specific for this host, whereas isolates from the other two trees are not host specific. These results are discussed and hypotheses put forward to explain them. / Master of Science