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      Endophytic fungi associated with pioneer plants growing on the Athabasca oil sands

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      Xiaohui_Bao_thesis.pdf (1.873Mb)
      Date
      2009-06-04
      Author
      Bao, Xiaohui
      Type
      Thesis
      Degree Level
      Masters
      Metadata
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      Abstract
      Fungal endophytes live inside plants without causing apparent symptoms of infection. All plant species surveyed thus far, including liverworts, mosses, seedless vascular plants, conifers, and angiosperms, harbor one or more endophytic fungi. Fungal endophytes can be divided into four groups including class 1, class 2, class 3 and class 4 endophytic fungi according to host range, colonization pattern, transmission, and ecological function. Class 2 fungal endophytes benefit their host by increasing environmental stress tolerance (i.e. water, temperature, salt) in a habitat-specific manner. In my study, class 2 fungal endophytes were studied from weedy plants growing in an environmentally stressed area: mine tailings from the Athabasca oil sands. This area is a vast hydrocarbon reserve in western Canada that supplies 10% of Canadian oil needs. Hydrocarbons are extracted from tar sands with hot water, alkali, and solvents. The tailing sands can later be remediated (by adding organic material and fertilizer) to establish new plant communities. Prior to remediation, tailing sands have extremely low content of organic carbon and available minerals, and are hydrophobic compared to unimpacted and remediated soils. Nevertheless, Taraxacum (dandelion) and Sonchus (sow-thistle) can colonize extracted tailing sands even prior to remediation. Preliminary results show that pioneer plants have similar fungal abundance as plants of unextracted treatments. Fungal endophytes were isolated from surface sterilized Taraxacum and Sonchus that had been growing upon unimpacted, remediated and extracted soil. Fungi isolated in this way included Alternaria, Tricoderma, Fusarium and an unidentified Perithecial Ascomycote. These endophytic fungi were used to inoculate tomato plants in a greenhouse trial to determine whether they confer stress tolerance to host plants, especially for drought and low mineral nutrition. Before exposing the tomato plants to environmental stresses, the specific endophytic fungal strains applied were successfully recovered from tomato plants originally inoculated with the same endophytic fungi. Although the other endophytic fungi turned out to be harmful to the tomato plants in the test, a Trichoderma spp. strain isolated from samples of extracted treatment appears to confer tolerance of tailing sands to the tomato plants. This Trichoderma spp. strain which we can call TSTh20-1 was molecularly identified as Trichoderma harzianum. Despite an identification to species, all strains of T. harzianum are not necessarily identical regarding strain-specific attributes. Using similar techniques described here, it is possible to isolate and potentially use beneficial class 2 endophytic fungal strains for the remediation process in the Athabasca oil sands or to assist plant growth in other high stress environments.
      Degree
      Master of Science (M.Sc.)
      Department
      Biology
      Program
      Biology
      Supervisor
      Kaminskyj, Susan
      Committee
      Johnstone, Jill; Germida, Jim; Chivers, Doug; Niyogi, Som
      Copyright Date
      June 2009
      URI
      http://hdl.handle.net/10388/etd-05132009-134050
      Subject
      Tailing Sands
      Trichoderma
      Endophytic Fungi
      Symbiosis
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      • Graduate Theses and Dissertations
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