UBC Theses and Dissertations
The genus Leucosporidium in Southern British Columbia, an area of temperate climate Summerbell, Richard Charles
A search for members of the genus Leucospor idium (Ustilaginaceae) in and near southern British Columbia has yielded 147 isolates of L. scottii, and a single isolate of an undescribed species with apparent affinities in the genus. L. scottii was primarily found on decaying marine vegetation and driftwood, but isolates were also obtained from stream foam, snow, a decaying turnip root, bark mulch, and rain-derived stem flow over the trunk of a living tree. The species predominated in laboratory incubations of marine algal materials collected in the winter, spring, and late autumn. The majority of isolates obtained directly from natural substrates were also found during periods of cold seasonal conditions. It is suggested that low temperature is characteristic of L. scottii habitats. Locally-obtained L. scottii strains are all heterothallic, and are completely interfertile with mating test strains originating from the southern hemisphere. Morphological and known physiological and biochemical characters of the local strains are similar to those previously described for the species. However, mating studies of local isolates have revealed that the tetrapolar incompatibility system of L. scottii is distinguished by the possession of multiple alleles at the A locus. Similar modifications of the tetrapolar system are known in Tremella and other heterobasidiomycete genera, but have not previously been reported in species of the Leucosporidium-Rhodosporidium group. The strain thought to belong to an undescribed species of Leucosporidium was obtained from a sample of filamentous green algae growing in a vernal pond near a peat bog. The fungus is homothallic, and is morphologically and physiologically distinct from other Leucosporidium and Rhodosporidium species. Of the six known species of Leucosporidium, five (L. antarcticum, L. friqidum, L. gelidum, L. nivalis, and L. stokesii) were not found during the course of the present study. All five species are obligately psychrophilic and may not be able to remain established within the study area. However, a survey of local L. scottii isolates showed that 5 out of 147 isolates (3.4%) were obligately psychrophilic.
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