This work consists of an introduction, six chapters dealing with various aspects of the response of mycorrhizal fungi to copper, and a brief conclusion. The first chapter examines the enzyme tyrosinase in several ectomycorrhizal fungi and shows that its activity is altered in these fungi in response to copper. Polyamines are also examined in this chapter, and it is shown that their levels are altered in some ectomycorrhizal fungi due to copper stress but not in others. The second chapter uses transmission electron microscopy to demonstrate that copper is bound to the hyphae of ectomycorrhizal fungi grown on solid media, but the location of the binding varies between fungal species. In vitro copper tolerances of a number of ectomycorrhizal species are compared in this chapter and differences in tolerance are evident between species and between different isolates of the same species. In the third chapter, four ectomycorrhizal fungi and one nonmycorrhizal fungus are evaluated for their ability to improve the growth of Japanese Red Pine under conditions of copper stress. Improvement of pine seedling growth is not correlated with in vitro copper tolerance of the fungus, but is related to the degree of compatibility between host and fungus. Despite differences in in vitro tolerance between three isolates of the same species, there are no differences in the effect of the isolates on the tree host under conditions of copper stress. Ectomycorrhizal fungi were also inoculated in pairs on pine seedlings and the competitive abilities of the fungi are compared under stressed and nonstressed conditions. The fourth chapter discusses the results of inoculation of pine with a nonhost fungus which stimulates dichotomous branching of the root system. The compound responsible for the branching is demonstrated to be indole-3-acetic acid (IAA), a plant growth hormone. The final two chapters deal with endomycorrhizal fungi. In the first of the two, inoculation of onion with an endomycorrhizal fungus demonstrates that the fungus probably plays no direct role in the response of the plant to heavy metals, based on biomass production, nutrient uptake, and photosynthetic rate. The last chapter demonstrates that the vascular plants found on abandoned mines in Virginia and North Carolina are well colonized by endomycorrhizal fungi; thus, an absence of these fungi is not a reason for the limited natural recolonization of the mine spoils. / Ph. D.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/54531 |
| Date | January 1989 |
| Creators | Gruhn, Christine Mae |
| Contributors | Biology, Miller, Orson K., Daniels, W. Lee, Palmer, John G., Paterson, Robert A., Rutherford, Charles L., Scheckler, Stephen E. |
| Publisher | Virginia Polytechnic Institute and State University |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | en_US |
| Detected Language | English |
| Type | Dissertation, Text |
| Format | vii, 149 leaves, application/pdf, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
| Relation | OCLC# 21329461 |
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