Electronic Theses and Dissertations

Date of Award

2013

Document Type

Dissertation

Degree Name

M.S. in Biological Science

Department

Biology

First Advisor

Jason D. Hoeksema

Second Advisor

Colin R. Jackson

Third Advisor

Stephen Brewer

Relational Format

dissertation/thesis

Abstract

Carbon dioxide in the atmosphere continues to increase, leading to an enhanced interest in the potential for ecosystems to sequester carbon. Soil could have a high potential to store carbon in these forests, but there is still a great deal to learn about how carbon storage in soils is influenced by ectomycorrhizal fungi. In this symbiosis, the plant host provides the vast majority of C for fungal growth. As a consequence, ECM fungi may provide one of the major pathways for C from trees to soils. Ectomycorrhizal fungal species produce extracellular enzymes that may degrade soil carbon and may differ in their ability to produce these extracellular enzymes to break down C in the soil. Additionally, tree genetics may control carbon storage in forests through influences on the functional diversity of mycorrhizal fungi, including enzyme activity. In this study, I examined the composition and functional traits of the ECM fungal community on different genotypes of Pinus palustris. I tested seven enzymes: β-1,4-xylosidase, β-1,4-glucosidase, cellobiohydrolase, phosphatase, β-N-acetylglucosaminidase, peroxidase and phenol oxidase to test my hypothesis that tree genetics directly influences particular ectomycorrhizal fungal enzyme activities and soil properties as well as indirectly controlling ectomycorrhizal fungal enzyme activities and soil properties by directly influencing the distribution of mycorrhizal fungal species. I found that ECM fungal community composition and peroxidase activity differed among tree families. Peroxidase activity differed among mycorrhizal fungal species. Amanita1 produced the highest amount of peroxidase activity, suggesting that Amanita1 may have the ability to obtain nutrients by degrading dead woody debris. N-acetylglucosaminidase activity differed among mycorrhizal fungal species, but not among tree families. Tomentella 1 produced the highest amount of β-N-acetylglucosaminidase activity, suggesting that Tomentella1 may have the ability to obtain nutrients by degrading saprobes. All other enzymes did not differ among mycorrhizal fungal species or tree families. Soil C, N and OM percentage did not vary among the ECM fungal community, tree family, or ECM fungal enzyme activities. Altogether, these results suggest that selection of plant genotypes could allow compositional management of microbial symbionts of trees, including the ECM fungal community, and possibly the traits of those microbial communities.

Included in

Biology Commons

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