Honors Theses
Date of Award
2011
Document Type
Undergraduate Thesis
Department
Biology
First Advisor
Jason Hoeksema
Relational Format
Dissertation/Thesis
Abstract
Ectomycorrhizal fungi (ECM) are abundant symbionts of trees in many dominant terrestrial ecosystems. Moreover, ECM communities are speciose and vary in composition over time and space. However, we still understand surprisingly little about variation in function of different ECM species, and thus the consequences of variation in ECM community composition. I studied variation in ECM community composition and enzymatic activities on the roots of loblolly pine (Pinus taeda) along a successional gradient from an old field to a second-growth mixed forest in northern Mississippi. I sought to determine not only whether ECM communities changed along the gradient, but also whether there were functional differences among the dominant ECM species as indicated by their enzymatic activities. Specifically, loblolly pine roots colonized by ECM were collected along two transects spanning a chronosequence where an abandoned old field is being colonized by loblolly pine, which is also a dominant member of the adjacent second-growth forest. I counted and separated roots by ECM morphotype, confirmed morphotype identities using molecular techniques, and tested representative ECM root tips from each sample for activities of four classes of degradative enzymes: phenol oxidase, peroxidase, betaglucosidase, and phosphatase. I found significant differences in ECM community composition and function (as indicated by enzyme activities) between the field and forest habitats along the gradient, and between pine age classes (adults versus seedlings) within the forest. Phenol oxidase, which contributes to lignin degradation, was significantly more active in ECM tissues from the forest than from the field, and peroxidase, also involved in lignin degradation, was significantly more active in samples from the field compared to the forest. Within the forest, ECM colonizing adult trees exhibited significantly higher phenol oxidase activity compared to those on seedlings. Activities of betaglucosidase and phosphatase did not vaiy along the gradient. These data suggest how the function of ECM, with respect to their effect on litter decomposition processes, may vary during the time course of key ecological processes such as secondary succession.
Recommended Citation
Brasher, Becky Anne, "Variation in Enzymatic Capabilities of Ectomycorrhizal Fungi along a Loblolly Pine Successional Gradient" (2011). Honors Theses. 2177.
https://egrove.olemiss.edu/hon_thesis/2177
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