Doctoral Dissertations

Date of Award

12-2016

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Plants, Soils, and Insects

Major Professor

Kimberly D. Gwinn

Committee Members

Bonnie H. Ownley, Earnest C. Bernard, William E. Klingeman III, Nicole Labbe

Abstract

Sciadopitys verticillata produces white viscous resin that is unique among the conifers. This research investigated effects of resin on bacteria from different ecological niches and the chemical composition of the resin. Each bacterial species was evaluated separately for response to winter- and summer-collected resins. Exposure to winter-collected resin reduced numbers of colonies of Bacillus cereus, Erwinia amylovora, Agrobacterium tumefaciens, and Escherichia coli and increased numbers of Xanthomonascampestris, Pseudomonas fluorescens, and Pseudomonas syringae. Summer-collected resin affectedpopulation growth of two bacterial species; population counts of E. amylovora decreased and those of P. fluorescens increased. Selected strains of P. fluorescensare active against E. amylovora.

Nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR), gas chromatography mass spectrometry (GCMS), and pyrolysis GCMS were used to characterize chemical composition of resin of S. verticillata. Resin contained aldehydes, aromatics, olefins, alkoxy groups, ethers, alkyls, and carbonyls. Dimethyl sulfoxide extracts of resin containedα-pinene, tricyclene, and β-pinene (approximately 95% of total volatilesin GCMS analysis). In FTIR analysis, functional groups consistent with previous reportswere identified. Analysis supported the proposals that S. verticillata resin is chemically similar to Cupressaceous resins but no Pineaecous resins.

Principal component analysis, coupled with pyrolysis GCMS spectrometry data, was used to screen for differences among S. verticillata trees grown in eastern Tennessee. Resin from four of six different source trees had no obvious differences. Differences in pyrograms of resins from two genetically identical trees that received different amounts of light were functional groups normally associated with photosynthesis products; these products were low in abundance (1% or less) and low molecular weight. Principal component analysis was coupled with FTIR to evaluate differences between resin collected from S. verticillata and Frasier fir.Fraser fir was distinct from S. verticillata and did not contain the spectral signature of S. verticillata and other resins from plants believed to be related to S. verticillata.

This research is the most comprehensive study of resins collected from S. verticillata to date. Chemical basis of antimicrobial activity was not fully elucidated. Future research will address the role of chemical composition and resin concentration on antibacterial activity.

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