Analysis of lichens under environmental stress using Pyrolysis-GC-MS and Pyrolysis-GC-FID

MacGillivray, Tanya Frances (1999) Analysis of lichens under environmental stress using Pyrolysis-GC-MS and Pyrolysis-GC-FID. Masters thesis, Memorial University of Newfoundland.

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Abstract

Plants often react to various kinds of stress by changes in their organic composition as the result of defense or stress induced metabolism. This project investigated lichens as stress monitors, searching for changes in their chemistry under various environmental conditions. Qualitative analysis was carried out using Pyrolysis-Gas-Chromatography-Mass-Spectrometry following a micro-scale acetone extraction of dried and ground lichen samples. Only the newest growth of lichen was used. Semiquantitative analysis was carried out using Pyrolysis-Gas-Chromatography with a Flame Ionization Detector. -- Cladina mitis and Cladina rangiferina exposed to conditions of visible and/or ultraviolet light were received from Ontario. Bryoria trichodes and Usnea dasypoga were collected from sites of various ozone levels in New Brunswick. Alectoria sarmentosa was collected from sites of varying sulfur dioxide exposure in Newfoundland. Changes in the unique lichen phenolics and fatty acids were detected. Results suggest that unsaturated fatty acids may be useful indicators of ultraviolet, ozone and possibly sulfur dioxide stress. It seems some lichen phenolics such as salazinic acid, alectoronic acid and alectosarmentin, as well as possibly usnic acid and atranorin, may be used to detect these stresses and may be involved in defensive biochemical responses. Future work should focus on verifying which of these changes are specific to a given stress.

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