Metabolic differentiation in the lichen Cladonia portentosa from different wet nitrogen deposition regimes’

The deposition of atmospheric nitrogen is now recognized as a major driver of<br/>biodiversity changes at mid to high latitudes. It has previously been shown that<br/>regional variations in wet nitrogen deposition in the British Isles are reflected in<br/>broad targeted chemical parameters in the common heathland lichen Cladonia<br/>portentosa. A more detail analysis of alterations in the metabolic pathways in<br/>Cladonia portentosa collected from different locations within the UK was<br/>undertaken by applying the environmental metabolomics approach. Fourier<br/>transform infrared spectroscopy (FTIR) and liquid chromatography mass<br/>spectrometry (LC-MS) were applied in combination with principal component<br/>analysis (PCA) and partial least squares regression analysis (PLSR). The latter<br/>statistical method was used to correlate measured variables with modelled<br/>atmospheric data including wet nitrogen deposition, nitrogen concentration and precipitation. While FTIR in combination with PCA and PLSR revealed signatures of broad metabolic classes, LC-MS in combination with PCA and PLSR allowed the identification of betaine lipids (BL) as potential biomarkers of nitrogen enrichment.<br/>A compound tentatively identified as monoacylglycerol-(N,N,N trimethyl)-<br/>homoserine (MGTS) showed the strongest positive relation to increasing wet<br/>nitrogen deposition regimes and consequent phosphorus deficiency. In contrast, the structurally related phosphatidylcholine containing a C18:2 ester showed the opposite trend in natural populations of C. portentosa. Results obtained for C. portentosa collected from the N manipulation site Whim Moss indicated that ammonium is causal for the increase of two of the identified betaine lipids in natural populations in C. portentosa. Betaine lipids as well as the phosphatidylcholine biomarker could potentially be used to monitor nitrogen regimes and resulting phosphorus limitation on the lichen C. portentosa. The approach used for this study represented an effective integration of the complementary analytical techniques of FTIR and LC-MS in combination with multivariate statistical tools for environmental metabolomic studies.

Name dc:type.qualificationname

Doctor of Philosophy (awarded by OU/Aberdeen)

Level dc:type.qualificationlevel

Doctoral Thesis

Grantor dc:publisher.institution

University of Edinburgh

Year dc:date.issued

2011

Author dc:creator

• Freitag, Sabine

Advisors dc:contributor.advisor

• Boyd, Kenneth
• Gibb, Stuart
• Squier, Angela H.
• Feldmann, Jorg

Language dc:language

eng

Identifier

oai:pure.atira.dk:studenttheses/7f89f2c2-6671-40a4-beca-976d82791566

OAI identifier oai:identifier

oai:pure.atira.dk:studenttheses/7f89f2c2-6671-40a4-beca-976d82791566