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Title: Arabinogalactans in Arabidopsis : structure and synthesis
Author: Barton, C. J.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2006
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The arabinogalactans are a class of plant cell wall polysaccharides rich in the arabinosyl and galactosyl residues. The synthesis of the arabinogalactans is not well understood at a molecular genetic level. In this work, qualitative techniques were developed for the analysis of both classes of arabinogalactan (type I and II) in Arabidopsis using high-resolution oligosaccharide profiling strategies. An assay for pectic arabinogalactan I was developed using specific enzymatic digestion and oligosaccharide profiling by polysaccharide analysis using carbohydrate electrophoresis (PACE). Arabinogalactan II was studied using a chemical digestion strategy followed by compositional analysis and oligosaccharide profiling with high performance liquid chromatography and tandem mass spectrometry. These techniques were then applied to study the structure and quantity of arabinogalactan I and II in a range of Arabidopsis organs for the first time. This revealed interesting structural features, including the presence of galacturonic acid on arabinogalactan II. The techniques were validated by analysis of previously characterized nucleotide sugar synthesis mutants with arabinogalactan defects. This revealed the channelling of sugars from nucleotide sugar donors into different polysaccharide pools. These and other techniques were then used to study the synthesis of wall polysaccharides, testing the hypothesis that the Cs1A family of plant glycosyltransferases were arabinogalactan synthases. The sequence and expression of selected Cs1A genes was characterized, and mutant Arabidopsis plant lines with genetic lesions in these genes were studied. In summary, this thesis describes both the development and application of tools to learn more about arabinogalactans structure and polysaccharide synthesis in the model organism, Arabidopsis.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available