The main aim was to investigate the cell-wall cross-links in Chinese water chestnut (CWC), in particular ferulic-acid-containing phenolic-polysaccharide cross-links. The secondary ~ims were: to understand the gross composition of C''!C cell walls froin the parenchyma, epidermis and sub-epidermis tissues of the corm and the -role of cell-wall composition in the plant's physiology, and to determine whether CWC contained higher oligomers of ferulic acid. Cell-wall composition was investigated using a range of chemical analyses including alkali phenolic extraction and methylation analysis. Chemical and biochemical methods were evaluated for their ability to produce oligosaccharide fragments attached to ferulic acid species. Mild acid hydrolysis followed by column chromatography using Biogel P-2 was the method chosen. lC-MS was used to identify compounds of interest. The compositions of the epidermal tissues differed particularly in the proportions of lignin and cellulose present. The relative amounts and proportions of the phenolics varied considerably, possibly indicating their functions in the different tissues. A multitude of phenolics were detected, a number of which now have detailed UV information recorded about them. The LC-MS results indicate that trimers and tetramers of ferulic acid are present, and provide some degree of structural information for the trimers. A reasonable level of solubilisation was achieved with mild acid hydrolysis, releasing ....70% of the arabinose, xylose and galactose present into the supernatant. LC-MS indicated that multiple species containing ferulic acid or diferulic acids linked to one or more pentose sugars are present in the TFA hydrolysate and Biogel P-2 fractions, indicating that ferulic acid and diferulic acid are linked to cell-wall sugars in CWC as in many other monocots. Trimers and tetramers of ferulic acid were detected in a nonmaize substrate for the first time, implying the possibility of higher oligomers of ferulic acid being present naturally in a wide range of cell walls.EThOS - Electronic Theses Online ServiceGBUnited Kingdo
