title: Identification of lignin and polysaccharide modifications in Populus wood by chemometric analysis of 2D NMR spectra from dissolved cell walls.
abstract: 2D 13C-(1)H HSQC NMR spectroscopy of acetylated cell walls in solution gives a detailed fingerprint that can be used to assess the chemical composition of the complete wall without extensive degradation. We demonstrate how multivariate analysis of such spectra can be used to visualize cell wall changes between sample types as high-resolution 2D NMR loading spectra. Changes in composition and structure for both lignin and polysaccharides can subsequently be interpreted on a molecular level. The multivariate approach alleviates problems associated with peak picking of overlapping peaks, and it allows the deduction of the relative importance of each peak for sample discrimination. As a first proof of concept, we compare Populus tension wood to normal wood. All well established differences in cellulose, hemicellulose, and lignin compositions between these wood types were readily detected, confirming the reliability of the multivariate approach. In a second example, wood from transgenic Populus modified in their degree of pectin methylesterification was compared to that of wild-type trees. We show that differences in both lignin and polysaccharide composition that are difficult to detect with traditional spectral analysis and that could not be a priori predicted were revealed by the multivariate approach. 2D NMR of dissolved cell wall samples combined with multivariate analysis constitutes a novel approach in cell wall analysis and provides a new tool that will benefit cell wall research.
authors.affiliation: Department of Chemistry, Umeå University, SE-90187 Umeå, Sweden. mattias.hedenstrom@chem.umu.se
authors.forename: Mattias
authors.initials: M
authors.lastname: Hedenström
authors.forename: Susanne
authors.initials: S
authors.lastname: Wiklund-Lindström
authors.forename: Tommy
authors.initials: T
authors.lastname: Oman
authors.forename: Fachuang
authors.initials: F
authors.lastname: Lu
authors.forename: Lorenz
authors.initials: L
authors.lastname: Gerber
authors.forename: Paul
authors.initials: P
authors.lastname: Schatz
authors.forename: Björn
authors.initials: B
authors.lastname: Sundberg
authors.forename: John
authors.initials: J
authors.lastname: Ralph
mesh_terms: D002473:Cell Wall / Q000737:chemistry* / Q000378:metabolism; D008031:Lignin / Q000737:chemistry*; D015999:Multivariate Analysis; D019906:Nuclear Magnetic Resonance, Biomolecular; D011134:Polysaccharides / Q000737:chemistry*; D032107:Populus / Q000737:chemistry*; D014934:Wood / Q000737:chemistry*
chemical_list: D011134:Polysaccharides; D008031:Lignin