University of Oulu

Mansikkala, T., Patanen, M., Kärkönen, A., Korpinen, R., Pranovich, A., Ohigashi, T., … Piispanen, R. (2020). Lignans in Knotwood of Norway Spruce: Localisation with Soft X-ray Microscopy and Scanning Transmission Electron Microscopy with Energy Dispersive X-ray Spectroscopy. Molecules, 25(13), 2997. doi:10.3390/molecules25132997

Lignans in knotwood of Norway spruce : localisation with soft X-ray microscopy and scanning transmission electron microscopy with energy dispersive X-ray spectroscopy

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Author: Mansikkala, Tuomas1,2; Patanen, Minna1,2; Kärkönen, Anna3,4;
Organizations: 1Nano and Molecular Systems Research Unit, Faculty of Science, University of Oulu, P.O. Box 8000, FI-90014 Oulu, Finland
2Biocenter Oulu, P.O. Box 5000, University of Oulu, FI-90014 Oulu, Finland
3Production Systems, Natural Resources Institute Finland, Latokartanonkaari 9, FI-00790 Helsinki, Finland
4Viikki Plant Science Centre, Department of Agricultural Sciences, University of Helsinki, FI-00014 Helsinki, Finland
5Wood and Paper Chemistry Research Group, Laboratory of Natural Materials Technology, Åbo Akademi University, Porthansgatan 3, FI-20500 Turku/Åbo, Finland
6UVSOR facility, Institute for Molecular Science, 38 Nishigo-naka, Myodaiji, Okazaki, Aichi 444-8585, Japan
7SOLEIL Synchrotron, L'Orme des Merisiers, Saint-Aubin, P.O. Box 48, FR-91192 Gif-Sur-Yvette Cedex, France
8Nanomicroscopy Center, Department of Applied Physics, Aalto University, P.O. Box, 15100, FI-00076 AALTO, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 1.8 MB)
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Language: English
Published: Multidisciplinary Digital Publishing Institute, 2020
Publish Date: 2020-07-03


Lignans are bioactive compounds that are especially abundant in the Norway spruce (Picea abies L. Karst.) knotwood. By combining a variety of chromatographic, spectroscopic and imaging techniques, we were able to quantify, qualify and localise the easily extractable lignans in the xylem tissue. The knotwood samples contained 15 different lignans according to the gas chromatography-mass spectrometry analysis. They comprised 16% of the knotwood dry weight and 82% of the acetone extract. The main lignans were found to be hydroxymatairesinols HMR1 and HMR2. Cryosectioned and resin-embedded ultrathin sections of the knotwood were analysed with scanning transmission X-ray microscopy (STXM). Cryosectioning was found to retain only lignan residues inside the cell lumina. In the resin-embedded samples, lignan was interpreted to be unevenly distributed inside the cell lumina, and partially confined in deposits which were either readily present in the lumina or formed when OsO4 used in staining reacted with the lignans. Furthermore, the multi-technique characterisation enabled us to obtain information on the chemical composition of the structural components of knotwood. A simple spectral analysis of the STXM data gave consistent results with the gas chromatographic methods about the relative amounts of cell wall components (lignin and polysaccharides). The STXM analysis also indicated that a torus of a bordered pit contained aromatic compounds, possibly lignin.

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Series: Molecules
ISSN: 1420-3049
ISSN-E: 1420-3049
ISSN-L: 1420-3049
Volume: 25
Issue: 13
Article number: 2997
DOI: 10.3390/molecules25132997
Type of Publication: A1 Journal article – refereed
Field of Science: 114 Physical sciences
116 Chemical sciences
1183 Plant biology, microbiology, virology
Funding: This research obtained funding from the Magnus Ehrnrooth Foundation (project “Biologisten näytteiden korkean resoluution spektromikroskooppinen tutkimus synkrotroni-ja elektronisäteilyä käyttäen”), Academy of Finland, and Biocenter Oulu “Emerging projects”-program. The research leading to this result has been supported by the project CALIPSOplus under the Grant Agreement 730872 from the EU Framework Programme for Research and Innovation HORIZON 2020.
Dataset Reference: Supplementary material:
Copyright information: © 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (