Arrangement of Cell-Wall Constituents in Chemically Treated Norway Spruce Tracheids
Keywords:
Cell-wall structure, interactions of cell-wall components, S2 layer, chemical treatment, FE-SEM, TEMAbstract
The cell-wall of tracheids in conifer wood has evolved to provide both water conduction and mechanical strength to the standing tree. However, its structure at the nanometer level is not yet accepted beyond doubt, and little is known about the interactions between the cell-wall components. In the present study, the fracture pattern of the S2 layer of Norway spruce tracheids was observed by field emission scanning electron microscopy (FE-SEM) after pretreatment of the cell wall with various alkali solutions, acetic and nitric acid, and ASAM delignification. The resulting cell-wall arrangements were also studied in ultra-thin sections of unfractured samples with transmission electron microscopy (TEM). In the case of untreated samples (reference), radial fracture patterns—perpendicular to the compound middle lamella—were regularly observed. A treatment with 10% and 18% NaOH or 24% KOH at room temperature—associated with a slight decrease of glucomannan—resulted in the disappearance of these radial fracture formations. As the severity of the alkali treatment increased and acid and ASAM delignification was applied, concentric alignments in the cell wall became more and more discernable. The increasing loss of hemicelluloses and lignin therefore led to distinct changes in the fragmentation patterns of the cell walls. In addition, reduction in strength and stiffness were determined for all chemically treated cell walls. It is concluded that even slight changes in cell-wall constitution influence the interactions of the cell-wall components and thus fracture mechanics and ultrastructural appearance of wood cell walls.References
Booker, R. E., and J. Sell. 1998. The nanostructure of the cell wall of softwoods and its functions in a living tree. Holz Roh-Werkst.56:1-8.nBorysiak, S., and B. Doczekalska. 2005. X-ray diffraction study of pine wood treated with NaOH. Fibres & Textiles in Eastern Europe13(5):87-89.nDaniel, G., and T. Nilsson. 1984. Studies on the S2 layer of Pinus sylvestris. Report 154, Department of Forest Products, Uppsala, Sweden. 34 pp.nDonaldson, L., and A. Frankland. 2004. Ultrastructure of iodine treated wood. Holzforschung58(3):219-225.nFahlén, J., and L. Salmén. 2002. On the lamellar structure of the tracheid cell wall. Plant Biology4(3):339-345.nFengel, D., and G. Wegener. 1989. Wood-chemistry, ultrastructure, reactions. De Gruyter, Berlin, Germany. 613 pp.nFratzl, P., I. Burgert, and H. S. Gupta. 2004. On the role of interface polymers for the mechanics of natural polymeric composites. Physical Chemistry Chemical Physics6(24):5575-5579.nFratzl, P., I. Burgert, and J. Keckes. 2004. Mechanical model for the deformation of the wood cell wall. Zeitschrift für Metallkunde95(7):579-584.nJungnickl, K. 2006. Personal Communication.nKeckes, J., I. Burgert, K. Frühmann, M. Müller, K. Kölln, M. Hamilton, M. Burghammer, S. von Roth, S. Stanzl-Tschegg, and P. Fratzl. 2003. Cell-wall recovery after irreversible deformation of wood. Nature Materials2:810-812.nKerr, A. J., and D. A. I. Goring. 1975. Ultrastructural arrangement of the wood cell wall. Cellulose Chem. Technol.9:563-573.nKim, N.-H. 2005. An investigation of mercerization in decayed oak wood by white rot fungus (Lentinula edodes). J. Wood Science51:290-294.nKöhler, L., and H.-C. Spatz. 2002. Micromechanics of plant tissues beyond the linear-elastic range. Planta215: 33-40.nLiese, W. 1970. Elektronenmikroskopie des Holzes. Pages 109-170 in H. Freund, Handbuch der Mikroskopie in der Technik. Umschau-Verlag, Frankfurt, Germany.nLonikar, S. V., N. Shiraishi, and T. Yokota. 1984. Effect of the loosening of the wood texture on the mercerization of cellulose in wood. J. of Wood Chem. Technol.4(4): 483-496.nMansikkamäki, P., M. Lahtinen, and K. Rissanen. 2005. Structural changes of cellulose crystallites induced by mercerisation in different solvent systems; determined by powder X-ray diffraction method. Cellulose12:233-242.nMattheck, C. 1991. Trees, the mechanical design. Springer, Berlin, Heidelberg, New York.nNishiyama, Y., S. Kuga, and T. Okano. 2000. Mechanism of mercerization revealed by X-ray diffraction. J. Wood Science46:452-457.nOkano, T., and A. Sarko. 1984. Mercerization of cellulose. I. X-ray diffraction evidence for intermediate structures. J. Appl. Polym. Sci.29:4175-4182.nRevol, J.-F., and D. A. I. Goring. 1981. On the mechanism of the mercerization of cellulose in wood. J. Appl. Polym. Sci.26:1275-1282.nReynolds, E. S. 1963. The use of lead citrate at high pH as an electron-opaque stain in electron microscopy. J. Cell Biology17:208.nRuel, K. F., and D. A. I. Goring. 1978. Lamellation in the S2 layer of softwood tracheids as demonstrated by scanning transmission electron microscopy. Wood Sci. Technol.12:287-291.nSalmén, L., and A. M. Olsson. 1998. Interaction between hemicelluloses, lignin and cellulose: Structure-property relationships. J. Pulp Paper Sci.24(3):99-103.nSchwarze, F. W. M. R., and J. Engels. 1998. Cavity formation and the exposure of peculiar structures in the secondary wall (S-2) of tracheids and fibres by wood degrading basidiomycetes. Holzforschung52(2):117-123.nSell, J. 1989. Eigenschaften und Kenngrössen von Holzarten. Baufachverlag AG, Zürich. 80 pp.nSell, J., and T. Zimmermann. 1993. Radial fibril agglomerations of the S2 on transverse-fracture surfaces of tracheids of tension-loaded spruce and white fir. Holz Roh-Werkst.51:384.nSell, J., and T. Zimmermann. 1998. The fine structure of the cell wall of hardwoods on transverse- fracture surfaces. Holz Roh-Werkst.56(5):365-366.nSingh, A. P., and G. Daniel. 2001. The S2 layer in the tracheid walls of Picea abies wood: Inhomogeneity in lignin distribution and cell wall microstructure. Holzforschung55(4):373-378.nSpurr, A. R. 1969. A low-viscosity epoxy resin embedding medium for electron microscopy. J. Ultrastructure Res.26(1-2):31 ff.nUremovic, A., T. Dokk Glawischnig, J. Schuseil, B. Saake, A. Borchmann, A. Herrmann, and J. Puls. 1994. Chromatographische Untersuchungen zur quantitativen Bestimmung der Holzzucker. Holz Roh-Werkst.52:347-354.nZimmermann, T., V. Thommen, P. Reimann, and H. J. Hug. 2006. Ultrastructural appearance of embedded and polished wood cell walls as revealed by Atomic Force Microscopy. J. Structural Biol.156:363-369.n
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