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Tracheid cell-wall structures and locations of (1   →   4)- β - d -galactans and (1   →   3)- β - d -glucans in compression woods of radiata pine ( Pinus radiata D. Don)

View Article: PubMed Central - PubMed

ABSTRACT

Background: Compression wood (CW) forms on the underside of tilted stems of coniferous gymnosperms and opposite wood (OW) on the upperside. The tracheid walls of these wood types differ structurally and chemically. Although much is known about the most severe form of CW, severe CW (SCW), mild CWs (MCWs), also occur, but less is known about them. In this study, tracheid wall structures and compositions of two grades of MCWs (1 and 2) and SCW were investigated and compared with OW in slightly tilted radiata pine (Pinus radiata) stems.

Results: The four wood types were identified by the distribution of lignin in their tracheid walls. Only the tracheid walls of OW and MCW1 had a S3 layer and this was thin in MCW1. The tracheid walls of only SCW had a S2 layer with helical cavities in the inner region (S2i). Using immunomicroscopy, (1 → 4)-β-D-galactans and (1 → 3)-β-D-glucans were detected in the tracheid walls of all CWs, but in only trace amounts in OW. The (1 → 4)-β-D-galactans were located in the outer region of the S2 layer, whereas the (1 → 3)-β-D-glucans were in the inner S2i region. The areas and intensities of labelling increased with CW severity. The antibody for (1 → 4)-β-D-galactans was also used to identify the locations and relative amounts of these galactans in whole stem cross sections based on the formation of an insoluble dye. Areas containing the four wood types were clearly differentiated depending on colour intensity. The neutral monosaccharide compositions of the non-cellulosic polysaccharides of these wood types were determined on small, well defined discs, and showed the proportion of galactose was higher for CWs and increased with severity.

Conclusion: The presence of an S3 wall layer is a marker for very MCW and the presence of helical cavities in the S2 wall layer for SCW. The occurrence and proportions of (1 → 4)-β-D-galactans and (1 → 3)-β-D-glucans can be used as markers for CW and its severity. The proportions of galactose were consistent with the labelling results for (1 → 4)-β-D-galactans.

Electronic supplementary material: The online version of this article (doi:10.1186/s12870-016-0884-3) contains supplementary material, which is available to authorized users.

No MeSH data available.


Related in: MedlinePlus

Micrographs of transverse sections of OW and three CWs showing tracheid wall structures. The main panels show transmission electron micrographs of OW (a), MCM1 (b), MCW2 (c) and SCW (d). In all wood types, the middle lamella is clearly differentiated from the primary wall (P) around the cells and at the cell corners (MLCC). All tracheid walls have a S1 and S2 layer, but an S3 layer is present in only OW (a) and MCW1 (b). Warts (W) are observed on the tracheid wall surface adjacent to the cell lumen in only OW (a). Helical cavities (HC) are present in the inner region of the S2 layer (S2i) in only SCW. Intercellular spaces (IS) are present between tracheids in only MCW 2 (c) and SCW (d). Micrographs obtained using a Leica confocal microscope. Scale bar: 1 μm. The insets show differential interference contrast micrographs. These particularly show the S1 and S3 layers in OW (a) and MCW1 (b) and helical cavities in SCW (d). All sections were from Tree 1. Scale bar: 5 μm
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Fig2: Micrographs of transverse sections of OW and three CWs showing tracheid wall structures. The main panels show transmission electron micrographs of OW (a), MCM1 (b), MCW2 (c) and SCW (d). In all wood types, the middle lamella is clearly differentiated from the primary wall (P) around the cells and at the cell corners (MLCC). All tracheid walls have a S1 and S2 layer, but an S3 layer is present in only OW (a) and MCW1 (b). Warts (W) are observed on the tracheid wall surface adjacent to the cell lumen in only OW (a). Helical cavities (HC) are present in the inner region of the S2 layer (S2i) in only SCW. Intercellular spaces (IS) are present between tracheids in only MCW 2 (c) and SCW (d). Micrographs obtained using a Leica confocal microscope. Scale bar: 1 μm. The insets show differential interference contrast micrographs. These particularly show the S1 and S3 layers in OW (a) and MCW1 (b) and helical cavities in SCW (d). All sections were from Tree 1. Scale bar: 5 μm

Mentions: Examination of transverse sections of tracheid walls of all four wood types using transmission electron microscopy showed differences in wall structures (Fig. 2). Total tracheid wall thickness increased progressively in the order OW, MCW1, MCW2 and SCW. In all the wood types, the ML and primary wall could be differentiated and were densely stained. S1 and S2 secondary wall layers were also evident in all wood types. A well defined S3 layer was present in OW (Fig. 2a) and a very thin S3 layer could just be discerned in MCW1 (Fig. 2b), but no S3 layers were found in MCW2 or SCW (Fig. 2c, d). Helical cavities were present in the inner region of the S2 layer (S2i) only in SCW (Fig. 2d). Warts were observed on the tracheid wall surface adjacent to the cell lumen only in OW (Fig. 2a).Fig. 2


Tracheid cell-wall structures and locations of (1   →   4)- β - d -galactans and (1   →   3)- β - d -glucans in compression woods of radiata pine ( Pinus radiata D. Don)
Micrographs of transverse sections of OW and three CWs showing tracheid wall structures. The main panels show transmission electron micrographs of OW (a), MCM1 (b), MCW2 (c) and SCW (d). In all wood types, the middle lamella is clearly differentiated from the primary wall (P) around the cells and at the cell corners (MLCC). All tracheid walls have a S1 and S2 layer, but an S3 layer is present in only OW (a) and MCW1 (b). Warts (W) are observed on the tracheid wall surface adjacent to the cell lumen in only OW (a). Helical cavities (HC) are present in the inner region of the S2 layer (S2i) in only SCW. Intercellular spaces (IS) are present between tracheids in only MCW 2 (c) and SCW (d). Micrographs obtained using a Leica confocal microscope. Scale bar: 1 μm. The insets show differential interference contrast micrographs. These particularly show the S1 and S3 layers in OW (a) and MCW1 (b) and helical cavities in SCW (d). All sections were from Tree 1. Scale bar: 5 μm
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC5015220&req=5

Fig2: Micrographs of transverse sections of OW and three CWs showing tracheid wall structures. The main panels show transmission electron micrographs of OW (a), MCM1 (b), MCW2 (c) and SCW (d). In all wood types, the middle lamella is clearly differentiated from the primary wall (P) around the cells and at the cell corners (MLCC). All tracheid walls have a S1 and S2 layer, but an S3 layer is present in only OW (a) and MCW1 (b). Warts (W) are observed on the tracheid wall surface adjacent to the cell lumen in only OW (a). Helical cavities (HC) are present in the inner region of the S2 layer (S2i) in only SCW. Intercellular spaces (IS) are present between tracheids in only MCW 2 (c) and SCW (d). Micrographs obtained using a Leica confocal microscope. Scale bar: 1 μm. The insets show differential interference contrast micrographs. These particularly show the S1 and S3 layers in OW (a) and MCW1 (b) and helical cavities in SCW (d). All sections were from Tree 1. Scale bar: 5 μm
Mentions: Examination of transverse sections of tracheid walls of all four wood types using transmission electron microscopy showed differences in wall structures (Fig. 2). Total tracheid wall thickness increased progressively in the order OW, MCW1, MCW2 and SCW. In all the wood types, the ML and primary wall could be differentiated and were densely stained. S1 and S2 secondary wall layers were also evident in all wood types. A well defined S3 layer was present in OW (Fig. 2a) and a very thin S3 layer could just be discerned in MCW1 (Fig. 2b), but no S3 layers were found in MCW2 or SCW (Fig. 2c, d). Helical cavities were present in the inner region of the S2 layer (S2i) only in SCW (Fig. 2d). Warts were observed on the tracheid wall surface adjacent to the cell lumen only in OW (Fig. 2a).Fig. 2

View Article: PubMed Central - PubMed

ABSTRACT

Background: Compression wood (CW) forms on the underside of tilted stems of coniferous gymnosperms and opposite wood (OW) on the upperside. The tracheid walls of these wood types differ structurally and chemically. Although much is known about the most severe form of CW, severe CW (SCW), mild CWs (MCWs), also occur, but less is known about them. In this study, tracheid wall structures and compositions of two grades of MCWs (1 and 2) and SCW were investigated and compared with OW in slightly tilted radiata pine (Pinus radiata) stems.

Results: The four wood types were identified by the distribution of lignin in their tracheid walls. Only the tracheid walls of OW and MCW1 had a S3 layer and this was thin in MCW1. The tracheid walls of only SCW had a S2 layer with helical cavities in the inner region (S2i). Using immunomicroscopy, (1 → 4)-β-D-galactans and (1 → 3)-β-D-glucans were detected in the tracheid walls of all CWs, but in only trace amounts in OW. The (1 → 4)-β-D-galactans were located in the outer region of the S2 layer, whereas the (1 → 3)-β-D-glucans were in the inner S2i region. The areas and intensities of labelling increased with CW severity. The antibody for (1 → 4)-β-D-galactans was also used to identify the locations and relative amounts of these galactans in whole stem cross sections based on the formation of an insoluble dye. Areas containing the four wood types were clearly differentiated depending on colour intensity. The neutral monosaccharide compositions of the non-cellulosic polysaccharides of these wood types were determined on small, well defined discs, and showed the proportion of galactose was higher for CWs and increased with severity.

Conclusion: The presence of an S3 wall layer is a marker for very MCW and the presence of helical cavities in the S2 wall layer for SCW. The occurrence and proportions of (1 → 4)-β-D-galactans and (1 → 3)-β-D-glucans can be used as markers for CW and its severity. The proportions of galactose were consistent with the labelling results for (1 → 4)-β-D-galactans.

Electronic supplementary material: The online version of this article (doi:10.1186/s12870-016-0884-3) contains supplementary material, which is available to authorized users.

No MeSH data available.


Related in: MedlinePlus