Article

Xylem parenchyma cell walls lack a gravitropic response in conifer compression wood

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Abstract

Main conclusion: Cell wall fluorescence and immunocytochemistry demonstrate that xylem parenchyma cell walls do not show changes in structure and composition related to gravitropic response comparable to those of tracheids, even when they have lignified secondary cell walls. Tracheid cell walls in compression wood have altered composition and structure which generates the strain responsible for correction of stem lean as part of the gravitropic response of woody plants. Xylem parenchyma cell walls vary among conifer species and can be lignified secondary walls (spruce) or unlignified primary walls (pine). It can be expected that xylem parenchyma with lignified secondary cell walls might show features of compression wood comparable to those of tracheids that have a similar type of cell wall. A comparison of xylem parenchyma cell walls in normal and compression wood in species with lignified and non-lignified parenchyma cell walls provides a unique opportunity to understand the process of reaction wood formation in conifers. Using both UV/visible fluorescence microscopy of cell wall fluorophores and immunocytochemistry of galactan and mannan epitopes, we demonstrate that xylem parenchyma cell walls do not show the changes in composition and structure typical of compression wood tracheids. Adjacent cells of different types but with similar cell wall structure can undergo cell wall developmental changes related to support or defence functions independent of their neighbours. Tracheids are sensitive to gravitropic signals while xylem parenchyma cells are not.

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... Relatively few studies have characterized plant autofluorescence [1][2][3]6,19,20,[31][32][33][34]. Lignin is the only cell wall-associated fluorophore that has been investigated in detail [19], although some limited information is available for hydroxycinnamic acids such as coumarate and ferulate [20,26], as well as suberin [33]. ...
... Relatively few studies have characterized plant autofluorescence [1][2][3]6,19,20,[31][32][33][34]. Lignin is the only cell wall-associated fluorophore that has been investigated in detail [19], although some limited information is available for hydroxycinnamic acids such as coumarate and ferulate [20,26], as well as suberin [33]. ...
... We did not find evidence for suberin in the endodermis of radiata pine [4]. Interestingly, the resin canal epithelium in needle resin canals appears to lack the suberization found in resin canals in secondary xylem [33]. Suberin is much easier to detect by autofluorescence than by Sudan IV staining, which tends to be weak in conifer tissues, especially in comparison to cutin, which reacts strongly with this stain (Figure 1c). ...
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... Chlorophyll, cutin, suberin and various polyphenols including lignin are naturally fluorescent substances in plant cells (Rost 1995;Hutzler et al. 1998;Donaldson et al. 2015;García-Plazaola et al. 2015;Talamond et al. 2015). Autofluorescence (indigenous fluorescence) can be a significant problem when it overlaps with the fluorescence label on structures targeted for observation. ...
... Berberine hemisulfate (BH) and FY are commonly used fluorescent stains for lipids and suberin in the traditional plant anatomy (Brundrett et al. 1991;Lux et al. 2005). Sudan IV can fluorescently stain suberin with excitation/emission 561 nm/600-700 nm which was used to differentiate suberin from lignin (Donaldson et al. 2015). Nile red has been introduced as a lipophilic dye by King (1947) and Greenspan et al. (1985), and recently Nile red has been selected for staining of endodermis in Arabidopsis roots because of the compatibility of this dye with the tissue-clearing medium Downloaded from https://academic.oup.com/aobpla/article/12/4/plaa032/5864598 by guest on 10 August 2020 'ClearSee' (Ursache et al. 2018). ...
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Investigating plant structure is fundamental in botanical science and provides crucial knowledge for the theories of plant evolution, ecophysiology and for the biotechnological practices. Modern plant anatomy often targets the formation, localization and characterization of cellulosic, lignified or suberized cell walls. While classical methods developed in the 1960s are still popular, recent innovations in tissue preparation, fluorescence staining and microscopy equipment offer advantages to the traditional practices for investigation of the complex lignocellulosic walls. Our goal is to enhance the productivity and quality of microscopy work by focusing on quick and cost-effective preparation of thick sections or plant specimen surfaces and efficient use of direct fluorescent stains. We discuss popular histochemical microscopy techniques for visualization of cell walls, such as autofluorescence or staining with calcofluor, Congo red (CR), fluorol yellow (FY) and safranin, and provide detailed descriptions of our own approaches and protocols. Autofluorescence of lignin in combination with CR and FY staining can clearly differentiate between lignified, suberized and unlignified cell walls in root and stem tissues. Glycerol can serve as an effective clearing medium as well as the carrier of FY for staining of suberin and lipids allowing for observation of thick histological preparations. Three-dimensional (3D) imaging of all cell types together with chemical information by wide-field fluorescence or confocal laser scanning microscopy (CLSM) was achieved.
... Lignin and mannan were shown to be negatively colocalized in both normal and compression wood whereas lignin and galactan were positively colocalized in compression wood but not in normal wood [34]. Similar studies have shown that, in spruce wood, resin canal parenchyma cells with lignified secondary cell walls do not show a reaction wood response (increased lignin and galactan content) compared to adjacent tracheids [49]. ...
... Suberin, like cutin, is a hydrophobic polyester consisting of long-chain fatty acids and glycerol [67]. It exhibits UV-excited autofluorescence comparable to lignin, from which it can be distinguished by its weak blue-excited autofluorescence relative to lignin ( Figure 6) [15,49]. In sequentially UV/blue-excited images, suberin will show violet/blue emission, while lignin will show blue/green emission, although both lignin and suberin may be colocalized and hence indistinguishable in some tissues (endodermis, epidermis, Casparian strips). ...
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Plants contain abundant autofluorescent molecules that can be used for biochemical, physiological, or imaging studies. The two most studied molecules are chlorophyll (orange/red fluorescence) and lignin (blue/green fluorescence). Chlorophyll fluorescence is used to measure the physiological state of plants using handheld devices that can measure photosynthesis, linear electron flux, and CO2 assimilation by directly scanning leaves, or by using reconnaissance imaging from a drone, an aircraft or a satellite. Lignin fluorescence can be used in imaging studies of wood for phenotyping of genetic variants in order to evaluate reaction wood formation, assess chemical modification of wood, and study fundamental cell wall properties using Förster Resonant Energy Transfer (FRET) and other methods. Many other fluorescent molecules have been characterized both within the protoplast and as components of cell walls. Such molecules have fluorescence emissions across the visible spectrum and can potentially be differentiated by spectral imaging or by evaluating their response to change in pH (ferulates) or chemicals such as Naturstoff reagent (flavonoids). Induced autofluorescence using glutaraldehyde fixation has been used to enable imaging of proteins/organelles in the cell protoplast and to allow fluorescence imaging of fungal mycelium.
... Another important factor is the availability of genetic material of the tissue analyzed, if the DNA extraction is successful in wood tissue compared to leaf (Japelaghi et al. 2011), the results indicate a greater amount of isolation in leaf tissue, since DNA isolation increases with the availability of parenchymal cells, finding a greater number of these cells in leaf tissue than in wood . The wood parenchyma membrane comprises an average lamina and three cell walls (S1, S2 and S3) (Donaldson et al. 2015), and its composition varies among them, being lignin, cellulose, hemicelluloses, peptides, proteins, and fat, the main components (Funda et al. 2020), making it difficult to isolate DNA through wood. ...
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... Cellulose in cell walls can be visualised by staining with calcofluor white which is one of the most commonly used fluorescent stains (Sato et al. 2001;Mitra & Loque 2014;Chai et al. 2015). FM is often employed to screen compression and normal wood (Donaldson et al. 2010(Donaldson et al. , 2015Donaldson & Knox 2012;Donaldson & Singh 2016). As an example, FM can be used to quantify the severity of compression wood using the ratio between the fluorescence produced at blue and violet wavelengths (Donaldson et al. 2010). ...
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... Ferulic acid (monomers and dimers) forms intra-and/or intermolecular bridges between lignin fragments (Sun et al. 2002), linked with arabinoxylans (Ishii and Hiroi 1990), or arabinose, allowing cross-linking between xylan chains (Ishii 1991) and linkages to lignin (Scalbert et al. 1985;Ralph et al. 1992;Grabber et al. 2002). Compared to the presented structural changes in parenchyma cell walls of D. balcanica related to stem twining, the opposite was found in parenchyma cell walls of Picea omorika and radiata pine resin canals (Donaldson et al. 2015). No structural or compositional differences related to stem lean were found in cell walls of resin canal parenchyma cells by means of histochemistry, autofluorescence, and immunocytochemistry. ...
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... Древесная клетка -это упругопластичный материал, который может изменять свои размеры и свойства. [1,2,3,4] Изменение размеров клетки происходит в двух случаях: при внешнем воздействии и при её росте, делении и т. д. Внешнее воздействие возможно за счет прессования, сжатия или внедрения в древесину различных пуансонов, что приводит к частичной или полной деформации структуры древесины, в том числе и древесных клеток (рис. ...
... While chitin and 1,3-beta-glucans are main components of fungi cell wall 23 , cellulose and the other substrates for the identified increased glycoside hydrolases in B. xylophilus secretome are components of plant cell walls. Xylem parenchyma cell walls vary among conifer species and in Pinus species are mostly thin-walled and unlignified primary walls comprising cellulose, hemicelluloses, pectins and lesser amounts of structural proteins 24,25 . The increased of these cell wall degrading enzymes in B. xylophilus secretome compared to B. mucronatus may reflect a higher capacity of this species to the feed on both plant cells and fungi colonizing trees. ...
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... All spectra were acquired at the same gain, so that brightness was comparable among samples. Average spectra were compared using the Chi-squared test and the Kolmogorov-Smirnov test to detect significant differences (Donaldson et al. 2015). ...
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Key message A technique whereby whole mounts of delicate tissues of differentiating xylem are imaged directly by polishing and block-face imaging of embedded microcores. Autofluorescence and image analysis aids identifying the stages of xylogenesis. Abstract Stem microcores from fast-growing trees, such as Pinus radiata (D. Don) with wide zones of cambium and differentiating xylem and very wide growth rings, pose a challenge for microscopy, as they are difficult to handle and easily damaged compared to slower growing species. A novel procedure has been developed which captures high-resolution images directly from the block face of large samples embedded in plastic resin without the need for sectioning or staining. Microcores of differentiating xylem of P. radiata growing in the central North Island of New Zealand were embedded in a low viscosity acrylic resin. The surface of the entire resin block was abraded and polished to expose cross sections of the wide zone of wood formation in these fast-growing trees without damage or distortion. Autofluorescence imaging was performed using a confocal laser scanning microscope. This avoided the need for staining and allowed the determination of the beginning of lignification based on lignin autofluorescence. Image analysis was used to determine the widths of: (a) the cambium, cell expansion, and wall-thickening zone (CET) and (b) the wall lignification zone (LT). A fast-growing tree had wider CET and LT zones than a slow-growing tree. This was due to the fast-growing tree producing more tracheids than the slow-growing tree, rather than by the production of larger tracheids.
... EgMYB1 and EgH1.3 are also co-expressed in mature rays and in paratracheal cells surrounding vessels. These two kinds of xylem parenchymatous cells have thin secondary cells walls with a different structure from that of fibres and vessels (Chafe & Chauret, 1974;Donaldson et al., 2015); in some species, they entirely lack lignin. These cells can remain alive for several years until the formation of heartwood (D ejardin et al., 2010). ...
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Chapter
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Norway spruce (Picea abies L. Karst) produces an oleoresin characterized by a diverse array of terpenoids, monoterpenoids, sesquiterpenoids, and diterpene resin acids that can protect conifers against potential herbivores and pathogens. Oleoresin accumulates constitutively in resin ducts in the cortex and phloem (bark) of Norway spruce stems. De novo formation of traumatic resin ducts (TDs) is observed in the developing secondary xylem (wood) after insect attack, fungal elicitation, and mechanical wounding. Here, we characterize the methyl jasmonate-induced formation of TDs in Norway spruce by microscopy, chemical analyses of resin composition, and assays of terpenoid biosynthetic enzymes. The response involves tissue-specific differentiation of TDs, terpenoid accumulation, and induction of enzyme activities of both prenyltransferases and terpene synthases in the developing xylem, a tissue that constitutively lacks axial resin ducts in spruce. The induction of a complex defense response in Norway spruce by methyl jasmonate application provides new avenues to evaluate the role of resin defenses for protection of conifers against destructive pests such as white pine weevils (Pissodes strobi), bark beetles (Coleoptera, Scolytidae), and insect-associated tree pathogens.
Book
The structural complexity of lignin has continually challenged the in­ genuity of researchers to develop suitable methods for its charac­ terization prior to and following a wide variety of chemical, biologi­ cal, and physical treatments. Initially, activity along these lines was fueled by a desire to interpret technical delignification (Le. , pulping) processes in terms of accompanying structural changes in the lignin. Subsequently, increasingly wide ranging, in-depth investigations on the structure and reactivity of lignin exposed the inadequacy of many of the methods currently in use and underscored the ever-continuing need to develop new methods capable of solving the unique analytical problems associated with lignin. Characteristically, such methods should be selective, sensitive, suitable for quantitative measurements, and capable of being applied directly to, and without destruction of, the lignin or lignocellulose sample. One notable example of the head­ way being made in reaching this objective is the relatively recent devel­ opment and refinement of methods based on the use of sophisticated instrumentation, e. g. , lH_ and 13C-NMR spectroscopy. Although the utility of many of these and other recently developed methods de­ scribed in this book has yet to be fully and satisfactorily exploited, we believe that progress already made in this direction will continue and most likely accelerate. The decision to produce this book was prompted mainly by the acknowledged need for an up-to-date, single source compilation of lignin methodology. Hitherto, this need was, in part, satisfied by B. L.
Article
Key message Young P. omorika trees subjected to static bending showed a severe compression wood response as characterized by fluorescence spectroscopy/microscopy, which decreased in severity with height correlated with a decrease in bending moment. Abstract This investigation is aimed at understanding the reaction wood response in a slow-growing conifer species under conditions of severe and long-term bending stress. Compression wood (CW) formation was studied in stems of juvenile P. omorika after trees were subjected to static bending by wiring at an angle of about 90 degrees, for 1 year. The applied static bending would correspond to the impact of winter snow loads or snow falls on juvenile conifers. Stem sections were collected during one growing season and examined by fluorescence microscopy, and fluorescence spectroscopy including deconvolution analysis. Trees exposed to bending produced large amounts of severe CW but very low amounts of opposite wood (OW) during the experimental season indicating a dramatic change in biomass distribution compared to control trees. Indicators of cell wall structure changes, such as fluorescence emission spectra, peak intensities, and shifts in the positions of the long-wavelength spectral components, decreased from the stem base to the top of the stem, in line with a calculated decrease in bending moment.
Article
Compression wood and opposite wood formed in the branch of Korean pine (Pinus koraiensis S. et Z.) is described and compared in qualitative and quantitative anatomical aspects. The qualitative features of compression wood appeared to differ from those of opposite wood in tracheid transition from earlywood to latewood, growth ring width, latewood proportion, tracheid shape in cross and radial section, intercellular spaces, traumatic resin canals, helical cavities, distribution of vertical epithelium, shape of fusiform rays and cross field pits. In quantitative features there are differences between these two tissues in length and wall thickness of tracheids, in number of vertical and horizontal resin canals (fusiform rays), in width and height of fusiform rays, in number and height of uniseriate rays and in the number of biseriate rays.
Article
The lignification process from sapwood (sW) to heartwood (hW) in ray parenchyma cells (Pray) of Pinus densiflora has been analyzed by means of ultraviolet (UV) microscopy, acetyl bromide (CH3COBr) lignin determination, and time-of-flight secondary ion mass spectrometry (TOF-SIMS). The cell wall layers were localized by polarized optical microscopy (POM). POM revealed that Pray have almost no secondary wall in sW and have only the outer layer of secondary wall (S1) in the transition zone (TZ) and hW. UV microscopic observations indicated that the secondary wall of Pray, which is in contact with ray tracheids (Trray), begins to lignify in sW, while the secondary wall of Pray, which is not in contact with Trray, is partially lignified in the TZ. The secondary wall of both types of Pray is completely lignified in hW. The CH3COBr lignin content in sW is slightly lower than that in hW. In the TOF-SIMS measurements, the relative intensities of the secondary ions of guaiacyl-lignin (G-lignin) in the rays in sW are significantly lower than those in hW.
Article
The ray parenchyma cell walls of Pinus radiata are non-absorbing to ultraviolet light in the sapwood but strongly absorbing in the heartwood. These observations confirm that the ray parenchyma cell walls in the sapwood of the Diploxylon section of the genus Pinus are not lignificd and support the view that they become lignified in the heartwood.
Article
The lignification of ray parenchyma cells in the sapwood (sW) and heartwood (hW) of Pinus densiflora was investigated by thioacidolysis and the subsequent Raney nickel desulfuration. The samples rich and less rich in ray parenchyma cells were prepared by laser microdissection (LMD). The whole sections burned randomly by the laser served as the controls. Guaiacyl (G) monomers were detected in all the samples, and p-hydroxyphenyl (H) monomers were detectable only in trace amounts, while syringyl (S) units were absent, as expected in softwood. In sW samples rich in ray parenchyma cells, the yields of G monomers are significantly lower than in the other samples. The various types of G-G and one G-H dimers were detected, and the β-1′, β-5′, and 5-5′ dimers were dominant. The relative distributions of lignin interunit linkages were very similar in all the samples regardless of the abundance of the ray parenchyma cells in the sW or hW tissues.
Article
Axial resin canals in wood are distinguished into two types based on the morphology of epithelial cells; resin canals with narrow canals and thick-walled epithelial cells (Type I), and resin canals with wide canals and thin-walled epithelial cells (Type II). Following studies on Norway spruce (Type I), the distribution of non-cellulosic polysaccharides in axial resin canals of Scots pine (Type II) is reported here using cytochemical and immunocytochemical methods. The distribution of (1→4)-β-galactan (LM5), (1→5)-α-arabinan (LM6), homogalacturonan (LM19, LM20), xyloglucan (LM15), xylan (LM10, LM11) and mannan (LM21, LM22) epitopes were examined. Axial resin canal complexes in the xylem were composed of canal, epithelium and subsidiary cells (parenchyma and strand tracheids). Strand tracheids were absent in axial resin canals in the phloem. Strand tracheids showed a completely different ultrastructure and chemistry from normal mature tracheids and other types of axial resin canal cells. Immunolocalization of non-cellulosic polysaccharides in axial resin canals showed an overall similar cell wall composition in epithelial cells and subsidiary parenchyma between the xylem and phloem. All types of axial resin canal cells in both xylem and phloem contained homogalacturonan (HG), rhamnogalacturonan-I (RG-I) and xyloglucan with a high variation in amount and chemical structure depending on cell wall region and between cell types. In particular, epithelial cell walls facing the canal showed significant differences in HG distribution from other epithelial cell wall regions. No xylan and mannan epitopes were detected in any of axial resin canal cells. Together, our results suggest that the chemistry of axial resin canal cells in Scots pine may be highly compartmentalized depending on functional differences between both cell types and cell wall regions.
Article
The microdistribution of non-cellulosic polysaccharides in epithelial cells of axial resin canals was investigated in Norway spruce xylem using immunolocalization methods combined with monoclonal antibodies specific for (1→4)-β-galactan (LM5), (1→5)-α-arabinan (LM6), homogalacturonan (LM19, LM20), xyloglucan (LM15), xylan (LM10, LM11) and mannan (LM21, LM22). The ultrastructure and lignin distribution of epithelial cell walls was also examined after cytochemical staining for lignin. Compared with tracheids, epithelial cells showed several different ultrastructural characteristics, such as the thickness of three layers forming the cell wall, the boundary structure between layers and the lamellate structure of cell walls, with slightly stronger reaction with chemical staining for lignin than tracheids. After staining with potassium permanganate, the layer of the epithelial cell wall adjacent to the canal showed typical characteristics of middle lamella (C-ML). However, C-ML regions showed completely different chemical characteristics from E-ML (middle lamella between epithelial cells) regions of epithelial cells and compound middle lamella (CML) regions of tracheids. Unlike tracheids, epitopes of pectic polysaccharides were detected in the epithelial cell wall with variations in amounts between cell wall layers. Epitopes of hemicelluloses were also detected in the epithelial cells with differences in distribution patterns from tracheids, particularly xyloglucan (LM15) and low substituted xylan (LM10) epitopes. Together, our results suggest that the ultrastructure and chemistry of epithelial cells including C-ML regions significantly differ from tracheids.
Chapter
Compression wood is a hard, dark-coloured wood typically found on the lower side of leaning stems and branches in conifers, Taxus and Ginkgo. This reaction wood is the result of the geotropic response of the tree, usually resulting from stem lean or the effect of stem flexing caused by wind. Compression wood is characterised by anatomical and compositional features that vary in a continuum between normal wood and severe compression wood. The main characteristics of compression wood are altered cell wall structure especially increased microfibril orientation, presence of helical cavities and intercellular spaces and increased lignification associated with significant amounts of (1 → 4)-β-galactan in the secondary wall. This chapter briefly reviews the formation, structure and composition of compression wood with an emphasis on recent advances.
Article
Summary A protocol is outlined for histochemical de­ tection of intracellular suberin linings on the inner surface of the cell walls in impervious tis­ sues of wounded and infected bark, and in bark forming rhytidome. Thin intracellular suberin linings (circa 0.5 J.LIl1) were detected in allIS woody angiosperms examined. Intracellular suberisation was strongly associated with indi­ vidual cells or cell layers (boundary zone) that displayed imperviousness with fluid diffusion tests. Tests include use of phloroglucinol + HO and Sudan black B to selectively quench auto­ fluorescence of lignin and suberin, respectively. Blue-violet excitation is used to enhance the
Article
SUMMARY The terminology related to axial resin canals in conifers is briefly re- viewed, standard terms are clarified and a new term is proposed. The definitions proposed are intended primarily for light microscopic ob- servations. All the cells and spaces of an axial resin canal as differenti- ated from the axial tracheids are collectively referred to as the resin canal complex. The resin canal is the intercellular space itself, and the epithelium is the uniseriate layer of cells lining the canal. We propose the term subsidiary cells to include all cells exterior to the epithelium, which may be subsidiary parenchyma and /or strand tracheids.
Article
Wood cell walls are naturally fluorescent due to the presence of lignin. Autofluorescence offers a more specific method for localising lignin than staining and can potentially be used to assess cell wall modification resulting from a range of biological, chemical and physical treatments. In order to optimise conditions for imaging lignin by autofluorescence and to evaluate possible differences in fluorescence between softwood and hardwood lignin, wood sections of radiata pine and poplar were examined by confocal laser scanning microscopy to measure fluorescence spectra in a range of mounting media. Glycerol/buffer mixtures at three different pH values were compared with immersion oil and thiodiethanol using both UV and visible excitation. Glycerol/buffer at pH9 produced the strongest lignin fluorescence at visible excitation indicating that this is the optimal mounting medium for imaging and spectroscopy. For UV excitation, thiodiethanol gave increased brightness relative to glycerol. Poplar lignin was four times brighter than pine lignin with excitation at 488 nm at pH9, and showed characteristic differences in spectral emission under these conditions. This characteristic fluorescence was localised to the inner secondary wall of fibres, expressed as a gradient from the outer S2 region increasing towards the lumen, as visualised by spectral unmixing. Comparison with sapwood from other hardwood species suggests that this fluorescence emission is characteristic of poplar and willow (Salicaceae). Members of the Salicaceae family are known to contain characteristic syringyl p-hydroxybenzoate lignin and it is likely that this special lignin type is responsible for the characteristic pH dependant fluorescence of poplar fibre walls.
Article
The primary resin ducts in the axis of plants of Pinus halepensis Mill, consist of two separate systems the pattern of which is correlated with the vascular systems of the organs in which they appear. These systems are: (1) ducts of the roots and the hypocotyl; (2) ducts of all the branches and juvenile leaves or scaleS. Both systems are produced by the apical meristemS. In the needles there is a third system of primary resin ducts situated in the mesophyll. These ducts are produced only to a small extent by the apical meristem of the needle and mainly by its intercalary meristem. In addition to these primary ducts of the needle, which form a separate system for each needle, at the base of the needle there may be ducts of secondary origin which are situated within the vein. These are continuous with secondary ducts of the brachyblast axis. The secondary ducts constitute one system in the secondary xylem and phloem of the roots, branches and needle bases. They are formed by the cambium. In the xylem there are vertical and radial ducts which together form co-planar radial networkS. Each radial duct starts from a vertical duct. The first location of the stimulus for the formation of the two types of ducts is discussed. In the phloem there are only radial ducts, continuous with the radial ducts of the xylem. The cavities of the radial phloem and xylem ducts are not continuous, as there are no intercellular spaces in the region of the cambium. The innermost vertical ducts of the secondary xylem form a kind of transitional type, in respect of their response to internal and external factors, between the primary resin ducts and the bulk of the secondary resin ducts.
Article
Two trees of radiata pine, one showing severe lean, the other growing almost vertically, were assessed for the presence and anatomical properties of compression wood, including anatomy, lignin distribution, microfibril angle, basic density, radial and tangential lumen diameter and cell wall thickness. Both trees contained significant amounts of compression wood although the severity and amount of compression wood was greater in the leaning tree. Changes in lignin distribution seem to be characteristic of the mildest forms of compression wood with reduced lignification of the middle lamella representing the earliest change observed from normal wood. An increase in microfibril angle was associated with both mild and severe compression wood although examples of severe compression wood with the same or smaller microfibril angles than opposite wood, or with very small microfibril angles, were found. When segregated into mild and severe compression wood the average difference in microfibril angle was 4° and 8° respectively compared with opposite wood. Within-ring distribution of microfibril angle was different in severe compression wood compared to opposite wood with higher angles in the latewood. Severe compression wood showed a 22% increase in basic density compared to mild compression wood and opposite wood. The increased density was accounted for in terms of a 26% increase in tracheid wall thickness throughout the growth ring, offset by a 9% increase in radial lumen diameter, slightly greater in the latewood. There were no significant changes in density or cell dimensions in mild compression wood compared with opposite wood.
Article
 Resin ducts are common in the Pinaceae. The comparative anatomy of stems and leaves of 50 species and two varieties from ten genera has been investigated. The structure and distribution of resin ducts differ among genera. Resin ducts occur in foliage leaves of ten genera of Pinaceae. Cortical resin ducts are absent in the stems of Pseudolarix and Larix. Resin ducts only occur in the secondary xylem of stems of Pinus, Picea, Cathaya, Larix, Pseudotsuga and some Keteleeria species. All of the epithelial and sheath cells are alive and thin-walled in the resin ducts of stem cortex and mesophyll. Except for Pinus the epithelial cells of resin ducts in the secondary xylem of stems have thick, lignified walls. Comparative study shows there are obvious differences in the resin ducts of different genera; apparent differences do not exist, however, in the resin ducts of different species of the same genus. According to the structure and distribution of the resin ducts in ten genera of Pinaceae, a synoptical arrangement of the genera is given and generic relationships of the Pinaceae are discussed.
Article
The distribution of noncellulosic polysaccharides in cell walls of tracheids and xylem parenchyma cells in normal and compression wood of Pinus radiata, was examined to determine the relationships with lignification and cellulose microfibril orientation. Using fluorescence microscopy combined with immunocytochemistry, monoclonal antibodies were used to detect xyloglucan (LM15), β(1,4)-galactan (LM5), heteroxylan (LM10 and LM11), and galactoglucomannan (LM21 and LM22). Lignin and crystalline cellulose were localized on the same sections used for immunocytochemistry by autofluorescence and polarized light microscopy, respectively. Changes in the distribution of noncellulosic polysaccharides between normal and compression wood were associated with changes in lignin distribution. Increased lignification of compression wood secondary walls was associated with novel deposition of β(1,4)-galactan and with reduced amounts of xylan and mannan in the outer S2 (S2L) region of tracheids. Xylan and mannan were detected in all lignified xylem cell types (tracheids, ray tracheids, and thick-walled ray parenchyma) but were not detected in unlignified cell types (thin-walled ray parenchyma and resin canal parenchyma). Mannan was absent from the highly lignified compound middle lamella, but xylan occurred throughout the cell walls of tracheids. Using colocalization measurements, we confirmed that polysaccharides containing galactose, mannose, and xylose have consistent correlations with lignification. Low or unsubstituted xylans were localized in cell wall layers characterized by transverse cellulose microfibril orientation in both normal and compression wood tracheids. Our results support the theory that the assembly of wood cell walls, including lignification and microfibril orientation, may be mediated by changes in the amount and distribution of noncellulosic polysaccharides.
Article
Confocal fluorescence microscopy was used to examine the spectral characteristics of lignin autofluorescence in secondary cell walls of normal and compression wood from Pinus radiata. Using UV excitation, fluorescence spectra of normal and compression wood sections showed significant differences, especially in the outer secondary cell wall of tracheids, with a shift in maxima from violet to blue wavelengths between normal and compression wood. A comparison of normal wood, mild and severe compression wood, showed that the wavelength shift was intermediate in the mild compression wood compared to the severe compression wood, thus offering the possibility of quantifying the severity by measuring ratios of fluorescence at violet and blue wavelengths. Fluorescence induced by blue light, rather than UV, was less well differentiated amongst wood types. Spectral deconvolution indicated the presence of a minimum of five discrete lignin fluorophores in the cell walls of both normal and compression wood tracheids. Comparison with lignin model compounds suggest that the wavelength shift may correspond in part to increased levels of p-hydroxy type lignin in the compression wood samples. The combination of confocal fluorescence imaging and related spectral deconvolution therefore offers a novel technique for characterising cell wall lignin in situ.
Article
Cell wall structure in ray and axial parenchyma cells in the wood ofCryptomeria was shown to be typically crossed polylamellate and dissimilar to the characteristically layered wall of fibers and tracheids. Ray cells differed from axial cells in terms of form and also in the relative inclination of crossed microfibrillar helices in the cell wall. This feature was reflected by positive birefringence in ray cells and negative birefringence in axial cells. Localized wall thickenings,viz. transverse “bars” in ray cells and longitudinal “ribs” in axial cells, also displayed crossed polylamellate structure. This observation contrasts with the exclusively longitudinal microfibrillar orientation previously reported for longitudinal ribs in elongated parenchyma cells of primary tissue. On the basis of similar microfibrillar orientations between outer and inner wall lamellae, the cell walls ofCryptomeria parenchyma were judged to be predominantly secondary. Lignin was heterogeneously distributed in lamellate fashion and a high concentration characterized the thin middle lamella. Both types of parenchyma suggested a higher lignin content than adjacent longitudinal tracheids.
Article
In order to test whether lignin fluorescence originates from discrete fluorophores, fluorescence emission spectra of the lignin model dehydrogenative polymer (DHP) were analyzed by the band deconvolution method and time-resolved analysis of both the excitation and emission spectra. Two series of 22 fluorescence emission spectra of DHP in chloroform/methanol (3:1, v/v) solution, and as a solid suspension in water, were deconvoluted into three fluorescence and one Raman Gaussian components. Emission spectra were obtained by stepwise variation of the excitation wavelength from 360 to 465 nm. Deconvolution was performed by nonlinear fitting of all three Gaussian parameters: area, width and position. Position of all components in a series was treated as a random variable and its approximate probability distribution (APD) calculated from a series of histograms with increasing number of abscissa intervals. A five peak multimodal APD profile was obtained for both series of DHP emission spectra. The mean fluorescence lifetime varied with wavelength both in the emission and the excitation decay-associated spectra (DAS), where four kinetic components were resolved. The shapes of the excitation spectra of the four components were quite different and gradually shifted bathochromically. The multicomponent nature of the DHP emission spectra along with the changes in the mean fluorescence lifetime and the form of the excitation DAS of the four components give evidence of the heterogeneous origin of fluorescent species emitting in the visible.
Analysis of static bendinginduced compression wood formation in juvenile Picea omorika (Pancic) Purkyne. Trees Struct Funct. doi:10.1007/s00468-015- 1234- Wound-induced traumatic resin duct development in stems of norway spruce (Pinaceae): anatomy and cytochemical traits
  • Mitrovicmitrovic´mitrovic´a
  • La Donaldson
  • Djikanovicdjikanovic´djikanovic´d
  • J Bogdanovicbogdanovic´bogdanovic´pristov
  • Simonovicsimonovic´simonovic´j
  • Mutavdžicmutavdžic´mutavdžic´d
  • A Kalauzi
  • Maksimovicmaksimovic´maksimovic´v
  • B Nanayakkara
  • Radoticradotic´radotic´kz Nagy
  • Ne Franceschi
  • Vr Solheim
  • H Krekling
  • T Christiansen
MitrovicMitrovic´Mitrovic´A, Donaldson LA, DjikanovicDjikanovic´Djikanovic´D, BogdanovicBogdanovic´Bogdanovic´Pristov J, SimonovicSimonovic´Simonovic´J, MutavdžicMutavdžic´Mutavdžic´D, Kalauzi A, MaksimovicMaksimovic´Maksimovic´V, Nanayakkara B, RadoticRadotic´Radotic´K (2015) Analysis of static bendinginduced compression wood formation in juvenile Picea omorika (Pancic) Purkyne. Trees Struct Funct. doi:10.1007/s00468-015- 1234-z Nagy NE, Franceschi VR, Solheim H, Krekling T, Christiansen E (2000) Wound-induced traumatic resin duct development in stems of norway spruce (Pinaceae): anatomy and cytochemical traits. Am J Bot 87(3):302–313
Structure and formation of compression wood. In: Fromm J (ed) Cellular aspects of wood formation
  • L A Donaldson
  • A P Singh
Donaldson LA, Singh AP (2013) Structure and formation of compression wood. In: Fromm J (ed) Cellular aspects of wood formation. Plant Cell Monographs. Springer, Berlin, pp 225-256
Anatomy of stem and root wood of Pinus radiata D. Don
  • R N Patel
  • RN Patel
Patel RN (1971) Anatomy of stem and root wood of Pinus radiata D. Don. NZ J For Sci 1:37-49
Wall structure of parenchyma cells surrounding axial resin canals in the wood of European spruce
  • R R Sokal
  • F J Rohlf
  • Biometry
  • San Freeman
  • S Francisco Takahara
  • T Nobuchi
  • H Harada
  • H Saiki
Sokal RR, Rohlf FJ (1981) Biometry. WH Freeman, San Francisco Takahara S, Nobuchi T, Harada H, Saiki H (1983) Wall structure of parenchyma cells surrounding axial resin canals in the wood of European spruce. Mokuzai Gakkaishi 29:355-360