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1.
Summary The formation of lignin in the cell wall of compression wood of Pinus thunbergii was examined by selective radio-labeling of specific structural units in the lignin and visualization of the label in the different morphological regions by microautoradiography. Deposition of lignin in the tracheid cell wall of compression wood occurred in the order: p-hydroxyphenyl, guaiacyl and syringyl lignin, which is the same order as observed in normal wood. However, the period of lignification in the compression wood was quite different from those of normal and opposite woods. The p-hydroxyphenyl units were deposited mainly in the early stage of cell wall formation in compound middle lamella in normal and opposite woods, while in compression wood, they were formed in both the compound middle lamella and the secondary wall. The most intensive lignification was observed during the formation of the S2 layer, proceeding from the outer to inner S2 layers for a long period in compression wood. In the normal or opposite woods, in contrast, the lignification became active after formation of S3 had begun, then proceeded uniformly in the secondary wall and ended after a short period.A part of this report was originally presented at the 1989 International Symposium on Wood and Pulping Chemistry at Raleigh, NC, U.S.A.  相似文献   

2.
Lignin deposition at consecutive secondary wall thickening stages of early and late xylem cells during annual ring wood formation in Scots pine (Pinus sylvestris L.) stems was studied. Lignin patterns, isolated by thioglycolic acid method, consisted of alcohol-soluble (LTGA-I) and alkali-soluble (LTGA-II) fractions. The sum of two fractions, being the total lignin content, gradually increased in the course of lignification. However, the increments of lignin amount at each development stage of early and late tracheids were different. The intensity of lignin deposition increased in the course of earlywood tracheid maturation and decreased toward the end of latewood cell differentiation. The deposition of two lignin fractions in each layer of forming wood also occurred oppositely. The increment of LTGA-I descended, whereas that of LTGA-II increased from the beginning to the end of early xylem lignification. In contrast, LTGA-I increment dropped, whereas LTGA-II rose during late xylem lignification. Gel permeation chromatography showed that the lignins, formed at the beginning of lignification, were more homogeneous and had higher molecular weight compared with the lignins at the end of cell differentiation. Besides, the content of cellulose, estimated as the residue after lignin isolation, and of cell wall substances, presented as cell wall cross-section areas, at consecutive maturation stages of early and late xylem cells have been found to be different. The data show that lignin deposition occurred in different conditions and with opposite dynamics during early and late xylem formation.  相似文献   

3.
Bamboos are among the largest woody grasses and grow very rapidly. Although lignin is a crucial factor for the utilization of bamboo biomass, the lignification mechanism of bamboo shoots is poorly understood. We studied lignification in the bamboo Sinobambusa tootsik during culm development. Elongation growth began in May and ended in late-June, when the lignin content was approximately half that in mature culms. Thioacidolysis analysis indicated that p-hydroxyphenyl units in lignin formed even at late stages of lignification. The syringyl/guaiacyl ratio varied during culm development. Various lignin precursors were detected in developing culms by liquid chromatography–mass spectrometry. The ferulic acid content decreased from May to June, indicating that ferulic acid was utilized in early stages of cell wall formation. Monolignol glucosides were detected at early stages of lignification, whereas the contents of monolignols, coniferaldehyde, sinapaldehyde, p-coumaric acid, and ferulic acid peaked at later stages of lignification. Therefore, lignin precursors may be supplied differentially during the lignification process. In August, the rate of lignification decreased, although the contents of various lignin precursors peaked, implying that the rate-limiting step in the cessation of lignification in bamboo is transport or polymerization of lignin precursors, rather than their biosynthesis.  相似文献   

4.
To clarify the behavior of whole lignins in wood cell walls during alkaline nitrobenzene oxidation, the delignification process from cell walls in normal and compression woods of Chamaecyparis obtusa Endl. (Cupressaceae) was observed using ultraviolet and transmission electron microscopies. The lignin content conspicuously decreased to around 10% after 35min in normal wood. The lignin content in compression wood finally leveled off at aroumd 10% after 50min. In gel filtration of oxidation products in ethyl acetate, a high molecular weight fraction was prominent in extracts from the early stage of the reaction. As the oxidation progressed, the high molecular weight fraction became less prominent in both normal and compression wood. Changes in the weights of cell wall residues during reaction indicated that approximately half of the components other than lignin were also removed from the cell walls. This shows that the majority of lignin with relatively high molecular weight is removed from the cell walls together with polysaccharides in the early stage of the reaction and that further oxidative degradation occurs in solution in later stages. Only a small amount of the lignin with low molecular weight could be analyzed by gas chromatography.Parts of this report were presented at the 47th (Kochi, April 1997) and 48th (Shizuoka, April 1998) Annual Meetings of the Japan Wood Research Society, and at the Lignin Symposium, Sapporo, October 1997  相似文献   

5.
Lignin is an integral component of the cell wall of vascular plants. The mechanism of supply of lignin precursors from the cytosol into the cell wall of differentiating xylem has not yet been elucidated. The present study showed that a certain amount of coniferyl alcohol glucoside (coniferin) occurred in the differentiating xylem of Japanese cypress (Chamaecyparis obtusa), as previously reported in gymnosperms. Coniferin content peaked in the early stages of secondary wall formation and decreased during lignification. In contrast to gymnosperms, coniferin content was limited in the differentiating xylem of poplar (Populus sieboldii × Populus grandidentata). Moreover, coniferyl alcohol was not detected in all specimens. In the differentiating xylem of poplar, a higher amount of sinapyl alcohol occurred than glucoside (syringin). However, the phloem contained syringin and not sinapyl alcohol. The sinapyl alcohol content in the xylem peaked in the cells with ceasing cell wall formation, and decreased gradually towards the boundary of the annual ring, where the lignin content kept increasing. Sinapyl alcohol in the differentiating xylem of poplar may be used for the lignification of the xylem.  相似文献   

6.
Summary A sieving technique has been developed for the separation of middle-lamella fragments. The middle-lamella fraction as well as the whole wood and compression wood from Picea abies have been analysed by nitrobenzene oxidation and acidolysis in order to determine the content of p-hydroxyphenylpropane units in the middle-lamella lignin. These analyses revealed only traces of p-hydroxyphenylpropane units in the whole wood and in the middle-lamella fraction but considerable amounts were found in compression-wood lignin. This points to the fact that middle-lamella lignin is of guaiacyl nature and that earlier results reporting high proportions of p-hydroxyphenylpropane units in the middle lamella-lignin may be due to the inclusion of compression wood in the fraction studied. The acidolysis experiments further indicate that the middle-lamella lignin has fewer uncondensed -0-4 aryl ether structures than the whole wood lignin.The skilful technical assistance of Mrs. Britta Samuelsson and Mr. Johan Lindberg is highly appreciated. The author also thanks Dr. Knut Lundquist for supplying some of the reference compounds, and Dr. Hanne-Lise Hardell for help with the microscopic pictures  相似文献   

7.
Summary Lignin distribution in developing tracheids of Pinus radiata was studied throughout the growth' season using quantitative interference microscopy. The pattern of lignification remained constant although the number of lignifying cells varied reaching a maximum in summer. Lignification of the secondary wall of latewood tracheids was incomplete at the onset of winter. Each stage of lignification was preceded by deposition of carbohydrates with lignification of the middle lamella starting after S1 formation and lignification of the secondary wall starting after S3 formation. Lignification of the middle lamella was completed before the start of lignin deposition in the secondary wall. In one of the trees examined, the secondary wall lignified concurrently with the middle lamella and this was associated with a low lignin concentration in the middle lamella of mature cells. The secondary wall reached a mature lignin concentration of 21–22% v/v except in one specimen containing severe compression wood which reached 28% v/v. The cell corner middle lamella reached a mature lignin concentration of 74–87% v/v.  相似文献   

8.
The present study is focused on analysing the suitability of different Streptomyces strains for biomechanical pulping purposes using spruce wood (Picea abies) as substrate. After 2 weeks of incubation, no apparent variations in lignin Klason content of treated woods were detected compared with the control. However, the increase in acid-soluble lignin fraction pointed out chemical alterations in lignin moiety. Through Py-GC/MS analysis enrichment in cellulose and lignin molecule modifications were detected in treated woods. The increase in the relative abundance of the most G-type phenol units with a higher oxidation degree suggests that some oxidation occurred in the lignin C3-alkyl chain. In addition, the decrease in the phenylmethane + phenylethane/phenylpropane (phC1 + ph C2/ph C3) ratio would indicate the ability of Streptomyces strains to breakdown the C3-alkyl chain linkages once carbons had been oxidized. From this study it could be concluded that the assayed strains are able to produce a delignification of spruce wood which may improve mechanical pulping processes.  相似文献   

9.
The moisture diffusion coefficient of compression wood in spruce (P. abies) and tension wood in beech (F. sylvatica) was examined. The results indicated that the diffusion coefficient measured under steady-state condition (cup method) could well characterize the drying kinetics of the reaction woods. The compression wood offered more resistance to the moisture diffusivity when compared with the corresponding normal wood. The thick cell wall rich in lignin explains the small mass diffusivity in compression wood. In contrast, the mass diffusivity in beech is almost always higher in tension wood than in normal wood, in spite of similar density values. The high moisture diffusion in tension wood can be explained by the ease of bound water diffusion in the gelatinous layers (G-layers).  相似文献   

10.
The factors that cause weather-induced deterioration of wood surfaces were determined by chemical and spectroscopic analyses. Albizzia (Paraserianthes falcata Becker.) and sugi (Cryptomeria japonica D. Don) were exposed to two temperate conditions of natural weathering with and without rainfall and to accelerated conditions of artificial weathering coupled with ultraviolet (UV) light irradiation and water flashing. Infrared spectroscopic analysis showed that the oxidative reaction of lignin was observed under all conditions of weathering for both wood species. However, a marked decrease in lignin and hemicellulose content were recognized when albizzia woods were exposed to weathering with water. Lignin content in the softwood sugi did not decrease as much as in albizzia even in the presence of water, but the modification of lignin macromolecules was assumed to be accelerated by water, as seen by electron spin resonance spectroscopy. These results showed that the presence of water promotes the weathering deterioration of wood under UV irradiation.  相似文献   

11.
Summary To elucidate biochemical features leading to p-hydroxyphenyl-rich lignin in gymnosperm reaction wood the activities of the following five enzymes involved in the biosynthesis of p-hydroxyphenyl lignin were compared in reaction and opposite woods: phenylalanine ammonialyase (EC 4.3.1.5), cinnamate 4-hydroxylase (EC 1.14.13.11), p-hydroxycinnamate: CoA ligase (EC 6.2.1.12), cinnamyl alcohol dehydrogenase (EC 1.1.1.-) and peroxidase (EC 1.11.1.7). The enzyme activities in the reaction woods of Thuja orientalis and Metasequoia glyptostroboides were remarkably higher than those in the opposite woods, reflecting the higher contents of p-hydroxyphenyl lignin in reaction wood.This work was partly supported by the Grant-in-Aid for Scientific Research (548047) from the Ministry of Education, Science and Culture of Japan. We thank the Ministry of Education for the support  相似文献   

12.
Summary Anatomical differences in xylem between the upper and lower sides formed in the inclined stems of Buxus microphylla with different angular displacement from the vertical were examined microscopically. B. microphylla exhibited a pronounced growth promotion on the lower side of the inclined stems. Formation of tension wood (gelatinous fibers) was not observed. Xylem formed on the lower side showed some interesting features resembling the compression wood formed in gymnosperms. The reaction wood tracheids and vessels showed an excessive lignification in their secondary walls but lacked both helical cavities and an S3 layer, features that were almost the same as those of primitive gymnosperms. These results indicate that B. microphylla has an ability to form compression wood, suggesting that in the genus Buxus a different mechanism in the conducting elements was developed in the phylogenetic evolution.The first author would like to express his sincere thanks to Dr. T. E. Timell, College of Environmental Science and Forestry, State University of New York, Syracuse, New York, for his invaluable suggestions in connection with this research  相似文献   

13.
Wood samples of apitong (Dipterocarpus grandiflorua) and ilang-ilang (Ilang-Ilang C. dadloyi) and feces of termites [Cryptotermes brevis (Walker)] fed on these woods were collected from University of the Philippines, Los Baňos. Lignin of each sample was isolated by Björkman’s procedure. There was no significant difference in 1H nuclear magnetic resonance (NMR) spectra or in the methoxyl content between Björkman lignins from original woods and termite feces. Differences were detected in the contents of aliphatic and unconjugated phenolic hydroxyl groups, suggesting minor structural changes of lignin during digestion by termites. In addition, the ratio of syringyl to guaiacyl nuclei of Björkman lignin from termite feces determined by 1H NMR spectra was higher than those from the original woods. The molar ratio of syringyl to guaiacyl nuclei of termite feces was higher than those from the original woods as determined by alkaline nitrobenzene oxidation. These results suggest that the structural changes of lignin in the termite gut are due to the insignificant formation of C-C linkages in guaiacyl nuclei. It was concluded that there were minor changes in the structural features of lignin under mostly anaerobic conditions, in contrast to the significant changes that occur through biological modification under aerobic conditions.  相似文献   

14.
Many products and abundant wastes from tropical plantations, such as latex, palm oil, and coconut production due to replantation, are waiting effective utilization. Nonutilized tropical biomass — oil palm (Elaeis guneensis Jacq.), coconut (Cocos nucifera L.) coir dust and coir fiber, and rubber (Hevea brasiliensis) wood — were analyzed for chemical and structural characteristics of wall polysaccharides and lignin. Coconut coir dust is mostly composed of middle lamella and is separated from coir fiber, which is composed of secondary walls. These were supported by lignin content, and structural characteristics of wall polysaccharides and lignin. The chemical and spectroscopic characteristics of walls of rubber xylem were similar to those of typical temperate angiosperm woods. Oil palm frond was significantly rich in arabinoxylan, and numerous acetyl groups were substituted to the arabinoxylan. Lignin of oil palm frond and wall polysaccharides of coconut coir dust are substituted with hydroxybenzoic acids with ester and ether linkages. Some p-hydroxybenzoic acid substituted to the wall polymers of coconut coir dust would contribute to the formation of associations between polysaccharides and lignin. Based on the above results it is suggested that coconut coir fiber and rubber wood are suitable resources for chemical pulp production for paper-making, but oil palm frond is not.  相似文献   

15.
The behaviour of longitudinal shrinkage was investigated in the corewood of a swept, 17-year-old New Zealand radiata pine stem. Wood categories in terms of normal wood, mild compression wood and severe compression wood were identified microscopically using autofluorescence of lignin. Average longitudinal shrinkage was collated according to corewood location and wood category within corewood in the leaning and the vertical parts of the stem, and then maximum radial difference of longitudinal shrinkage within growth ring was examined. The results show that the average longitudinal shrinkage is significant (2.4%) in the corewood of the leaning part of the stem. Among wood categories, severer compression wood displays the highest (2.9%) average longitudinal shrinkage. In the context of this study, growth rings may consist of one of three types of wood: (1) only normal wood; (2) a single compression wood type; and (3) mixed-type wood. Where multiple compression woods co-existed with normal wood, the maximum radial difference of longitudinal shrinkage within the growth ring was found to be 4.0%. A strong correlation (R 2 = 0.90) between average MFA and average longitudinal shrinkage suggests a significant influence of the average MFA on average longitudinal shrinkage across the three growth ring types.  相似文献   

16.
Summary Opposite wood, normal side wood, and compression wood were isolated from leaning stems of Abies balsamea, Larix laricina, Picea mariana, Pinus resinosa, and Tsuga canadensis and were subjected to analyses for lignin and relative carbohydrate composition. There were no statistically significant differences between the data obtained for opposite wood and side wood. Contrary to some earlier reports, opposite wood has exactly the same content of lignin, cellulose, and hemicelluloses as has corresponding normal wood.This paper is dedicated to Dean Edwin C. Jahn in honor of his 70th birthday.  相似文献   

17.
Summary The distribution of lignin in normal and compression wood of loblolly pine (Pinus taeda L.) has been studied by the technique of lignin skeletonizing. Hydrolysis of the wood carbohydrates with hydrofluoric acid left normal wood tracheids with a uniform distribution of lignin in the S1 and S2 cell wall layers. However, the S3 region of both earlywood and latewood tracheids consistently retained a dense network of unhydrolyzable material throughout, perhaps lignin.Lignin content in compression wood averaged about 7% more than in normal wood and appears to be concentrated in the outer zone of the S2 layer. The inner S2 region, despite helical checking, is also heavily lignified. The S1 layer, although thicker than normal in compression wood tracheids, contains relatively little lignin.Ray cells, at least in normal wood, appear to be lignified to the same extent, if not more so in certain cases, than the longitudinal tracheids. Other locations where lignin may be concentrated include initial pit border regions and the membranes of bordered pits.This report is a detailed excerpt from the Ph. D. dissertation of R. A. P. Financial support provided by the College of Forestry at Syracuse University and the National Defense Education Act is hereby gratefully acknowledged.  相似文献   

18.
This study aims to evaluate the chemical composition of wood and extractives of Pinus taeda and Schizolobium parahyba (guapuruvu) as potential feedstock for new applications in the biorefinery industry. For this purpose, their content of α-cellulose, hemicellulose, insoluble lignin, hot water solubility, NaOH1% solubility, inorganic materials (ash), and monomeric sugars by high-performance liquid chromatography was quantified. Attenuated total reflectance infrared spectroscopy and thermogravimetric analysis were also used to complete the physicochemical characterization of the studied woods. The extractives were obtained by soxhlet extraction with ethanol:toluene and dichloromethane and identified with pyrolysis-gas chromatography/mass spectroscopy technique. The results showed that guapuruvu wood has the higher amount of hemicellulose (16%) when compared to pine wood (10%), which resulted in higher solubility in alkali solution. Furthermore, in relation to other biomasses, the two woods presented more percentage of lignin and minor content of hemicelluloses. The P. taeda wood presented the highest percentage of extractives mainly composed of fatty acids and aromatic hydrocarbons, while guapuruvu wood had a higher percentage of phenolic compounds and also fatty acids. Both the materials have low content of extractives with dichloromethane and were mainly composed of lipophilic compounds.  相似文献   

19.
Summary This electron microscopy study is concerned with the dormant cambial cells in compression wood of Picea abies (L.) Karst. The cambial zone comprised 4–8 rows of fusiform cells. Each radial file contained the group known as Sanio's four, namely an initial, a mother, and two daughter cells. Groups of three, resulting from a failure of a mother or a daughter cell to divide, were also present. Undifferentiated xylem tissue cells occurred singly, in pairs, or in groups of four. These cells and the last-formed tracheids were often enclosed by a common primary wall. The fusiform cells had a large, elongated nucleus, numerous small vacuoles, and a frequently infolded plasma membrane. Golgi apparatus and endoplasmic reticulum were rare, while plastids, amyloplasts, and lipid droplets were common. Cambial ray cells contained much lipid material. The tissues were similar to cambial tissues in normal wood of conifers. The present results can only be interpreted in terms of the single layer of initials and sequence of cell divisions established by Sanio. The initial can be located by several criteria in dormant and active cambial regions in conifers. It could be shown that the existence of the group of Sanio's four is better documented in the literature than has so far been recognized. The occurrence of a variable number of primary cell walls is discussed with reference to the concentration of lignin in the middle lamella of mature xylem.  相似文献   

20.
In vitro wood slats degradation assays reveal that both the white root rot fungus R. lignosus and the brown root rot fungus P. noxius cause a white rot of wood. In vivo (infected tap roots) they cause the same type of decay. Nevertheless lignin determination show the rubber-tree ability to react against the parasite aggression by increased lignification of tissues.  相似文献   

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