Showing papers in "Iawa Journal in 2012"
TL;DR: The principal component analyses revealed a strong influence of tree morphology and a weaker influence of climate on the hydraulic stem architecture and in contrast the general climatic site conditions strongly influenced fibre and parenchyma tissue.
Abstract: For a better understanding of the influence of external growth factors on the wood structure, samples of 139 tropical trees were analysed across plant families and a wide climatic gradient. For all samples a unique data set on climate, site and forest stand conditions is available. Different vessel variables as well as the relative cross-sectional area of vessel, parenchyma and fibre tissue were studied in individual tree rings of varying sizes. High within-species and within-site variation of wood anatomical variables was observed which was higher than inter-species and -site variation. In addition, between-ring variation within many individuals was higher than variation between individuals. The differences within individuals show how trees can adapt or adjust to environmental variability and can provide information about the plasticity of a species under changing environmental conditions. The variable ‘vessel diameter’ showed the strongest and most significant correlations to other wood anatomical variables, but also to climate parameters and tree morphology. Thereby tree size (DBH & height) and crown exposure to light had the strongest impact on vessel size and consequently on hydraulic stem architecture. General climate conditions only showed a weak influence on vessel variables. The principal component analyses revealed a strong influence of tree morphology and a weaker influence of climate on the hydraulic stem architecture. In contrast the general climatic site conditions strongly influenced fibre and parenchyma tissue.
87 citations
TL;DR: The present study supports the identification of charred woods, hopefully contributing to the control of charcoal production, and to palaeoenvironmental and archaeobotanical studies.
Abstract: Summary Brazil is the world’s largest producer of charcoal and a great part of this material still comes from native forests – especially from the cerrado biome, which is highly impacted by anthropogenic degradation. The need to control charcoal production increases the demand of charcoal identifi cation, but there is little information about the anatomical modifications due to carbonization. In this paper, fresh and charred wood samples from five Brazilian species were analyzed (Dalbergia violacea , Stryphnodendron polyphyllum, Tapirira guianensis, Vochysia tucanorum, and Pouteria torta). anatomical characters were described and measurements of the main anatomical features of wood and charcoal were statistically compared. Minor modifications were observed: reduction of tangential vessel diameter was the most evident change after carbonization; shrinkage of rays (in width) occurred only in some individuals. The present study supports the identification of charred woods, hopefully contributing to the control of charcoal production, and to palaeoenvironmental and archaeobotanical studies.
39 citations
TL;DR: The optimized radial position for DNA extraction in the stem was demonstrated based on anatomical observation and was greater than that from the heartwood (derived mainly from amyloplasts), and the quantity of DNA decreased by more than 50%.
Abstract: DNA was isolated from the sapwood, transition wood and heartwood of fresh and dried Cunninghamia lanceolata wood using two DNA extraction protocols: the modified CTAB method and the modified Qiagen kit. Our major objective was to (i) determine an optimized method for retrieving good quality and sufficient quantity of DNA from wood, and to (ii) investigate the effect of different radial positions of fresh and dried wood for DNA extraction. In comparison with the modified CTAB method, a greater quantity of higher quality DNA – both chloroplast and nuclear ribosomal DNA – was retrieved using the Qiagen kit protocol. The chloroplast DNA regions retrieved from both fresh and dried wood were successfully amplified using both protocols, but the PCR amplification for the rDNA-ITS region from the heartwood failed using both protocols. The quantity and purity of the DNA from the sapwood and transition wood (derived from nuclei and plastids in the parenchyma cells) was greater than that from the heartwood (derived mainly from amyloplasts). Due to the influence of the drying treatment, the quantity of DNA decreased by more than 50%. The optimized radial position for DNA extraction in the stem was demonstrated based on anatomical observation.
28 citations
TL;DR: In this paper, the three methods: a threshold density of 480 kg/m3, the inflection point method and Mork's index were used to define the point at which earlywood transitioned to latewood using annual rings for 20 loblolly pine breast height increment cores.
Abstract: Demarcating the transition from earlywood (EW) to latewood (LW) is important for accurately estimating the width of both wood types within an annual ring, their respective densities and the proportion of LW within an annual ring. Different methods have been used to define the transition from EW to LW and include Mork’s index, the threshold density method and the inflection point method. In loblolly pine (Pinus taeda L.) a threshold value of 480 kg/m3 (basic density) has conventionally been used to demarcate EW from LW. In this study the three methods: a threshold density of 480 kg/m3, the inflection point method and Mork’s index were used to define the point at which EW transitioned to LW using annual rings for 20 loblolly pine breast height increment cores. Significant correlation was observed among the three methods in identifying the demarcation point. However, the results indicated that EW-LW demarcation points identified using the three methods in juvenile wood rings were different to mature wood rings; with the most pronounced differences being observed for Mork’s index.
27 citations
TL;DR: The Chenopodiaceae often grow in extreme habitats, and this is reflected by their wood anatomy, and among the annual species, halophytes have narrower vessels than xeric species of steppes and prairies, and than species of nitrophile ruderal sites.
Abstract: The wood anatomy of the Chenopodiaceae is distinctive and fairly uniform. The secondary xylem is characterised by relatively narrow vessels (<100 μm) with mostly minute pits (<4 μm), and extremely narrow vessels (<10 μm intergrading with vascular tracheids in addition to “normal” vessels), short vessel elements (<270 μm), successive cambia, included phloem, thick-walled or very thick-walled fibres, which are short (<470 μm), and abundant calcium oxalate crystals. Rays are mainly observed in the tribes Atripliceae, Beteae, Camphorosmeae, Chenopodieae, Hablitzieae and Salsoleae, while many Chenopodiaceae are rayless. The Chenopodiaceae differ from the more tropical and subtropical Amaranthaceae s.str. especially in their shorter libriform fibres and narrower vessels. Contrary to the accepted view that the subfamily Polycnemoideae lacks anomalous thickening, we found irregular successive cambia and included phloem. They are limited to long-lived roots and stem borne roots of perennials (Nitrophila mohavensis) and to a hemicryptophyte (Polycnemum fontanesii). The Chenopodiaceae often grow in extreme habitats, and this is reflected by their wood anatomy. Among the annual species, halophytes have narrower vessels than xeric species of steppes and prairies, and than species of nitrophile ruderal sites.
25 citations
TL;DR: The radial variation in the cell morphology and wood properties showed an almost identical pattern in the three categories, suggesting that xylem maturation depends on the cambial age rather than growth rate.
Abstract: In view of the importance of long-rotation plantation forestry in SE Asia to limit soil erosion, the cell morphology and wood properties of 35-yearold plantation trees of yellow meranti, Shorea acuminatissima Sym. were studied. To understand the effects of growth rate on cell morphology and wood properties, 131 trees in a stand were classified according to their stem diameter as fast-, medium-, and slow-growing. Five trees in each category were selected for determining the cell morphology and wood properties. There were significant differences in vessel diameter, vessel frequency, and cell wall thickness of wood fibers in the three categories. The fast-growing trees had a relatively low frequency of wide vessels and thick-walled wood fibers. However, no significant differences in basic density or compressive strength parallel to grain were identified in the three categories. The radial variation in the cell morphology and wood properties showed an almost identical pattern in the three categories, suggesting that xylem maturation depends on the cambial age rather than growth rate.
25 citations
TL;DR: This exploratory study on Scots pine in subarctic Finland was aimed at identifying the climatic signal(s) ‘archived’ in cellular anatomy and tree-ring variables, such as diameter and wall thickness of tracheids, or early- and latewood width, respectively, and these variables turned out to significantly reflect other climatic signals than the tree-rings did.
Abstract: This exploratory study on Scots pine in subarctic Finland was aimed at identifying the climatic signal(s) ‘archived’ in cellular anatomy and tree-ring variables, such as diameter and wall thickness of tracheids, or early- and latewood width, respectively. For this purpose, these variables were measured in increment cores year by year from 1961–2008 and compared to each other. According to the low values of some statistical descriptors (e.g., expressed population signal and mean sensitivity) the cell-anatomical variables could, in fact, not be expected to be useful climatic proxies. Nevertheless, they turned out to significantly reflect other climatic signals than the tree-ring variables did. The tree-ring variables responded positively to temperature in July and August, whereas the cell-anatomical variables responded positively to temperature in December and January, prior to the growing season. These encouraging findings provide a strong rationale for further studies, and for enlarging the statistical sample size.
24 citations
TL;DR: Wood anatomy and technological features support the profitable use of P. azorica for the furniture industry instead of biomass production and might be reconsidered and its properties emphasized to combat the species’ decline and to encourage the restoration of its habitat.
Abstract: Picconia azorica (Tutin) Knobl. is an Azorean endemic species of the Oleaceae, exploited over centuries and recently classified as endangered. It suffers from reduction and fragmentation of its habitat, and from competition with exotic species. Wood anatomy was examined and compared with Picconia excelsa, enhancing our knowledge about the genus Picconia which contains only these two species. Macroscopic and technological characterizations by colour, pH, wood density, compression and bending strengths, shrinkages, static quality factor, ash content and Higher Heating Value were investigated and compared with other Oleaceae and other hardwoods. At the anatomical level, P. azorica does not differ from P. excelsa, except for the number of vessels and rays per mm2 and the ray type. The technological features support the profitable use of P. azorica for the furniture industry instead of biomass production. Because of its valuable wood, P. azorica might be reconsidered and its properties emphasized to combat the species’ decline and to encourage the restoration of its habitat.
13 citations
TL;DR: In this paper, the authors evaluated the growth of four gymnosperm tree species growing in seven catchments in the Indus Basin of the Karakorum range, North Pakistan, using two versions of tree-ring chronologies: "standard" and "residual" chronologies.
Abstract: The climate/growth relationships of four gymnosperm tree species growing in seven catchments in the Indus Basin of the Karakorum range, North Pakistan, were evaluated for using two versions of tree-ring chronologies: “standard” and “residual” chronology. The growth of the trees was compared to instrumental climate records registered in Gilgit and to a climate data set of a 0.5° latitude-longitude grid. The effect of the previous year’s tree-ring widths on growth resulted in a higher correlation in the case of “standard” chronologies. A consistently significant response to climate was observed for all species at all sites. Such results highlight the potential for a multi-species approach for climate reconstructions. Of all the four species assessed, the strongest climate signal was seen in Pinus gerardiana. Winter and spring precipitation showed a pronounced positive correlation with tree growth while an inverse response to spring temperature was seen. Of the two climate parameters (temperature and precipitation) the strongest response was seen to rainfall. The gridded and the instrumental climatic data produced similar correlation patterns but the highest values were obtained with the “local” Gilgit data although some tree-ring sites are about 90 km apart from this meteorological station. Overall, the results demonstrate a high potential of the trees of the study region for reconstructing of past climate and past river flow.
13 citations
TL;DR: In this paper, the influence of extractives, lignin and holocellulose contents on performance index (PI) of seven woods used or tested for violin bows was investigated.
Abstract: In this paper we investigate the influence of extractives, lignin and holocellulose contents on performance index (PI) of seven woods used or tested for violin bows. Woods with higher values of this index (PI = √MOE/ρ, where MOE is modulus of elasticity and ρ is density) have a higher bending stiffness at a given mass, which can be related to bow wood quality. Extractive content was negatively correlated with PI in Caesalpinia echinata, Handroanthus sp. and Astronium lecointei. In C. echinata holocellulose was positively correlated with PI. These results need to be further explored with more samples and by testing additional wood properties. Although the chemical constituents could provide an indication of quality, it is not possible to establish appropriate woods for bows solely by examining their chemical constituents.
12 citations
TL;DR: In this paper, the orientation of cellulose microfibrils in the S2 and G-layer of Populus nigra branches was determined by a combination of transmission electron microscopy (TEM) imaging and image analysis.
Abstract: Tension wood of poplar (Populus nigra) branches was studied by lightand electron microscopy. The characteristic features of tension wood such as wider growth rings, reduced vessel density and higher gross density were confirmed by our results. Based on a novel combination of transmission electron microscopy (TEM) imaging and image analysis, involving Fourier transformation, the orientation of cellulose microfibrils in the S2- and G-layer was determined. Within the G-layer microfibril angle (MFA) was parallel to the growth axis (0°). However, in the S2 it was 13° in tension wood fibres and 4° in normal wood fibres. With the exception of the relatively low fibril angle in the S2 of tension wood fibres (13°) the results are in good agreement with those of the literature.
TL;DR: The wide variation in climber wood structure compared to the relatively conservative anatomy of the subshrubs is illustrated, illustrating the high need for mechanical self-support and an elevated need for hydraulic con- ductance to enable longer-distance water transport.
Abstract: SUMMARY Climbers and self-supporting woody plants have different constraints on their stems. Although plants of both growth forms need wood that functions mechanically and hydraulically, climbers have a lower need for mechanical self-support and an elevated need for hydraulic con- ductance to enable longer-distance water transport. We sampled all the woody climbers (10 species) and most of the woody subshrubs (25 spe- cies) of the island of Cyprus in the eastern part of the Mediterranean, to FKDUDFWHUL)HWKHLUYHVVHODQG�?EHUDQDWRPLHVUHODWLYHWRK\GUDXOLFDQG� mechanical function. Consistent with their lower need for self-support, on average the climbers had lower wood density than did the subshrubs (0.44 g/cm3 ± 0.15 vs. 0.59 g/cm3 ± 0.20, means ± s.d.) and had a lower 15). Consistent with climbers' need for higher hydraulic conductance and total plant height, climbers had vessel sizes and frequencies closer to the theoretical packing limit than did subshrubs. Lastly, we grouped species within a growth form by site water availability (dry vs. wet site), site tem- perature (cold vs. hot site), site water equability (low vs. high), and xylem ring porosity (ring porous, semi-ring porous or diffuse porous). Climb- ers had different vessel lumen diameters or vessel frequencies for six of these eight groupings, whereas subshrubs showed no such differences, illustrating the wide variation in climber wood structure compared to the relatively conservative anatomy of the subshrubs.
TL;DR: In this paper, the wood anatomy of Cneorum tricoccon with its semi-ring porosity, dendritic vessel pattern, vascular tracheids and helical vessel wall thickenings is described for the first time in detail.
Abstract: Subfamily Spathelioideae of Rutaceae constitutes a well-supported early branching clade of eight small woody genera that were formerly assigned to five different Sapindalean/Rutalean families. This study brings together detailed wood anatomical information on all eight genera (for four the wood anatomy is described for the first time in detail). Wood anatomy strongly supports the inclusion of all Spathelioid genera in Rutaceae and underpins the molecular phylogeny with a set of interesting apomorphies at different nodes of the cladogram. The wood anatomy of Cneorum tricoccon with its semi-ring porosity, dendritic vessel pattern, vascular tracheids and helical vessel wall thickenings stands out in Spathelioideae. This wood anatomical syndrome is hypothesized to be due to adaptive evolution for hydraulic safety and efficiency of this species in a typical Mediterranean climate, where similar syndromes have evolved in many unrelated clades of woody dicots. In at least six unrelated genera of Rutaceae outside Spathelioideae from Mediterranean or cool temperate and montane climates, the syndrome has also evolved in presumably parallel, adaptive evolution.
TL;DR: The overall results may provide opportunities to better understand the quality of small-dimension timber of brutia pine and to better utilise it.
Abstract: Brutia pine (Pinus brutia Ten.) reforestations have been successfully used for decades in restoration of degraded forest ecosystems in Greece. The future purpose of these reforestations might expand to include wood utilisation. This study provides information on tracheid length of juvenile brutia pine aged 14–22 years grown on good and medium sites in Northeastern Greece. In addition, relationships among ring width, latewood proportion, wood density, and tracheid length were evaluated by using Causal Correlation Analysis. Similar mean tracheid length values were found for good and medium sites. Radial variability of tracheid length was similar on the good and medium sites, showing the typical increase in the juvenile phase. On both site types, latewood proportion showed a strong and positive relationship with wood density. Unexpectedly and only on the good sites, a significant positive relationship was found between ring width and wood density. On the medium sites, tracheid length was negatively related to fast growth and positively to high wood density. Tracheid length on the good sites was correlated only with latewood proportion with a weak positive relationship. The overall results may provide opportunities to better understand the quality of small-dimension timber of brutia pine and to better utilise it.
TL;DR: Findings indicate that P. chaquensis causes a mottled pattern of decay (selective delignification plus simultaneous decay) in S. haenkeana wood, causing a whiterot type of decay.
Abstract: Schinopsis haenkeana is a native tree to the Chaco Serrano Forests in Argentina. The white-rot fungus Phellinus chaquensis degrades its wood, causing a whiterot type of decay. The objective of this study was to investigate the structural alterations caused by P. chaquensis in S. hankeana decayed naturally and in vitro. Sound living branches with decay and basidiocarps of P. chaquensis were sampled from the field and in vitro decay tests were performed according to the ASTM D-2017-81 standard method. Naturally decayed branches exhibited an innermost discolored zone with white-rot decay and an outer yellowish-white portion of sound sapwood. Using LM and SEM, degraded tissue displayed diagnostic characters of selective delignification and simultaneous decay. Findings indicate that P. chaquensis causes a mottled pattern of decay (selective delignification plus simultaneous decay) in S. haenkeana wood. Other features such as accumulation of extractives, profuse deposition of crystals and tyloses, typical ofSchinopsis spp. heartwood, were additionally observed. In laboratory degraded material, signs of selective delignification and incipient stages of simultaneous decay were noticeable only microscopically. Chemical analysis revealed an oxidative alteration of aromatic moieties in naturally decayed samples which might be related to the accumulation of phenols as a response to fungal attack when compared to sound samples. Naturally degraded sapwood exhibits anatomical and chemical modifications that indicate the development of discolored wood derived from the host-pathogen interaction.
TL;DR: The overall analysis suggests that R. californica has evolved a strategy of shoot development that allows it to cope with the multiple environmental stresses found in Mediterraneantype ecosystems, among which summer drought and grazing play a major role especially for the survival of seedlings and young plants.
Abstract: Characterisation of anatomical properties and analysis of lignin content and monomer composition were performed on twigs of the shrub Rhamnus californica L. in order to highlight their role in the adaptive strategies of this species in Mediterranean-type ecosystems. Our results showed that R. californica twigs develop a thick cuticle accompanied by several layers of subepidermal cells with suberised walls aiming to save water. The xylem is characterised by anatomical and chemical traits ensuring safety of water transport and preventing permanent damage through the enhancement of mechanical strength, also favoured by the lignification of pith cell walls. Moreover, the accumulation of phenolic compounds in the cortical cylinder is a strategy to protect against herbivory and to screen against high levels of radiation. Our overall analysis suggests that R. californica has evolved a strategy of shoot development that allows it to cope with the multiple environmental stresses found in Mediterraneantype ecosystems, among which summer drought and grazing play a major role especially for the survival of seedlings and young plants.
TL;DR: The hypothesis of pit membrane thickness and composition as a static adaptation to the hydrostatic conditions during vessel differentiation could be refuted and findings point to a more dynamic pit membrane appearance with seasonal changes in thickness and chemical composition.
Abstract: Intervessel pits are prominent wall structures involved in the water transport mechanism of land plants. The role of their intra-tree variation in the regulation of water transport, however, remains enigmatic. The hypothesis was tested that pit membrane thickness and degree of impregnation with phenolic substances increase along the stem axis with increasing tension on the water column as an adaptation to the higher risk for cavitation. Wood samples were taken at different heights from the mangrove tree Rhizophora mucronata growing at Gazi Bay (Kenya). Additional samples were taken along the stem radius to distinguish height from age effect, and from six other mangrove species growing in the same forest. Intervessel pit membranes were studied via transmission and scanning electron microscopy and cellular UV-microspectrophotometry. The hypothesis of pit membrane thickness and composition as a static adaptation to the hydrostatic conditions during vessel differentiation could be refuted. Instead, our findings point to a more dynamic pit membrane appearance with seasonal changes in thickness and chemical composition.
TL;DR: The Wood Ontology project as discussed by the authors provides a structured vocabulary and database resource that will be valuable for all scientists, including the IAWA community to maximizethe utility of the resource and analyses it empowers, it is important for researchers to adopt the use of ontology terms in the collection and dissemination of their data
Abstract: The Wood Ontology project will provide a structured vocabulary and database resource that will be valuable for all scientists, including the IAWA community To maximizethe utility of the resource and analyses it empowers, it is important for researchers to adopt the use of the ontology terms in the collection and dissemination of their data The PO website (wwwplantontologyorg) is the main portal for the Plant Ontology, and presents the current version
TL;DR: A new measurement approach was tested whereby light was directed through disc samples on a flatbed scanner and the deviation along the grain assessed by means of a template to allow the mapping of grain angle variation radially and tangentially within discs.
Abstract: Spiral grain measurements are subject to a high degree of variation and interpretation, depending on the assessment method used. A new measurement approach was tested whereby light was directed through disc samples on a flatbed scanner and the deviation along the grain assessed by means of a template to allow the mapping of grain angle variation radially and tangentially within discs. Initial results showed that the approach was valid for green discs up to 35 mm thick and small enough to fit on an A4 scanner. Comparisons with traditional scribing and cleaving methods were favourable, indicating that the light transmission approach could allow much faster and more accurate data acquisition. The possibility of using larger discs would enhance the ability to assess spatial variation in grain angle and minimise the effects of sample reference geometry with respect to the tree axis (disc tilt and parallax). Further work may also be required to ensure that reliable spiral grain values are obtained from both sapwood and heartwood. The ultimate goal is to develop an automated system for reconstructing stem characteristics from measurements on large fresh green discs to enable the 3-dimensional mapping of individual stem variations in key wood properties and modelling the impacts of silviculture and genetics on wood products.
TL;DR: Investigation of the radial variation of microfibril angle in the S2 layer of the wood fiber wall in P. falcataria revealed that the compression properties of core wood were affected mainly by density, whereas those in outer Wood were affected by both MFA and air-dry density.
Abstract: Paraserianthes falcataria (L.) Nielsen is an important plantation species in Indonesia. The objective of this study was to understand the radial variation of microfibril angle in the S2 layer of the wood fiber wall (MFA) in P. falcataria, and its relationship to compression properties parallel to the grain, including modulus of elasticity (E) and compression strength (σ). MFA gradually decreased from pith to bark while both E and σ increased from pith to bark. Significant differences in MFA, E, and σ were found among the five sample trees. Single-regression analysis of wood and compression properties revealed that the compression properties of core wood were affected mainly by density, whereas those in outer wood were affected by both MFA and air-dry density (AD).
TL;DR: Cheng et al. as discussed by the authors described a new species of Pistacioxylon, PistACioxylon leilaoensis, showing affinities with Pistacia of the Anacardiaceae.
Abstract: SUMMARY A new species of Pistacioxylon, Pistacioxylon leilaoensis Cheng et al., showing affinities with Pistacia of the Anacardiaceae is described from the Miocene of Leilao, Yuanmou Basin, Yunnan Province, southwest China. It provides data for reconstructing the phytogeographic history of Pistacia and the paleoenvironment of the Yuanmou Basin. This fossil suggests a long history of exchange of various taxa including Pistacia between Europe and East Asia during the Tertiary.
TL;DR: Microscopic examination of oltustone reveals that it consists of fossilized Agathoxylon wood (Araucariaceae), which represents one of the latest occurrences of the AraUCariaceae in southern Eurasia and is also the southernmost recorded for the Laurasian continent.
Abstract: Oltustone is a semi-precious gemstone found only in the Late Cretaceous (Upper Maastrichtian) Dutlu Formation of Turkey. Microscopic examination of oltustone reveals that it consists of fossilized Agathoxylon wood (Araucariaceae). This represents one of the latest occurrences of the Araucariaceae in southern Eurasia and is also the southernmost recorded for the Laurasian continent.
TL;DR: Comparisons of the proportions of the constituent cell types in wood from the trunk and branches of original trees with those from regrowth branches after three and six years suggest that the anatomical differences between branch and regrowth are the result of rapid regrowth after coppicing or pollarding.
Abstract: Poincianella pyramidalis (Tul.) L.P. Queiroz (‘catingueira’) is one of the most used trees by rural communities for wood and charcoal in the caatinga of northeast Brazil. It grows rapidly and can survive and thrive after either wet or dry season coppicing or pollarding. This paper explores the anatomical basis for P. pyramidalis being a good choice for fuel and charcoal by comparing the proportions of the constituent cell types (vessels, fibres and parenchyma) in wood from the trunk and branches of original trees with those from regrowth branches after three and six years. Since wood density is correlated with mechanical and physiological strategies of trees, the observations suggest that the anatomical differences between branch and regrowth are the result of rapid regrowth after coppicing or pollarding. The observed differences in cell type proportions along the trunk and branches are of interest from a physiological point of view but have little bearing on whether the regrowth is good for charcoal.
TL;DR: Results show that EgMYB2 is a master regulator controlling the synthesis of the three major polymers of the secondary cell wall and that its overexpression has significant influence on quantitative anatomical traits of wood which affect its functional properties.
Abstract: The transcriptional activator EgMYB2, which belongs to the large R2R3 MYB transcription factor family, plays a major role in the coordinated control of genes in the lignin biosynthetic pathway. Given that lignin genetic modification can lead to xylem alterations compromising vascular functionality, we characterised wood anatomical properties of two transgenic tobacco lines over-expressing EgMYB2, using light, fluorescence, confocal, transmission electron microscopy, immunocytochemical labelling and digital image analysis. Transgenic wood, compared with wild type, was characterised by both reduced frequency of larger vessels and lower vessel grouping; these traits are known to have physiological implications in terms of water transport efficiency and safety against embolism. Transgenic wood also appeared denser due to the occurrence of thicker cell walls and higher incidence of fibres than wild type. Increased lignin content was accompanied by a concomitant increase in cellulose and xylan, but no alterations in the usual distribution of guaiacyl and syringyl units in secondary cell walls were observed. Altogether, these results show that EgMYB2 is a master regulator controlling the synthesis of the three major polymers of the secondary cell wall and that its overexpression has significant influence on quantitative anatomical traits of wood which affect its functional properties.
TL;DR: The affinities of Chadronoxylon florissantensis, the most common angiosperm wood at Florissant, are reevaluated; its combination of features suggests relationships with two families in the Malpighiales, the Salicaceae and Phyllanthaceae.
Abstract: A fossil wood with features similar to those of the Oligocene Hovenia palaeodulcis Suzuki (Rhamnaceae) from Japan is described from the late Eocene Florissant Fossil Beds National Monument, Colorado, USA This is the first report of fossil wood of this Asian genus in North America and is further documentation of Tertiary exchange between East Asia and North America The affinities of Chadronoxylon florissantensis, the most common angiosperm wood at Florissant, are reevaluated; its combination of features suggests relationships with two families in the Malpighiales, the Salicaceae and Phyllanthaceae Chadronoxylon is compared with Paraphyllanthoxylon Bailey The Eocene P hainanensis from China has notable differences from the original diagnosis of Paraphyllanthoxylon, but shares features with Chadronoxylon warranting transfer of P hainanensis to Chadronoxylon and the creation of Chadronoxylon hainanensis (Feng, Yi, Jen) Wheeler & Meyer, comb nov
TL;DR: This note describes and illustrates a rapid and user-friendly method to section fragile charcoals by microtome after applying two component adhesive to the transverse charcoal surface and using adhesive tape to prevent the sections to disintegrate.
Abstract: This note describes and illustrates a rapid and user-friendly method to section fragile charcoals by microtome after applying two component adhesive to the transverse charcoal surface and using adhesive tape to prevent the sections to disintegrate.
TL;DR: The wood structure of two related African genera, Cussonia Thunb.
Abstract: The wood structure of two related African genera, Cussonia Thunb. (15 of 21 species) and the monotypic Seemannaralia R.Vig. (Araliaceae) is examined. The considerable diversity in wood anatomical characters within these taxa is mostly related to environmental factors; taxonomic groupings or phylogenetic relationships seem to be less important. The shortening of vessel elements and fibres, an increase in vessel number per group, a decrease in vessel diameter and a reduction in the number of bars of perforation plates, are associated with the more temperat species. The changes in vessel grouping show a significant correlation with rainfall. The placement of the simple-leaved Cussonia species in the subgenus Protocussonia and the isolated position of C. paniculata Eckl. & Zeyh., the only member of the subgenus Paniculatae, are supported. Many Cussonia species share a very low fibre to vessel element length ratio. Despite the basal position of Seemannaralia relative to Cussonia revealed by molecular data (Plunkett et al. 2004), its wood structure is more specialised in terms of the Baileyan major trends in wood evolution. This discrepancy may be the effect of a long-term adaptation of tropical ancestors of Seemannaralia to drier biomes.
TL;DR: The pattern of secondary growth and structure of secondary xylem was studied in the stem of the Neotropical liana Securidaca rivinifolia A. St.-Hil.
Abstract: The pattern of secondary growth and structure of secondary xylem was studied in the stem of the Neotropical liana Securidaca rivinifolia A. St.-Hil. (Polygalaceae). Increase in thickness of the stem was achieved by formation of successive cambia, from which initially two or three successive rings formed complete oval to circular cambia. Thereafter, the successive cambia were always crescent-shaped and never formed a complete cylinder, resulting in dumbbell-shaped cross-sectional outlines of the stems. The first successive cambium originated in the pericyclic parenchyma located outside the crushed protophloem. Prior to the development of cambium, pericyclic parenchyma formed a meristematic band of radially arranged cells. From this band, cells located in the middle of the band became the new ring of cambium. Cells on the inner face of the xylem produced by newly formed cambium differentiated into conjunctive tissue. The first elements to be differentiated from the newly developed cambium were always xylem fibres but differentiation of vessels was also observed occasionally. The xylem was diffuse porous with relatively distinct growth rings and composed of mostly solitary vessels with simple perforation plates, fibres with bordered pits, paratracheal axial parenchyma, and exclusively uniseriate rays.
TL;DR: A user-friendly and rapid technique is described and illustrated to produce high-quality sections of small plant stems, such as those of Arabidopsis, without embedding.
Abstract: A user-friendly and rapid technique is described and illustrated to produce high-quality sections of small plant stems, such as those of Arabidopsis, without embedding.
TL;DR: Observations of the perennial leaves indicate that torus-bearing, pitted tracheary elements extend throughout the vasculature of the organ including the veins delimiting the areoles and the vein termini.
Abstract: Osmanthus armatus Diels is a member of the Oleaceae whose woody branches were previously found to possess torus-bearing pit membranes. Observations of the perennial leaves indicate that torus-bearing, pitted tracheary elements extend throughout the vasculature of the organ including the veins delimiting the areoles and the vein termini. Torusbearing tracheary elements differentiate into the vein termini but do not develop at the very ends. Rather, the distal ends of vein termini consist of tracheids without tori and of phloem containing intermediary cells. The latter cell type is a component of the phloem in the small diameter leaf veins. Tori are considered to be xeromorphic features which, along with a thick cuticle and sclereids, are advantageous for the perennial growth habit of the leaves.