Vascular Tracheids Research Articles

The role of imperforate tracheary elements and narrow vessels in wood capacitance of angiosperm trees

Summary There is a broad diversity of imperforate tracheary elements (ITEs) — libriform fibers, fiber-tracheids, true tracheids and vasicentric/vascular tracheids — described thoroughly by Sherwin Carlquist. However, in a quantitative sense, the functional meaning of different ITE types present in the wood of vessel-bearing angiosperms remains unclear because very few structure–function studies measure ITEs’ properties. ITEs with abundant pits and wide pit borders — vascular tracheids, vasicentric tracheids, and true tracheids sensu Carlquist — have been shown to conduct water and, thanks to this conductive ability and the multitude of pits, they could also contribute to wood capacitance. A dataset of 30 temperate angiosperm tree species was reanalysed to record the presence/absence of true, vasicentric, and vascular tracheids including data on conduits15 fraction and vessel-conduit15 contact fraction (conduits15 were defined as cells resembling vessels and with a maximum lumen diameter of 15 μm. They encompassed narrow vessels, vasicentric tracheids, and vessel tails). The presence of tracheids, conduits15 fraction, and contact fraction had no effect on wood capacitance, except, per given wood volumetric lumen water content, species with true tracheids tended to have lower capacitance. These results suggest that the presence of tracheids or conduits15 properties do not limit wood capacitance, but the results do not exclude the potential role these cells may play in internal water dynamics.

Charcoalified wood from the cenomanian of gard (Southern France): An insight into early angiosperm palaeoecology

The discovery in the Cenomanian (early Late Cretaceous) of Southern France of several localities with abundant charcoal has brought to light several angiosperm wood types. This is the oldest angiosperm wood assemblage discovered yet for Europe. Here we analyse this assemblage, with emphasis on features recognized to be of particular palaeoecological and climatic significance for the Cainozoic according to earlier studies and comparing the inferred results to those from other independent lines of evidence (sedimentology, palynology, isotopic geochemistry, etc.). Vessel diameter and distribution, perforation plates, abundance of vascular tracheids and of septate fibres, presence of diffuse axial parenchyma perhaps should not be used as palaeoecological proxies for the Cretaceous because they do not seem to clearly correlate with other lines of evidence that indicate warm tropical conditions. The abundance of fibre-tracheids fits with the other sources of data, but our results are probably biased by preservation problems. On the contrary, the occurrence of growth-rings, porosity, vessel density, occurrence of vessel groups, occurrence of vasicentric tracheids and of some paratracheal to vasicentric and banded axial parenchyma correlate well with other palaeoclimate indicators. These results show that these features can be used for palaeoclimatological inferences during the early Late Cretaceous

Xylem vessel‐diameter–shoot‐length scaling: ecological significance of porosity types and other traits

AbstractFlowering plants predominantly conduct water in tubes known as vessels, with vessel diameter playing a crucial role in plant adaptation to climate and reactions to climate change. The importance of vessels makes it essential to understand how and why vessel diameter, plant height, and other ecological factors are interrelated. Although shoot length is by far the main driver of variation in mean vessel diameter across angiosperms, much remains to be understood regarding the factors accounting for the abundant variation around they‐axis in plots of mean species vessel diameter against shoot length. Here, we explore the potential role of porosity types, wood density, leaf phenology, background imperforate tracheary element type, vasicentric tracheids, vascular tracheids, perforation plate type, and successive cambia in causing variation in they‐intercept or slope of the mean species vessel‐diameter– and vessel‐density–shoot‐length associations at the shoot tip and base. We detected numerous cases of ecologically significant variation. For example, latewood vessels of ring porous species scale with a lower slope than earlywood, i.e., latewood vessels are relatively narrow in taller plants. This pattern is likely the result of selection favoring freezing‐induced embolism resistance via narrow vessels. Wood density was negatively associated with vessel diameter, with low wood density plants having wider vessels for a given height. Species with scalariform perforation plates scale with a lower shoot base vessel‐diameter–shoot‐length slope, likely reflecting selection against scalariform plates in wide vessels. In other cases, functional groups scaled similarly. For example, species with successive cambia did not differ from those with conventional single cambia in their mean vessel‐diameter–shoot‐length scaling, rejecting our prediction that species with successive cambia should have narrower vessels for a given shoot length. They did, however, have fewer vessels per unit shoot cross‐sectional area than plants of similar heights, likely because vessels have longer functional lifespans (and therefore are fewer) in species with successive cambia. Our methods illustrate how vessel diameter can be studied taking shoot length into account to detect ecologically important variation and construct theory regarding plant adaptation via the hydraulic system that includes plant size as a vital element.

Anatomía de la madera de Buddleja L. (Buddlejaceae): análisis fenético

El género Buddleja L. comprende cerca de 100 especies de distribución pantropical que varían desde pequeños arbustos hasta árboles de 20 a 30 m de alto y pocas son lianas. En este trabajo se presentan las características anatómicas de la madera de Buddleja con base en el estudio de 41 especies, de ellas se describen anatómicamente diez por primera vez y de 15 se sintetizan sus características de la literatura. Además, los caracteres de la madera de 41 especies del género se analizan a través de un análisis fenético. El género presenta porosidad de anular a difusa, placas de perforación simple, punteaduras intervasculares alternas y engrosamientos helicoidales en elementos de vaso y traqueidas vasculares; fibras libriformes, septadas en algunas especies; parénquima axial escaso o raro; radios heterogéneos tipo IIB y el 35% de las especies contienen cristales prismáticos de diferentes tamaños en las células de los radios. Los resultados del análisis fenético muestran que hay especies idénticas anatómicamente, sin embargo las especies del género forman dos grandes grupos que se distinguen con base en la combinación de caracteres cualitativos y cuantitativos, más otro conjunto de especies que se separan por la presencia de caracteres cualitativos. Finalmente se discuten algunas consideraciones taxonómicas sobre la posición de Buddleja en el orden Scrophulariales.

BdCESA7, BdCESA8, and BdPMT Utility Promoter Constructs for Targeted Expression to Secondary Cell-Wall-Forming Cells of Grasses.

Utility vectors with promoters that confer desired spatial and temporal expression patterns are useful tools for studying gene and cellular function and for industrial applications. To target the expression of DNA sequences of interest to cells forming plant secondary cell walls, which generate most of the vegetative biomass, upstream regulatory sequences of the Brachypodium distachyon lignin biosynthetic gene BdPMT and the cellulose synthase genes BdCESA7 and BdCESA8 were isolated and cloned into binary vectors designed for Agrobacterium-mediated transformation of monocots. Expression patterns were assessed using the β-glucuronidase gene GUSPlus and X-glucuronide staining. All three promoters showed strong expression levels in stem tissue at the base of internodes where cell wall deposition is most active, in both vascular bundle xylem vessels and tracheids, and in interfascicular tissues, with expression less pronounced in developmentally older tissues. In leaves, BdCESA7 and BdCESA8 promoter-driven expression was strongest in leaf veins, leaf margins, and trichomes; relatively weaker and patchy expression was observed in the epidermis. BdPMT promoter-driven expression was similar to the BdCESA promoters expression patterns, including strong expression in trichomes. The intensity and extent of GUS staining varied considerably between transgenic lines, suggesting that positional effects influenced promoter activity. Introducing the BdPMT and BdCESA8 Open Reading Frames into BdPMT and BdCESA8 utility promoter binary vectors, respectively, and transforming those constructs into Brachypodium pmt and cesa8 loss-of-function mutants resulted in rescue of the corresponding mutant phenotypes. This work therefore validates the functionality of these utility promoter binary vectors for use in Brachypodium and likely other grass species. The identification, in Bdcesa8-1 T-DNA mutant stems, of an 80% reduction in crystalline cellulose levels confirms that the BdCESA8 gene is a secondary-cell-wall-forming cellulose synthase.

First record of Styracoxylon (Styracaceae) from Southern Hemisphere: Arroyo Feliciano Formation (Upper Pleistocene), Entre Ríos, Argentina

A new species, Styracoxylon thyllosum sp. nov., is described from the Upper Pleistocene Arroyo Feliciano Formation of the Gualeguay Basin in eastern Argentina. It is the first unequivocal record of the Styracoxylonvan der Burgh (1978) in South America and was previously known only from the Pliocene of the Rhine area, Netherlands. This fossil specimen was recovered in the Consorcio Paso Sociedad Locality (Federal, Entre Ríos, Argentina). The new fossil species is characterized by growth ring boundaries distinct, with diffuse-porous wood. Vessels are mostly in radial multiples of 2–6 elements, occasionally solitary and rarely in clusters. Tylosis is abundant. Perforation plates are usually scalariform (5–20 bars) and rarely simple. Intervessel pits are small, bordered, and alternate to opposite. Rays are frequently 2–4 (6) seriate and rarely uniseriate, heterocellular, and of two distinct ray sizes. Fibers are non-septate, with distinctly bordered pits, and rounded to hexagonal in outline.The axial parenchyma is apotracheal diffuse and diffuse-in-aggregates, and in strands of 8–12 cells. Vascular tracheids possibly present. Wood anatomical features suggest a relationship with Styracaceae, and the fossil specimen shows affinity with the extant genus Styrax Linnaeus.

Phylogenetic and Ecological Signals in the Wood of Spathelioideae (Rutaceae)

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.

Wood Anatomy of Chenopodiaceae (Amaranthaceae s.l.)

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.

Wood Anatomy Of Flueggea Anatolica (Phyllanthaceae)

Wood anatomy of Flueggea anatolica Gemici, a relictual endemic from southern Turkey, is described and compared with wood of its presumed relatives in Phyllanthaceae (formerly Euphorbiaceae subfamily Phyllanthoideae). Wood of this critically endangered species may be characterized as semi-ring porous with mostly solitary vessels bearing simple perforations, alternate intervessel pits and helical thickenings; imperforate tracheary elements include helically thickened vascular tracheids and septate libriform fibers; axial parenchyma consists of a few scanty paratracheal cells; rays are heterocellular, 1 to 6 cells wide, with some perforated cells present. Anatomically, Flueggea anatolica possesses a syndrome of features common in Phyllanthaceae known in previous literature as Glochidion-type wood structure; as such, it is a good match for woods from other species of the genus Flueggea.

Wood Anatomy of Endemic RHAMNUS Species In The Mediterranean Region of Turkey

The wood anatomy is described of five Rhamnus species endemic in the Mediterranean region of Turkey, and ecological adaptations are discussed. The wood of all species is drought-adapted with low mesomorphy values (range 11–23), high vessel frequencies (277–457/mm2), spiral thickenings, low vessel diameters (22–35 μm) and short vessel elements (189–240 μm). The vessels are grouped in a dentritic pattern with abundant vasicentric and vascular tracheids.

Two distinct cell sources of H2O2 in the lignifying Zinnia elegans cell culture system

The use of transdifferentiating Zinnia elegans mesophyll cells has proved useful in investigations of the process of xylem differentiation from cambial derivatives. Cultured mesophyll cells can be induced by external stimuli to proceed through temporally controlled developmental programs which conclude in the formation of single-cell-derived dead vascular tracheids and parenchyma-like elements. However, there is a gap in our knowledge concerning the role played by reactive oxygen species (O(2) (-) and H(2)O(2)) in the development of these vascular elements. In this study, we show by the following four independent and highly selective methods that transdifferentiating Z. elegans mesophyll cells are capable of producing reactive oxygen species: the 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) assay, which monitors O(2) (-) production, and the xylenol orange, 2,7-dichlorofluorescein diacetate, and CeCl(3) assays, which monitor H(2)O(2) production and localization. The joint use of these biochemical (XTT and xylenol orange) assays and cytochemical (2,7-dichlorofluorescein diacetate and CeCl(3)) probes revealed that transdifferentiating Z. elegans mesophyll cells do not show an oxidative burst but live in a strongly oxidative state during the entire culture period. In this state, H(2)O(2) is produced by both tracheary and parenchyma-like elements, the nonlignifying parenchyma-like cells acting quantitatively as the main source. The existence of these two sources of H(2)O(2) in this in vitro cell culture system may be especially relevant during the later stages of tracheary cell wall lignification, in which lignifying tracheary elements become hollow. In the case of differentiating tracheary elements, H(2)O(2) was located in the same place and at the same time as the onset of tracheary element lignification, i.e., at the primary cell wall during secondary thickening, supporting the view that the H(2)O(2) produced by this in vitro culture system is destined for use during lignin biosynthesis.

Intervascular pit membranes with a torus in the wood of Ulmus (Ulmaceae) and related genera.

• The distribution of intervascular pit membranes with a torus was investigated in juvenile wood samples of 19 species of Ulmus and seven related genera. • A staining solution of safranin and alcian blue (35:65) was recommended to distinguish torus-bearing pit membranes using light microscopy. • Intervascular pit membranes connecting relatively wide vessel elements resembled those of most angiosperms, as they were of uniform thickness. By contrast, bordered pit pairs with round to oval pit apertures and indistinct pit canals that connected narrow (incomplete) vessel elements or vascular tracheids with distinct helical thickenings were frequently characterized by a torus in ring-porous wood samples of Ulmus and Zelkova. Tori were lacking in diffuse-porous species of Ampelocera, Aphananthe, Gironniera, Holoptelea, Phyllostylon, Trema and Ulmus. • Our observations suggest that tori are more common in cold temperate climates than in warm (sub)tropical environments. This may indicate that narrow tracheary elements with torus-bearing pit membranes provide an auxiliary conducting system which is of low conductivity, but offers greater resistance to freezing-induced cavitation.

Biomechanics and anatomy of cladode junctions for two Opuntia (Cactaceae) species and their hybrid

Hybridization between the introduced arborescent Opuntia ficus-indica and the native shrubby O. littoralis has led to populations, referred to as O. "occidentalis," which form thickets that can dominate hillsides of chaparral and that can survive fires. Because the thickets apparently develop via vegetative reproduction, O. "occidentalis" was hypothesized to have a greater ability than its parent species to reproduce vegetatively due to weaker cladode junctions. Of the three taxa, the junctions for O. "occidentalis" had the least amount of wood, despite having cladode masses and junction cross-sectional areas similar to those of O. littoralis. The cladodes of O. "occidentalis" resisted deflection about their junctions the least and their junctions required the least amount of applied mass and the smallest bending moment to fail mechanically. The junction wood for all three taxa consisted mostly of parenchyma, with lesser amounts of cells with thickened secondary cell walls, indicating that some junction strength depended on hydrostatic pressure, especially for terminal junctions. Libriform fibers, which contribute to support and resist bending moments, were about 80% less frequent in the sub-subterminal junctions of O. "occidentalis" than in O. ficus-indica and O. littoralis. Vascular tracheids, which probably reduced shear among cells in the wood, were 90% less frequent in the terminal and sub-subterminal junction wood of O. "occidentalis" compared to O. littoralis. Thus wood characteristics can account for the weaker junctions of O. "occidentalis" compared to those of O. ficus-indica and O. littoralis, which apparently increases the ability of the hybrid to reproduce vegetatively.

Wood anatomy of Elaeagnaceae, with comments on vestured pits, helical thickenings, and systematic relationships

The secondary xylem of Elaeagnus, Hippophae, and Shepherdia is described and illustrated in detail. Shrubs and small trees of Elaeagnaceae have ring-porous or semi-ring-porous wood with simple perforation plates, vascular tracheids, fiber-tracheids, diffuse or rarely paratracheal axial parenchyma, and uni- or biseriate rays in Hippophae and Shepherdia, but wider rays in Elaeagnus. Walls of vessel elements, especially narrow ones, tracheids, or fiber-tracheids sometimes show helical thickenings; in a few instances these intergrade with small bud-like protrusions associated with pits. Scanning electron microscopy illustrates that small to vestigial vestures are present in all species studied, although nonvestured pits are also common. The analogous nature of vestures and helical thickenings is considered. Comparative wood anatomy suggests a rather isolated position of the family Elaeagnaceae; affinities with Rhamnaceae, Proteaceae, and Thymelaeaceae are discussed.

Wood anatomy of six species of Lycium, with comments on fibriform vessel elements

The study of wood anatomy of 6 species of Lycium L. was made. These species share an homogeneous structure. The essential wood characteristics are: dendritic distribution, presence of spiral thickness in the secondary wall of vascular elements and tracheids, apotracheal and paratracheal axial parenchyma, radial heterogeneous, and libriform fibres. The presence of fibriform vessel elements is described in 6 six species of Lycium for the first time.

Wood Anatomy of Portulacaceae and Hectorellaceae: Ecological, Habital, and Systematic Implications

Qualitative and quantitative wood data are given for 13 species of 10 genera of Portulacaceae (secondary xylem from additional species of Anacampseros and Lewisia were studied but not quantitatively analyzed). Most Portulacaceae show modifications that can be related to the succulent habit, including wide, tall rays mostly composed of thin-walled cells; total or partial substitution of axial parenchyma for libriform fibers ; and modified patterns of pitting on lateral walls of vessels. Pseudoscalariform pitting is more common in Portulacaceae than in other dicotyledon families. In vessels of Anacampseros wood, wide helical bands of secondary wall materi al are present. Similar helices (but without the unusual width) occur in the wood of Lewisia and Heclorella. Woods of Portulacaceae as a whole are markedly xeromorphic with respect to vessel e lement dimensions, vessel density, and vessel grouping; wood of Lewisia and Hectorella is especi ally xeromorphic. Xeromorphism is not so pronounced in succulent dicotyledons at large. Woods of species of Portulacaceae with less marked adaptation to succulence show close resemblance to woods of Didiereaceae and woodier Cactaceae, suggesting the validity of the suborder Portulacineae, which includes these three families plus Hectorellaceae and Basellaceae. The wood of Heclorella is very similar to that of Lewisia rediviva and contains no features not also observed in Portulacaceae. Tracheidlike idioblasts in rays of Anacampseros are likely not homologous with wide-band vascular (or vasicentric) tracheids in fascicular secondary xylem of globular cacti. Dark-colored mucilage idioblasts in Portulacaceae are likely to be a homoplasy; they occur in a scattering of Caryophyllales.

Wood Anatomy of Buddlejaceae

Quantitative and qualitative data are presented for 23 species of Buddleja and one species each of Emorya, Nuxia, and Peltanthera. Although crystal distribution is likely a systematic feature of some species of Buddleja, other wood features relate closely to ecology. Features correlated with xeromorphy in Buddleja include strongly marked growth rings (terminating with vascular tracheids), narrower mean vessel diameter, shorter vessel elements, greater vessel density, and helical thickenings in vessels. Old World species of Buddleja cannot be differentiated from New World species on the basis of wood features. Emorya wood is like that of xeromorphic species of Buddleja. Lateral wall vessel pits of Nuxia are small (2.5 ILm) compared to those of Buddleja (mostly 5-7 ILm) . Peltanthera wood features can also be found in Buddleja or Nuxia; Dickison's transfer of Sanango from Buddlejaceae to Gesneriaceae is justified. All wood features of Buddlejaceae can be found in families of subclass Asteridae such as Acanthaceae, Asteraceae, Lamiaceae, Myoporaceae, Scrophulariaceae, and Verbenaceae. Wood anatomy of Buddlejaceae relates to species ecology and size of wood sample, and is not useful in demonstrating that Buddlejaceae are closer to any particular one of these families; such evidence must be sought in molecular data and elsewhere.

Comparative wood anatomy ofCoriaria

Wood anatomy ofCoriaria was surveyed to clarify generic features on the basis of 14 species collected from various regions of the World to cover the whole range of geographic distribution and habitual variation. Wood anatomy ofcoriaria is considerably uniform, and the species share a combination of the following features: 1) pores are thin-walled, polygonal in outline and mostly in multiples; 2) vessel elements and libriform fibers are very short; 3) perforation plates are exclusively simple; 4) intervessel pits are alternate; 5) vascular tracheids are present; 6) wood parenchyma is vasicentric and sometimes confluent; 7) rays are heterogeneous and large. Its species differ in several characters, such as distinctness of growth rings, pore size, pore patterns, type and abundance of wood parenchyma, and distinctness of storied structure. Comparisons among species indicate that the species of the Northern Hemisphere show a tendency toward having semi-ring porosity, while those of the Southern and Western Hemisphere have diffuse porosity. The other infrageneric variations appear to be related to different habits of the species rather than to geographic distribution. Small trees mostly have confluent and vasicentric parenchyma composed of fusiform cells and distinctly storied tissues, while shrubs and herbs have less abundant parenchyma which is vasicentric and comprises strands of two to four cells and indistinctly storied tissues.

Wood Anatomy of Lamiaceae. A Survey, with Comments on Vascular and Vasicentric Tracheids

Wood Anatomy of Lamiaceae. A Survey, with Comments on Vascular and Vasicentric Tracheids

Diversity and significance of late cretaceous permineralized plant remains from Hokkaido, Japan

Middle to Late Cretaceous permineralized plants hitherto described from Hokkaido, Japan are summarized. The fossil flora comprises fungi, ferns, gymnosperms and angiosperms. Many modern fern families have been recognized including Anemiaceae, Cyatheaceae, Dennstaedtiaceae, Gleicheniaceae Loxsomaceae, Lygodiaceae and Matoniaceae. Gymnosperms are most abundant in the flora. Some recently-found materials are tentatively introduced with brief comments emphasizing their morphological and taxonomical significance. A bisporangiate flower ofCycadeoidella japonica Ogura shows fine internal anatomy and provides evidence that the cycadeoidalean ovule was a cupulate, unitegmic structure. Vascular tracheids in the synangial wall support the evolution of cycadeoidalean synangia from Paleozoic seed-fern synangia. A new gymnosperm female fructification has a thick envelope comparable to an angiosperm carpel around a large seed. The angiosperms contain various morphologies that require further extensive study.