Metabolite profiling reveals complex relationship between developing xylem metabolism and intra-ring checking in Pinus radiata

Globally, there has been an increasing amount of wood harvested from younger, fast-growing trees derived from plantation forests. As a consequence, producers and industrial consumers of wood products are becoming increasingly concerned with not only growth rates, but specific wood attributes that affect processing efficiencies and final product quality. Intra-ring checking is a problem that down-grades an unacceptably high proportion of radiata pine clearwood. Methods of identifying trees prone to this undesirable behaviour have been relatively destructive and time consuming, and from a breeding perspective, to date, there is no reliable method of predicting which selected progeny will later show a propensity to check. Using 120, 7-year-old Pinus radiata clones sampled from a common site, displaying difference in the propensity to form intra-ring checks, a GC/MS-based global metabolic profiling technique was employed to demonstrate that metabolomics can be used to accurately identify the checking phenotype. Metabolic profiling coupled with statistical tests was then used to develop models with greater than 90% efficiency to predict the intra-ring checking phenotype. Moreover, an inspection of unique metabolites contributing to the models indicated that coniferin, which is often found as a storage compound in rays, is a strong indicator of intra-ring checking, and indeed those genotypes that displayed the propensity to check inherently had a greater number of ray cells per unit area.

Structure of the secondary xylem and development of a cambial variant in Serjania mexicana (Sapindaceae)

The lianas in the family Sapindaceae are known for their unique secondary growth which differs from climbing species in other plant families in terms of their cambial variants. The present study deals with the stem anatomy of self-supporting and lianescent habit, development of phloem wedges, the ontogeny of cambial variants and structure of the secondary xylem in the stems of Serjania mexicana (L.) Willd. Thick stems (15–20 mm) were characterized by the presence of distinct phloem wedges and tangentially wide neo-formed cambial cylinders. As the stem diameter increases, there is a proportional increase in the number of phloem wedges and neo-formed vascular cylinders. The parenchymatous (pericyclic) cells external to phloem wedges that are located on the inner margin of the pericyclic fibres undergo dedifferentiation, become meristematic and form small segments of cambial cylinders. These cambia extend tangentially into wide and large segments of neoformations. Structurally, the secondary xylem and phloem of the neo-formed vascular cylinders remain similar to the derivatives produced by the regular vascular cambium. The secondary xylem is composed of vessels (wide and narrow), fibres, axial and ray parenchyma cells. The occurrence of perforated ray cells is a common feature in both regular and variant xylem.

COMPARATIVE PROTEOMIC ANALYSIS OF THE THICK-WALLED RAY FORMATION PROCESS OF HALOXYLON AMMODENDRON IN THE GURBANTUNGGUT DESERT, CHINA

Thick-walled ray cells of Haloxylon ammodendronwere first reported by Zhou and Gong in 2017, but their formation mechanism remains unknown. In this study, we performeda proteomic analysis of ray cell wall formation in the xylem. H. ammodendronin Shihezi exhibits a thicker ray cell wall than that in Jinghe. During the process of cell wall biosynthesisin the xylem of H. ammodendron, the nonspecific lipid-transfer protein and beta expansin EXPB2.1 (Mirabilis jalapa) first loosen the cell wall, and this step is followed by extension and expansion. Subsequently, xyloglucan endotransglycosylase/hydrolase 1 cleaves and linksthe xyloglucan chains. Photosystem I P700 apoprotein A1, reversibly glycosylated polypeptide 1 and GDP-mannose-3′,5′-epimerase are involved in the cellulose, hemicellulose and pectin biosynthesis processes in the cell wall by providing components or energy. Finally, the proteins involved in phenylpropanoid biosynthesis promote lignification of the ray cell wall and complete the biosynthetic process of the cell wall.

Wood micro-morphological characteristics of the Tribe Dalbergieae in Nigeria

The present study examined the wood micro-characters of 18 species of the tribe Dalbergieae across 4 genera in Nigeria, following previously described methods by other authors. The species are distributed across all geo-ecological zones of the country but more abundant in the southern area which is characterized by higher precipitation. Findings clearly showed that members of the tribe Dalbergieae have more generic/tribal characteristics than delimiting characters. The species have certain unifying characters such as diffuse pore porosity, simple perforation plates, oblique to orthogonal vessel transverse wall inclination, prismatic/styloid crystals, and non-septate fibres. Vessels were longest and widest in D. saxatilis, about 197.89x104.23µm. On the contrary, the shortest was observed in D. hostilis - 67.62 µm while the narrowest was in D. oligophylla (28.4 µm). While fibre length was highest in P. mildbraedii (331.22 µm±7.5) and smallest in D. saxatilis (0.69 µm±0.0), the ray cells were longest in D. saxatilis (185µm) and shortest in P. santalinoides (41.82µm) respectively. We confirm here that anatomical studies should not be neglected in plant systematics, even though molecular approaches have been the focus in recent times.

Systematic wood anatomical study in some species of Sapindaceae Juss. in South-Western Nigeria

Comparative wood anatomical studies was carried out on ten species in the family Sapindaceae. The species were relatively uniform in the features of their vessels, in which diffuse porous was observed with solitary vessels to pore multiples in transverse section and ray cells were predominantly heterogeneous in radial section. Fibres were long and extensive. The longest fibre was observed in Blighia sapida (1025±28.5 µm), while the shortest fibre was observed in Cardiospermum halicacabum (139±6.5 µm). The longest vessel was observed in Deinbolia pinnata (509±34.9 µm) and the shortest vessel was observed in Cardiospermum halicacabum (85.36±4.9 µm). The implication of these features in the taxonomy of the family was discussed. The Dendrogram based on the quantitative wood characters confirmed Allophylus africanus and Allophylus spicatus belong to the same genus as classified, likewise Blighia unijugata, Blighia sapida but Cardiospermum halicacabum is closely related to Paullinia pinnata while others exhibited distinct generic characters.

Influence of morphology on the effective hygro-elastic properties of softwood (spruce) and hardwood (balsa)

Wood materials are characterized by complex, hierarchical material structures spanning across various length scales. The present work aims at establishing a relation between the hygro-elastic properties at the mesoscopic cellular level and the effective material response at the macroscopic level, both for softwood (spruce) and hardwood (balsa). The particular aim is to explore the influence on the effective hygro-elastic properties under variations in the meso-scale morphology. The multi-scale framework applied for this purpose uses the method of asymptotic homogenization, which allows to accurately and efficiently obtain the effective response of heterogeneous materials characterized by complex meso-structural geometries. The meso-structural model considered for softwood is based on a periodic, two-dimensional statistically representative volume element that is generated by a spatial repetition of tracheid cells. The tracheid cells are modeled as hexagonal elements characterized by a certain geometrical irregularity. The hardwood meso-structure consists of a region composed of hexagonal cellular fibers with large vessels embedded, which is connected to a ray region that is constructed of ray cells. The hardwood fibers are modeled as hexagonal cellular elements, similar to softwood tracheids. The rays are represented by quadrilateral cells oriented along the radial direction, whereby different arrangements are considered, i.e., the ray cells are either regularly stacked or organized as a staggered configuration. The interface between the fiber and ray regions may also be characterized by a regular or a staggered arrangement. The meso-structural models for softwood and hardwood are discretized by means of plane-strain, finite element models, which describe the hygro-elastic response of the wood material in the radial–tangential plane. For softwood, the sensitivity of the effective elastic and hygro-expansive properties is explored as a function of the geometrical irregularity of the tracheids. For hardwood, the effective properties are studied under a variation of the ray cell arrangement, the type of interface between ray and fiber regions, and the vessel volume fraction. The modeling results agree well with results obtained from other numerical homogenization studies and show to be in reasonable agreement with experimental data taken from the literature.

Comparison of anatomical features in the three Syzygium species

This study was conducted to provide foundational anatomical information of three infrequently used wood species growing in tropical areas. Three species of the genus Syzygium, namely the clove tree, kupa, and spicate eugenia, were selected. The representative anatomical features of these species were classified using the International Association of Wood Anatomists (IAWA) anatomical feature list. The representative anatomical features of the clove tree included the distribution of small vessels with tangential diameters of approximately 60 µm in cross-surface, a dense spacing of vessels, the axial parenchyma in narrow bands or lines up to three cells wide, and the body ray cells procumbent with over four rows of upright and/or square marginal cells. The kupa showed axial parenchyma confluent and the body ray cells were procumbent with over four rows of upright and/or square marginal cells. In the spicate eugenia, the axial parenchyma was diffused in aggregate with exclusively uniseriate rays and the body ray cells were procumbent with one row of upright and/or square marginal cells. These three species were easily identified by optical microscopy via the anatomical features of the woods.

Calcium Sulfate Hemihydrate (Bassanite) Crystals in the Wood of the Tamarix Tree

The most abundant mineral produced in the wood and leaves of trees is calcium oxalate monohydrate (whewellite), and after burning the wood the ash obtained is calcite. In the case of the Tamarix sp. tree, the freshly prepared ash is calcium sulfate (anhydrite). The aim of this study is to determine the calcium sulfate mineral phase in the fresh wood of Tamarix aphylla prior to burning. SEM images of the crystals show that they express smooth faces, are about 5–15 microns in their longest dimensions and are located in the ray cells. Fourier transform infrared spectroscopy (FTIR) and Raman microspectroscopy of the crystals in the wood and after extraction, both showed that the crystals are composed of calcium sulfate hemihydrate (bassanite). As elemental analyses of the crystals showed that in addition to calcium and sulfur, around 20 atom percent of the cations are sodium and potassium, we also obtained an X-ray powder diffraction pattern. This pattern excluded the possibility that the crystals are composed of another related mineral, and confirmed that, indeed, the crystals in the T. aphylla wood are composed of calcium sulfate hemihydrate (bassanite).

Wood identification of an ancient Greek coffin from the Bosporan Kingdom

Wood identification of 13 samples is made for the first time for the well-preserved coffin from the Bosporan Kingdom exhibited in the State Hermitage Museum. Due to the decay state, observation was carried out with Scanning Electron Microscopy. Additional information was obtained from macerated material. The samples studied show a complex of characteristics common to the Cupressaceae family: axial tracheids without helical thickenings, presence of axial parenchyma, homogeneous rays, cupressoid cross-field pits, and absence of resin canals. The presence of dark-stained content in the ray cells and the structure of its end walls, as well as the size of the rays, allow the determination of the wood samples as Cupressus sp. and Juniperus sp. The supporting parts of the coffin construction are made from cypress, while the decorative details and an inner bed are from juniper. These results support the dating of the coffin and the known information about different usage of timbers in the production of coffins in the Bosporan Kingdom.

Oak wood drying: precipitation of crystalline ellagic acid leads to discoloration

Oak heartwood usually darkens during and after drying. This darkening can be heterogeneous, leaving non-colored areas in the wood board. These light discolorations have been linked to heterogeneous distribution of tannins, but compelling evidence on the microscale is lacking. In this study Raman and fluorescence microscopy revealed precipitations of crystalline ellagic acid, especially in the ray cells but also in lumina, cell corners and cell walls in the non-colored areas (NCA), which also had higher density. In these denser areas free water is longer present during drying and leads to accumulation of hydrolyzed tannins. When eventually falling dry, these tannins precipitate irreversible as non-colored ellagic acid and are not available for chemical reactions leading to darkening of the wood. Therefore, pronounced density fluctuations in wood boards require adjusting the drying and processing parameters so that water domains and ellagic acid precipitations are avoided during drying.