Timber Properties and Cellulose Crystallites Size in Pine Wood Cut in Different Sawing Patterns after Pretreatment with CH3COOH and H2O2 and Densification

One process to improve wood quality is densification or wood surface compression. Our study analyzed the changes in some basic properties of pine wood, including its anatomical structure, density, modulus of elasticity (MOE), and dimensions of cellulose crystallites, after densification following soaking pretreatment in CH3COOH and H2O2 at a concentration of 20%. Samples were sawn in radial and tangential directions for analysis of the wood. The results showed a change in the shape of tracheid cells from hexagonal to oval, as well as damage to the ray cell constituents on the tangential surface. The thickness decrease of the samples was in accordance with the target, which meant that spring-back was short. In general, the tangential boards had a higher density than the radial boards, with a lower MOE and crystallite dimensions. Our findings showed that the densified tangential board was stronger than the radial board.

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.

Cedroxylon shakhtnaense (Blokhina 2010) Dolezych, Mantzouka et L.Kunzmann comb. nov.; A fossil Abies wood from the late early Miocene Mastixioideae flora of Wiesa (east Germany)

We describe the first evidence of fossil Abies wood from the late early Miocene fossil plant assemblage of Wiesa in east Germany. The comparatively well-preserved piece of xylitic wood was recovered in the kaolin quarry at Hasenberg hill in Wiesa. The Wiesa assemblage is characterized as being allochthonous and partly parautochthonous mass deposits of diaspores, leaves, and wood. The latter component is rather incompletely studied so far. The described fossil is characterized by high rays, mostly uniseriate bordered pits, generally thick and pitted horizontal and tangential ray cell walls, but also partly smooth horizontal ray cell walls, absence of ray tracheids, the occurrence of traumatic resin canals, and rare occurrence of axial parenchyma of two types. This type of fossil wood has been described as Abietoxylon shakhtnaense Blokhina from the Oligo-Miocene of Sakhalin, Russia. Due to nomenclatural issues of Abietoxylon a recombination to Cedroxylon Kraus emend. Gothan is proposed following common practice for affiliation of abietoid fossil wood of Cenozoic age. Cedroxylon shakhtnaense comb. nov. shares anatomical characteristics with the wood of extant Abies Mill., in particular with sections Abies and Grandis, and is most closely related to section Grandis. The properly preserved fossil wood from Wiesa provides the opportunity of applying qualitative and quantitative analyses for testing and discussing its placement in relationship to intra-tree variability and ontogenetic aspects. The first evidence of fossil wood of Abies from Wiesa confirms again the presence of the genus in mid-latitude subtropical zonal vegetation during the beginning of the Miocene Climatic Optimum.

The Spatio-Temporal Distribution of Cell Wall-Associated Glycoproteins During Wood Formation in Populus

Plant cell wall associated hydroxyproline-rich glycoproteins (HRGPs) are involved in several aspects of plant growth and development, including wood formation in trees. HRGPs such as arabinogalactan-proteins (AGPs), extensins (EXTs), and proline rich proteins (PRPs) are important for the development and architecture of plant cell walls. Analysis of publicly available gene expression data revealed that many HRGP encoding genes show tight spatio-temporal expression patterns in the developing wood of Populus that are indicative of specific functions during wood formation. Similar results were obtained for the expression of glycosyl transferases putatively involved in HRGP glycosylation. In situ immunolabelling of transverse wood sections using AGP and EXT antibodies revealed the cell type specificity of different epitopes. In mature wood AGP epitopes were located in xylem ray cell walls, whereas EXT epitopes were specifically observed between neighboring xylem vessels, and on the ray cell side of the vessel walls, likely in association with pits. Molecular mass and glycan analysis of AGPs and EXTs in phloem/cambium, developing xylem, and mature xylem revealed clear differences in glycan structures and size between the tissues. Separation of AGPs by agarose gel electrophoresis and staining with β-D-glucosyl Yariv confirmed the presence of different AGP populations in phloem/cambium and xylem. These results reveal the diverse changes in HRGP-related processes that occur during wood formation at the gene expression and HRGP glycan biosynthesis levels, and relate HRGPs and glycosylation processes to the developmental processes of wood formation.

Comparative proteomic analysis of thick-walled ray formation of Haloxylon ammodendron in the Gurbantunggut Desert, China

Background The thick-walled ray cells have been reported in Haloxylon ammodendron for the first time. This study measured the wall thickness of ray cells and performed a proteomic analysis of ray cell wall formation in the xylem of H. ammodendron using isobaric tags for relative and absolute quantitation. Results The wall thickness of ray cells in Jinghe (2.85 ± 0.42 µm) was significantly lower than that in Shihezi (3.08 ± 0.44 µm) (P < 0.01). In Shihezi, which has a thicker wall of ray cells than that in Jinghe, 795 differentially expressed proteins were upregulated. Phenylpropanoid biosynthesis, photosynthesis, glycolysis/gluconeogenesis, carbon metabolism, starch and sucrose metabolism, metabolic pathways, etc. promote ray cell wall biosynthesis of the xylem of H. ammodendron by providing substrates or energy. During the process of cell wall biosynthesis in the xylem of H. ammodendron, the nonspecific lipid-transfer protein and beta expansin EXPB2.1 (Mirabilis jalapa] first loosens the cell wall, followed by extension and expansion, and the xyloglucan endotransglycosylase/hydrolase 1 cleaves and links the xyloglucan chains. Then, photosystem I P700 apoprotein A1, reversibly glycosylated polypeptide 1 and GDP-mannose-3′, 5′-epimerase, etc., are involved in cellulose, hemicellulose and pectin biosynthesis of the cell wall by providing components or energy. Finally, the proteins in phenylpropanoid biosynthesis promote the lignification of the ray cell wall and complete the biosynthetic process of the cell wall. Conclusions Phenylpropanoid biosynthesis, photosynthesis, glycolysis/gluconeogenesis, carbon metabolism, starch and sucrose metabolism, metabolic pathways, etc. promote ray cell wall biosynthesis of the xylem of H. ammodendron by providing substrates or energy. The results are important for improving the wood mechanical properties of timber plantations.

Position of rays and lateral deviation of vessel elements in the stem wood of some dicotyledonous species with storeyed, double-storeyed, and nonstoreyed cambia

It is believed that differentiating vessel elements increase their diameter by growing intrusively in the circumferential direction and symplastically in the radial direction in relation to the stem axis. On the basis of a detailed analysis of the cell arrangement observed in a series of semithin anatomical sections of cambial zone and the developing and mature secondary xylem of Terminalia ivorensis , Wisteria floribunda , and Millettia laurentii , we revealed a novel correlation of growing vessel elements with surrounding tissues. Rays seem to prevent the growing vessel elements from protruding laterally between the cells of adjacent rays. The growing vessel elements break the continuity of several neighbouring radial files of fusiform cell derivatives but not of ray cell derivatives. If a contiguous ray becomes an obstacle for the growth of vessel elements on any one side, the growing elements often start to grow in the opposite direction, consequently causing a deviation in the alignment of the vessel elements concerned. This mechanism explains why vessel elements may deviate from the array of their precursors, the fusiform cambial initials. Our models on the intrusive symplastic growth of vessel element mother cells have revealed that intrusive growth does not occur between radial walls of neighbouring cells.

Vertical migration of rays leads to the development of a double-storied phenotype in the cambium of Aesculus turbinata

In the vascular cambium of Aesculus turbinata (Blume) the double-storied structure develops slowly. Initially, the arrangement of primary rays is nonstoried. New secondary rays are initiated during cambial expansion. Rays grow by addition of new initials at both ray margins and then split by the intrusive elongation of adjacent fusiform cells. The repetitive splits give rise to groups of several rays of common descent. Initially, the secondary rays are also nonstoried. Later, they become organized into horizontal tiers. This results from the vertical migration of ray initials in the vascular cambium. Controlled polar additions and eliminations of ray-cell initials at the opposite margins of the ray continue until it reaches the appropriate position within the storey of fusiform initials. We postulate that there are at least two mechanisms for the formation and maintenance of ray tiers in cambium. They are unrelated to cell inclination changes, which as described earlier, are known to sometimes induce a double-storied phenotype. The first of these mechanisms, involves initiation of secondary rays exactly within the storeys of fusiform initials, as in Hippophaë rhamnoides L. The second mechanism, present in A. turbinata, is based on the dynamic, controlled migration of rays.