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The visualization and evaluation of fruit vascular bundles in grape are indispensable for understanding the development and growth of the fruit. The vascular bundles in grape are as thin as human hair, and strongly adhere to flesh cells, making it difficult to isolate individual intact vessel elements. Currently there is little information about methods to characterize grape vascular tissue. In this study, we describe an easy and effective technique to visualize the xylem cell structure of the ‘Red Globe’ grape (Vitis L.). The intact vascular bundles of the grape were isolated through enzymatic degradation of flesh cells by hydrolases which were effective in removing flesh cells from vascular bundles. This enabled the illustration of the fine surface structure of vessel elements and their arrangement in the vascular bundles of the grape. This modified method to separate the vascular bundles into individual vessel elements was more effective than former methods of manually shaking to isolate individual vessels. Clear images of xylem vessel arrangement and structural characteristics of individual vessel element were acquired by light microscopy (BX51, Olympus, Tokyo, Japan), transmission electron microscopy (Tecnai 12, Philips, Netherlands) and scanning electron microscopy (GeminiSEM 300, Carl Zeiss, Germany). In addition, the 3D structure of vessel elements was observed using confocal laser scanning microscopy (Zeiss: model: LSM-880, Oberkochen, Germany). The imaging techniques for visualizing and analyzing the structure of xylem vessels in grape described in this study are an improvement of past methods. An effective method to isolate grape vascular bundles from flesh cells was also developed, which enables the imaging of the fine surface structure of vessel elements and their arrangement in grape vascular bundles. By adjusting the process of maceration of vascular bundles, an easy and effective method was developed to gently disrupt the plant tissue and isolate individual vessel elements. These improved techniques are suitable to observe the intact morphology of vascular bundles in the grape, improve experimental efficiency and accelerate new discoveries on the anatomical structure of the grape.

Creep behavior of wood plays a fundamental role in precision processing of wood. In this work, experimental creep tests have been conducted to determine the influence of earlywood vessel location and moisture content on creep behavior of Quercus alba (white oak). Time-moisture superposition principle was applied to predict long-term creep behavior of white oak. Results revealed that both of instantaneous and 45-min strain of specimens increased with the increasing of moisture content and decreased with increasing distance between earlywood vessel belt and load-bearing surface significantly. Additionally, the time-moisture superposition principle was found to have feasibility to predict creep behavior of white oak with various earlywood vessel locations and moisture content ranges (6 % - 18 %). We believe that the proposed investigation was beneficial for the processing precision and civil engineering applications of wood.

Abstract Background Xylem, the most abundant tissue on Earth, is responsible for lateral growth in plants. Typical xylem has a radial system composed of ray parenchyma cells and an axial system of fusiform cells. In most angiosperms, fusiform cells comprise vessel elements for water transportation and libriform fibers for mechanical support, while both functions are performed by tracheids in other vascular plants such as gymnosperms. Little is known about the developmental programs and evolutionary relationships of these xylem cell types. Results Through both single-cell and laser capture microdissection transcriptomic profiling, we determine the developmental lineages of ray and fusiform cells in stem-differentiating xylem across four divergent woody angiosperms. Based on cross-species analyses of single-cell clusters and overlapping trajectories, we reveal highly conserved ray, yet variable fusiform, lineages across angiosperms. Core eudicots Populus trichocarpa and Eucalyptus grandis share nearly identical fusiform lineages, whereas the more basal angiosperm Liriodendron chinense has a fusiform lineage distinct from that in core eudicots. The tracheids in the basal eudicot Trochodendron aralioides, an evolutionarily reversed trait, exhibit strong transcriptomic similarity to vessel elements rather than libriform fibers. Conclusions This evo-devo framework provides a comprehensive understanding of the formation of xylem cell lineages across multiple plant species spanning over a hundred million years of evolutionary history.

Despite extensive knowledge about vessel element growth and the determination of the axial course of vessels, these processes are still not fully understood. They are usually explained as resulting primarily from hormonal regulation in stems. This review focuses on an increasingly discussed aspect – mechanical conditions in the vascular cambium. Mechanical conditions in cambial tissue are important for the growth of vessel elements, as well as other cambial derivatives. In relation to the type of stress acting on cambial cells (compressive versus tensile stress) we: (i) discuss the shape of the enlarging vessel elements observed in anatomical sections; (ii) present hypotheses regarding the location of intrusive growth of vessel elements and cambial initials; (iii) explain the relationship between the growth of vessel elements and fibres; and (iv) consider the effect of mechanical stress in determining the course of a vessel. We also highlight the relationship between mechanical stress and transport of the most extensively studied plant hormone – auxin. We conclude that the integration of a biomechanical factor with the commonly acknowledged hormonal regulation could significantly enhance the analysis of the formation of vessel elements as well as entire vessels, which transport water and minerals in numerous plant species. [ABSTRACT FROM AUTHOR]

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Key message: In some circumstances vessel elements, both broad and narrow, enlarge only symplastically in tangential direction. Rays play a special role in regulating intrusive enlargement of vessel elements. The aim of this study was to analyse relations occurring between vessel elements and surrounding cells, i.e. susceptibility to separation of walls of cells occurring in the vicinity of vessel elements, with regard to their type—cells of the axial/radial system. On the basis of separation/lack of separation of cell walls, and thus change in cell contacts/lack of change in cell contacts, we have estimated the contribution of particular types of growth—intrusive and symplastic—in the formation of vessel elements in: Acer pseudoplatanus, Betula pendula, Catalpa bignonioides, Quercus robur and Robinia pseudoacacia. Striking differences in susceptibility to separation of periclinal walls of axial and ray system cells were noticed. Periclinal walls of axial system cells were easily separated, even in cells which were not directly adjacent to vessel elements. Continuity of ray cells was maintained even in cases when the vessel element enlarged directly between two rays. It seems that the direct vicinity of ray increases the contribution, as well as the range of symplastic growth in a tangential direction during vessel element formation. Growth of a vessel element in a tangential direction has been described as intrusive so far. A vessel element seems to enlarge only symplastically, when derived from a mother cell located directly between two rays. Observed differences in susceptibility to separation of cell walls indicate the important role of rays in regulating intrusive expansion of vessel elements. [ABSTRACT FROM AUTHOR]

The potential of some phytodyes were examined to obtain cheap, non- toxic and ecofriendly stains for use in wood anatomy. Phytodyes from Enantia cholorantha, Harungana madagascariensis, Hisbiscus sabdariffa, Sarcocephalus latifolius, Sphenocentrum jollyanum, and Sorghum bicolor were used to stain wood sections and macerates. All the extracts had good affinity for wood fibre and other lignified tissues except Hibiscus sabdariffa. The results of the absorption spectrum of these dyes revealed a range of wavelength of absorption between 300.00 and 900.00 nm. These wavelengths fall within the visible region of the electromagnetic spectrum confirming the presence of colour imparting chromophores in the dyes. Each of the phytodye has minimum of two peaks, indicating that each dye had a minimum of two colour imparting chromophores. All the dyes were acidic with pH range of 2.80 to 5.90. The histochemical reactions of all the phytodyes were similar in that they all imparted their colours indiscriminately on all cells but fibre and lignified tissues took up the dyes more deeply. They were specific when used with Alican blue which have affinity for thin walled cells. Therefore, this study revealed that these dyes could be used solitarily or in combination with artificial dyes for wood histological staining.