3D Visualization of Bamboo Node’s Vascular Bundle

The vascular bundle is an important structural unit that determines the growth and properties of bamboo. A high-resolution X-ray microtomography (μCT) was used to observe and reconstruct a three-dimensional (3D) morphometry model of the vascular bundle of the Qiongzhuea tumidinoda node due to its advantages of quick, nondestructive, and accurate testing of plant internal structure. The results showed that the morphology of vascular bundles varied significantly in the axial direction. In the cross-section, the number of axial vascular bundles reached a maximum at the lower end of the sheath scar, and the minimum of it was at the middle of the diaphragm. The frequency of axial vascular bundles decreased from the lower end of the node to the nodal ridge, and subsequently increased until the upper end of the bamboo node. The proportion of parenchyma, fibers, and conducting tissue was 65.7%, 30.5%, and 3.8%, respectively. The conducting tissues were intertwined to form a complex 3D network structure, with a connectivity of 94.77%. The conducting tissue with the largest volume accounted for 60.26% of the total volume of the conducting tissue. The 3D-distribution pattern of the conducting tissue of the node and that of the fibers were similar, but their thickness changed in the opposite pattern. This study revealed the 3D morphometry of the conducting tissue and fibers of the bamboo node, the reconstruction of the skeleton made the morphology more intuitive. Quantitative indicators such as the 3D volume, proportion, and connectivity of each type of tissue was obtained, the bamboo node was enlarged mainly caused by the particularly developed fibers. This work laid the foundation for a better understanding of the mechanical properties and water transportation of bamboo and revealed the mystery of bamboo node shedding of Q. tumidinoda.

The features of xylem tracheary elements in some herbaceous members of the family Convolvulaceae Horan.

Numerous narrow xylem tracheary elements (tracheids and vessels) are present in liana stems, along with a few wide vessels that perform the main water-conducting function. This trait, known as “vessel dimorphism”, has been identified in studies on water-conducting tissue in autotrophic plants, including a large number of perennial climbing plants and a number of annual vines. Information is lacking on the presence of vessel dimorphism in parasitic plants of the lianescent habit. In this study, we performed a structural analysis of stems in the autotrophic herbaceous vines of Convolvulus arvensis L. and Calystegia sepium (L.) R. Br., as well as in the parasitic vines of Cuscuta monogyna Vahl, Cuscuta planiflora Ten., Cuscuta approximata Bab., and Cuscuta campestris Yunck., of the family of Convolvulaceae Horan. The xylem of C. arvensis and C. sepium contains a few wide conductive elements and many narrow ones. This feature is typical of autotrophic climbing plants. Only narrow tracheary elements are present in the xylem of the parasitic vines of the genus of Cuscuta L. (dodders). The total number of the tracheary elements is an order of magnitude less in the dodders than it is in the autotrophic vines. It is possible that the autotrophic ancestor of dodders lost the characteristic feature of the xylem of climbing plants, known as vessel dimorphism, during its transition to the parasitic lifestyle.

Understanding the Root Xylem Plasticity for Designing Resilient Crops

Xylem is a main road in plant long-distance communication. Through xylem plants transport water, minerals and myriad of signaling molecules. With the onset during early embryogenesis, the development of xylem tissues relays on hormone gradients, activity of unique transcription factors, distribution of mobile miRNAs and receptor-ligand pathways. These regulatory mechanisms are often interconnected and all together contribute to the plasticity of water conducting tissue. Remarkably, root xylem carries water to all above-ground organs and therefore influences all aspects of plant growth. Because of the global warming and increasing water deficit, we need to come up with solutions for the crops of the future. It is clear that structure of water conducting elements directly impacts water transport within the plant. Among plant pathogens- vascular wilts attacking xylem -are the most harmful. Our knowledge about xylem anatomy and rewiring ability could bring the solutions against these diseases. In this review we summarize the recent findings on the molecular mechanisms of xylem formation with a special attention to the cellular changes, and cell wall rearrangements that are necessary to create functional capillaries. We emphasize the impact of abiotic factors and pathogens on xylem plasticity and discuss multidisciplinary approach to model xylem in crops.

Understanding the Root Xylem Plasticity for Designing Resilient Crops

Xylem is a main road in plant long-distance communication. Through xylem plants transport water, minerals and myriad of signaling molecules. With the onset during early embryogenesis, the development of xylem tissues relays on hormone gradients, activity of unique transcription factors, distribution of mobile miRNAs and receptor-ligand pathways. These regulatory mechanisms are often interconnected and all together contribute to the plasticity of water conducting tissue. Remarkably, root xylem carries water to all above-ground organs and therefore influences all aspects of plant growth. Because of the global warming and increasing water deficit, we need to come up with solutions for the crops of the future. It is clear that structure of water conducting elements directly impacts water transport within the plant. Among plant pathogens- vascular wilts attacking xylem -are the most harmful. Our knowledge about xylem anatomy and rewiring ability could bring the solutions against these diseases. In this review we summarize the recent findings on the molecular mechanisms of xylem formation with a special attention to the cellular changes, and cell wall rearrangements that are necessary to create functional capillaries. We emphasize the impact of abiotic factors and pathogens on xylem plasticity and discuss multidisciplinary approach to model xylem in crops.

Morphological cardiac changes in electrocution deaths: A literature review

Electrical injury may lead to damage to the conducting tissue, myocardial changes and even sudden cardiac death. Victims of low-voltage electrocution may have no electric marks, burns or other signs typical of electrical injuries. In these cases, the absence of other specific findings could make the identification of the cause of death very difficult. A broad spectrum of cardiac changes in cases of electrocution has been described in the literature, including the break-up of myocardial fibres, cardiomyolysis, haemorrhagic areas, the separation of myofibres and alternating hypercontracted–hyperdistended myocytes. All the described alterations, however, cannot be exclusively attributed to electrocution, since no specific morphological cardiac findings have so far been identified in electrocution. However, a few histological patterns recur, and their knowledge may be important for the forensic pathologist. This literature review describes the main pathological patterns observed in cases of fatal electrocution based on a literature search carried out up to September 2019 in the databases PubMed and Scopus. The search criteria included the keywords for cardiac lesions and electrocution. On the grounds of the literature data, a list of major and minor diagnostic markers for the passage of the electrical current through the heart tissue was created.

Presence of Polyphenols Complex Aromatic “Lignin” in Sargassum spp. from Mexican Caribbean

In recent years, the massive influx of pelagic Sargassum spp. has generated great interest in the scientific community, highlighting the urgency of addressing the physiology and biochemical composition of these species. Until now, the presence of lignified cells in the tissue of Sargassum natans and Sargassum fluitans has not been reported. Although ‘‘lignin-like’’ compounds have been identified in green algae, the presence of true lignin in the Sargassum genus has not been confirmed. Our work is the first report of lignified cells forming the secondary cell wall in these Sargassum. This study used histological techniques applied to thick sections for identifying lignin-like tissues in Sargassum spp. The dyes as Safranin O and Toluidine have been used to differentiate lignin and cellulose in conducting tissue and to indicate the presence, absence, and distribution of these compounds in tissues. This work is the initial study of the cell wall heteropolymers structure and arrangement in Sargassum spp., providing insights into the unique cell wall architecture of these seaweeds.

Stigma, pollen tube transmitting tract, and epidermal micromorphology of the style of Sarracenia purpurea (Sarraceniaceae)

Entomophilous flowers of the genus Sarracenia have a unique umbrella-shaped style, which consists of a broadened and flattened umbrella canopy and a thin cylindrical umbrella stalk. Anatomical and micromorphological features of the style of Sarracenia purpurea L. were studied using light microscopy and scanning electron microscopy. This study found that the pollen tube transmitting tracts (PTTTs) start as a semi-solid canal filled with endotrophic conducting tissue, and run from the peripheral to the center of the canopy where the PTTT becomes a hollow canal supported by ectotrophic conducting tissue. The presence of stomata on the epidermis of the canopy and chloroplasts in its ground parenchyma indicate photosynthetic activities. Convex epidermal cells with intense cuticular striations on the canopy that are similar yet different from those on various regions of the sepals and petals indicate that it may provide contrasting visual cues for pollinators. Multicellular secretory glands and trichomes, which may provide olfactory cues and tactical cues respectively, are also found on the canopy. Thus, the stylar umbrella not only serves as a region for pollen grain capture, pollen germination, and pollen tube transmission but may also play an important role during pollinator–flower interactions.

Influence of growing conditions on morphological and anatomical characteristics of pine needles in the northern taiga

The aim of the study was to determine the adaptive characteristics of pine needles associated with age and different growing conditions. The length of the needles decreases and its variability reduces with increasing dryness and poverty of the soil. In oppressed trees, the coefficient of variability of the length of the needles on the tree is 8%. The coefficient of variation in the length of needles approaching 20% will indicate the best conditions for the growth of a particular tree. Trends of the dependence of width and thickness of needles on growing conditions were not identified. The area of needles in pine forests with optimal water regime of soils (blueberry, cowberry type) varies in the range of 112–124 mm². In extreme growing conditions pine needles area is reduced by 27–33% and equals 76–86 mm². These ranges of values of the areas of needles are typical for plantings of the third and fourth classes of age. Changing the width and thickness of the needles is aimed at compensating for changes in the length of the needles in the direction of maintaining the optimal area for these conditions needles. In extreme conditions, the area of the assimilating tissue increases, and the area of the conducting tissue (stele) decreases. Correlation dependences of the area of the stele of needles with the cross-sectional area, with the area of conducting beams, with the number of resin canals and with the cover fabric are revealed.