Phloem Fibers Research Articles

A flax mutant with impaired intrusive growth of phloem and xylem fibres demonstrates constitutive gravitropic response

Intrusive growth is a type of growth in which a cell exceeds the growth rate of its neighbours and intrudes between them, reaching a much greater length. This process provides plant fibres with their exceptional length. Fibres are the most abundant cell type in the mechanical tissues of plants. At the same time, the plant fibres are of fundamental importance for the production of textiles, paper, biocomposites, etc. Here we describe a mutant of flax (reduced fibre 1, rdf) in which intrusive growth of fibres is impaired in both phloem and xylem. In addition to the intrinsic differences in fibre length, the mutant is characterized by a constitutive gravitropic response, mechanical aberrations at the macro- and nanolevels, disruption of the cambium and uneven transition of xylem cells to secondary cell wall formation. Gelatinous cell walls in both phloem and xylem of mutant plants have disturbed structure and reduced elasticity. The existence of this mutant-control pair offers both prospects for finding the molecular players involved in triggering intrusive growth, cell wall thickening and for understanding the principles of plant mechanical tissue functioning.

Overexpression of PeNAC122 gene promotes wood formation and tolerance to osmotic stress in poplars

Finding the adequate balance between wood formation and abiotic stress resistance is still an important challenge for industrial woody crops. In this study, PeNAC122, a member of the NAC transcription factor (TF) family highly expressed in xylem, was cloned from Populus euphratica. Tissue expression and β-glucuronidase (GUS) staining showed that PeNAC122 was exclusively expressed in phloem fiber and secondary xylem of stems. Subcellular and yeast transactivation assays confirmed that PeNAC122 protein existed in the nucleus and did not have transcriptional activation and inhibitory activity. Overexpression of PeNAC122 poplar lines exhibited reduced plant height, thickened xylem, and accumulated lignin content in stems, and also upregulates the expression of secondary cell wall biosynthetic genes. Moreover, overexpression of PeNAC122 lines displayed more tolerance to PEG6000-induced osmotic stress, with stronger photosynthetic performance, higher antioxidant enzyme activity, and less accumulation of reactive oxygen species in leaves, and higher expression levels of stress response genes DREB2A, RD29, and NCED3. These results indicate that PeNAC122 plays a crucial role in wood formation and abiotic stress tolerance, which, in addition to potential use in improving wood quality, provides further insight into the role of NAC family TFs in balancing wood development and abiotic stress resistance.

6-Benzylaminopurine and kinetin modulations during in vitro propagation of Quercus robur (L.): an assessment of anatomical, biochemical, and physiological profiling of shoots

For many woody species, such as Quercus robur, cytokinins in the culture medium are required to maintain in vitro plant material. Among synthetic cytokinins, 6-benzylaminopurine (BAP) and kinetin (KIN) are the most frequently used. In addition to inducing shoots, cytokinins can cause morphophysiological disorders. Therefore, we aimed to investigate the anatomical, biochemical, and physiological alterations and profiles of Q. robur shoots exposed to two cytokinins, applied alone and in combination. Shoots previously established in vitro were transferred to WPM culture media supplemented with BAP at concentrations of 0, 1.25, and 3.50 µM combined with KIN at concentrations of 0, 0.62, and 1.25 µM totaling 9 treatments. Anatomical, physiological, and biochemical analyses were performed after 40 days of culture. BAP induced the formation of new buds with anatomically underdeveloped leaves; induced shoot-tip necrosis, which is considered a response to the inefficient transport of water and nutrients; reduced the thickness of the cell walls of phloem fibers; and decreased the content of phenolic compounds and photosynthetic pigments. These responses were less pronounced with co-exposure to KIN. In contrast, KIN alone stimulated a larger area of secondary xylem and more lignified cell walls. BAP can induce shoots with underdeveloped anatomical and biochemical characteristics. Shoots that grew with KIN alone had stem and leaf anatomical characteristics, indicating greater commitment to cellular differentiation than proliferation. When both cytokinins are combined, KIN can partially mitigate the deleterious effects of BAP on in vitro growth. BAP generated shoots with underdeveloped anatomical and biochemical characteristics. KIN can partially mitigate the deleterious effects of BAP on in vitro growth.

Phytochemical and Physicochemical Analysis of the Invitro Antimicrobial and Antifungal Activities of Juglans Regia L. Bark (Walnut Bark)

Preliminary phytochemical and physicochemical screenings of Juglans regia are conducted to assure its purity, safety, and efficacy, as well as to determine the antibacterial and fungal activities and inhibitory zones of extracts against certain bacterial and fungal strains, with the aim of overcoming resistance. J. regia Linn, also known as akhrot in Pakistan, is a member of the Juglandaceae family, with a dense, long-lasting bark that is fragrant and resinous. The tree has a history of medical usage in the treatment of multiple ailments. The present research focuses on using preliminary phytochemical and physicochemical analyses to standardize Juglans regia Linn bark and to explore its antibacterial and antifungal activities. These analyses were conducted through microscopic analysis of the bark and determination of its quality parameters. Four different extracts of J. regia bark were tested for antimicrobial activity against a variety of harmful fungi and bacteria. Phytochemical analysis indicated the existence of reducing sugars, alkaloids, tannins, phenols, steroids, and saponins. Stone cells with sclereids, phloem fibers, oil cells, and lignified fibers are some of the observed microscopic characteristics of the powder. Antimicrobial analysis of J. regia bark extracts at concentrations of 300 and 400 µg/ml revealed that the ethanol and chloroform extracts had a considerable inhibitory effect on the development of pathogenic bacteria and fungi. This research will serve as a reference point for correctly identifying crude medications. It will also support the use of natural products as medications and validate the antibacterial and antifungal properties of J. regia (walnut bark) through clinical trials.

Pharmacognostic And Phytochemical Evaluation Of Cordia Obliqua Willd Fruits

Cordia (family Boraginaceae) is a genus of deciduous flowering trees or shrubs comprising more than 300 species distributed widely in the tropical regions. The aim of this research was to provide scientific information on phramacognostical nature and presence of various phytochemicals in the fruits of Cordia obliqua. The present study helped to evaluate anatomical, histochemical, physico chemical analysis and chemical tests of various extracts of Cordia obliqua willd fruits. Common names of plants are “Naruvili, Ali and Namaviri (Tamil), Lassura Viri, Cheruvari (Kerala). China-nakeru (Andhra and Telangana)”. It is considered as one of the most important medicinal plants and various plant parts like leaves, fruits, bark and seed were found to possess abundant ethno medicinal value. Most frequently they are used to treat many ailments such as respiratory disorders, stomach pain, wound, inflammation, myalgia, cough, dysentery and diarrhoea. The fruits are widely used for the treatment of spleen and hepatic disorders. The anatomical and histochemical characteristics of the fruits of Cordia obliqua have been studied which helped in authentication and diagnose the various anatomical characters like presence of epidermis, mucilage, xylem and phloem fibers and calcium oxalate crystals. Proximate analyses of fruits were performed which included moisture content, extractive values and ash values helped to identify the purity and solubility of fruits in different solvents which was revealed by extractive values. Chemical tests helped to know the various phytoconstituents present in the fruits of Cordia obliqua when tested with various chemical reagents. Phytochemical tests revealed the presence of steroids, glycosides, alkaloids, tannins, phenolic and flavonoid compounds and carbohydrates.

Anatomical Response of Regenerated Bark in Terminalia arjuna(Roxb.) Wight & Arn.

Terminalia arjuna is a large tropical tree whose both original and regenerated bark is commercially exploited for medicinal purpose Terminalia arjuna mainly to cure cardiac diseases. For sustainable supply of Arjuna bark, the regenerated bark of tree is usually harvested within 18-24 months with controlled wounding at different girth classes. During course of investigation, it was found that the biomass and rigidity of regenerated bark was higher than original bark in each girth-class of tree. To explore the reason for higher biomass and rigidity in the regenerated bark of , Arjunaa comparative anatomical investigation was carried out between original and regenerated bark from randomly selected trees of middle girthclass (50-75cm). Results showed that there was significantly higher proportion of phloem fibres and ray cells and lower proportion of sieve tubes in regenerated bark in comparison to original bark. Most of the fibre dimensions and ray parameters varied between original and regenerated bark and also between first and second harvest of the regenerated bark. The wounded tree gives first preference to the protection of the injured bark from surroundings rather than food conduction through sieve tubes.

Effects of different amounts of cellulase on the microstructure and soluble substances of cotton stalk bark

There are plant cuticle and complex cell walls on the outer surface of cotton stalk bark (CSB), which reduce the efficiency of liquid penetration of CSB. To increase the permeability of liquids, these barriers need to be broken. Cellulase can selectively hydrolyze cellulose into glucose, and its action conditions are mild. Therefore, cellulase treatment is one of the excellent ways to break the CSB liquid permeation barrier. This experiment studied the effects of different amounts of cellulase treatment on the enzymatic hydrolysis products and surface of CSB. Scanning electron microscopy (SEM) and nano-CT were used to observe the changes in the microscopic morphology of CSB. Ion chromatography and an ultraviolet–visible spectrophotometer were used to determine the dissolution of CSB. The results showed that the cuticle of CSB treated with cellulase was broken, and the cell wall of phloem fibers became thinner, which increased the accessibility of liquid. The content of monosaccharide and lignin in CSB treatment solution increased with the increase of cellulase dosage. Correspondingly, the proportion of polysaccharides on the outer surface of CSB continued to decline and eventually stabilized. These experimental results can provide a reference for improving the permeability of natural fibers and the subsequent treatment effects of biomass products.Graphical abstractThe pretreatment of cotton stalk barks with cellulase destroyed the dense protective structure of cell wall, and the content of monosaccharide and lignin in the treated solution increased with the increase of cellulase dosage.

Role of leaf fibro-vascular bundle configuration on feeding of <em>Deltocephalus menoni</em> (Hemiptera: Cicadellidae) in the transmission of White Leaf Disease in sugarcane varieties

Purpose: Deltocephalus menoni is the vector of Sugarcane White Leaf Disease (WLD) and the causative agent of White Leaf Disease Phytoplasma (WLDP). WLDP is restricted to the phloem tissues facilitating its dispersal via sap containing phytoplasma during the vector feeding. Here, the configuration of the vascular bundle would be an important characteristic in plant’s resistance to vector feeding and thereby the disease spread. A study was conducted to determine the relationship between feeding of D. menoni and the configuration of leaf fibro-vascular bundles. Research Method: Feeding amount of D. menoni on sugarcane varieties, the configuration of leaf fibro-vascular bundle of leaf blade in gross cross-section and the WLD infection in the natural environment were measured. Variations and correlations between configuration of leaf fibro-vascular bundles between varieties, vector feeding and WLD infection were studied. Major anatomical characteristics of vascular bundles that contribute to feeding were also determined. Findings: The structure of the leaf fibro-vascular bundles varied with the sugarcane variety/ accession and the volume of feeding by D. menoni of sugarcane was correlated with the configuration of the leaf fibro vascular bundle. Distance from the epidermis to vascular parenchyma, distance from epidermis to vascular bundle and thickness of phloem fiber layer were negatively correlated with the feeding amount of D. menoni. The size of phloem tubes, the width of the vascular bundle and the total number of vascular bundles, were positively correlated. The level of WLD infection in natural environment was also correlated with the structure of leaf fibro vascular bundle. Originality/value: Configuration of leaf fibro vascular bundles could be used to predict feeding of D. menoni, level of WLD infection, which could be incorporated into selection and directional breeding of sugarcane against the vector.

Morphology and Anatomy of Leaf, Stem and Petiole of Luvunga crassifolia Tanaka (Rutaceae)

Luvunga crassifolia is an underutilized plant in the Citrus family. Other than brief morphological descriptions, there are no published reports on other identification features of this plant. Thus, the current study was aimed to investigate macroscopic and microscopic diagnostic features of L. crassifolia leaves, stems, and petioles. Macroscopic characterization, optimization of histological procedure, and histochemical analyses of differential stains were carried out on the leaves, stems, and petioles of L. crassifolia. The histological method was optimized by modifying the following parameters: number of fixation days, dehydration duration with degraded series of ethanol or butanol, clearing duration, and infiltration duration. After infiltration, embedding and sectioning of the tissues were performed. Histochemical analyses were carried out using differential stains to identify the cellular components in leaf, stem and, petiole tissue sections. This study showed that L. crassifolia leaves are amphistomatic. Pellucid dots were observed on both adaxial and abaxial leaf surfaces. Secretory cavities, xylem, phloem, and pericyclic fibers were found in the cross-sections of leaf, stem, and petiole. Calcium oxalates were present in the leaf and stem sections, while trichomes were detected in stem and petiole sections. The information obtained from this study will be helpful for the identification and future taxonomic-related studies of this plant species.

Anatomy and cell wall ultrastructure of sunflower stalk rind

The anatomy and ultrastructure of sunflower stalk rind are closely related to its conversion and utilization. We studied systematically the anatomy and ultrastructure of the stalk rind using light, scanning electron, transmission electron and fluorescence microscopy. The results showed that the stalk rind consisted of phloem fibers (PF), xylem fibers (XF), vessel elements (V), ground parenchyma cells (GPC), axial parenchyma cells (APC), xylem ray parenchyma cells (XRPC), and pith ray parenchyma cells (PRPC). These cell walls were divided into the middle lamella, primary wall, and secondary wall (S). It was found that the S of PF, XF and V was further divided into three layers (S1–S3), while the S of APC, GPC, XRPC and PRPC showed a non-layered cell wall organization or differentiated two (S1, S2) to seven layers (S1–S7). Our research revealed the plasmodesmata characteristics in the pit membranes (PMs) between parenchyma cells (inter-GPCs, inter-XRPCs, and inter-PRPCs). The morphology of the plasmodesmata varied with the types of parenchyma cells. The thickness and diameter of PMs between the cells (inter-Vs, V–XF, V–APC, and V–XRPC) were greater than that of PMs between parenchyma cells. The cell corners among parenchyma cells were intercellular space. The lignification degree of vessels was higher than that of parenchyma cells and fibers. The results will provide useful insights into the biological structure, conversion and utilization of sunflower stalk rind.

Cellular and Metabolite Changes in the Secondary Phloem of Chinese Fir (Cuninghamia lanceolata (Lamb.) Hook.) during Dormancy Release

Wood in the cold temperate zone is the product of the alternation of the growing season and the dormant period of trees, but our knowledge of the process of dormancy release in trees remains limited. Chinese fir (Cuninghamia lanceolata (Lamb.) Hook.) was used to investigate cellular and metabolite changes in the secondary phloem tissue during dormancy release. The sampling dates were 2 March, 28 March, and 13 April. The microsections of wood-forming tissue were prepared using the paraffin embedding technique to observe the formation of cambium cells; metabolites in secondary phloem cells were extracted using a methanol/chloroform organic solvent system. The results showed that the secondary phloem consists of phloem fibers, sieve cells and phloem parenchyma. The cells were regularly arranged in continuous tangential bands and were in the order of Phloem fiber-Sieve cell-Phloem parenchyma-Sieve cell-Phloem parenchyma-Sieve cell-Phloem parenchyma-Sieve cell-Sieve cell-Phloem parenchyma-. The Chinese fir cambium was in dormancy on 2 March and 28 March, while on 13 April, it was already in the active stage and two layers of xylem cells with several layers of phloem cells were newly formed. The width of the cambium zone increased from 18.7 ± 5.7 μm to 76.5 ± 3.0 μm and the average radial diameter of sieve cells expanded from 15.4 ± 7.5 μm to 21.5 ± 7.4 μm after dormancy release. The cambium zone width and the average radial diameter of sieve cells before and after dormancy release were significantly different (p < 0.01). The phloem parenchyma cells without resin were squeezed and deformed by the sieve cells, and the width of the phloem during the active period was 197.0 ± 8.5 μm, which was larger than that during the dormant period. Ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS)-based metabolomics was employed to analyze the secondary phloem of Chinese fir on 28 March and 13 April. Thirty-nine differential metabolites during dormancy release were detected. The results showed that the composition of Chinese fir metabolites was different before and after dormancy release. The relative increase in pyruvic acid and ascorbic acid contents proved that the rate of energy metabolism in Chinese fir increased substantially after dormancy release. Changes in cell development and the composition of metabolites revealed that the dormancy release of Chinese fir was at early April and the formation period of phloem tissue is earlier than xylem tissue.

Pharmacognostic and Preliminary Phytochemical Investigation of stem of Conocarpus lancifolius

Aims: To evaluate pharmacognostic and preliminary phytochemical analysis of stem of Conocarpus lancifolius including macroscopic, microscopic and physicochemical parameters. Methods and Material: Macroscopic and microscopic properties of dried stem were investigated. Preliminary phytochemical analysis of various extracts and fluorescence analysis of dried stem powder was performed using various chemicals. Physicochemical parameters were evaluated as per WHO guidelines. Results: Organoleptic parameters of stem of C. lancifolius like colour, shape, size etc were noted. Transverse section of fresh stem revealed the presence of epidermis, cortex, sone cells, phloem, xylem and pith. Whereas, powder microscopy showed the presence of epidermis, xylem, stone cells, phloem fibre with crystals of calcium oxalate etc. Phytochemical screening of methanolic extract of stem showed presence of alkaloids, flavonoids, glycoside, steroids etc. Ethyl acetate extract showed the presence of alkaloids and steroids while aqueous extract showed presence of tannins. Physicochemical parameters viz. ash value, extractive value, moisture content, fluorescence analysis and foaming index of stem powder were determined. The total tannins were also determined in the stem of C. lancifolius. Conclusion: The present study revealed pharmacognostic and preliminary phytochemical parameters of stem of C. lancifolius which would be beneficial for its standardization and future scope of the work.

New insights into Chinese traditional handmade paper: influence of growth age on morphology and cellulose structure of phloem fibers from Pteroceltis tatarinowii

New insights into Chinese traditional handmade paper: influence of growth age on morphology and cellulose structure of phloem fibers from Pteroceltis tatarinowii

Tri-Trophic Relationship among Sugarcane White Leaf Disease Phytoplasma (WLDP), <em>Deltocephalus menoni</em> (Homoptera: Cicadellidae) and Sugarcane Plant in Secondary Transmission of the Disease

Purpose: Sugarcane White Leaf Disease (WLD) is one of the most devastative diseases in cane-sugar industry in Sri Lanka and the causative agent is a distinct phytoplasma (WLDP) strain within the 16SrXI. White Leaf Disease spreads through infected seed cane and insect vector; Deltocephalus menoni (Hemiptera: Cicadellidae). This paper presents the tri-trophic relationship of the plant, vector and pathogen in disease transmission. Research Method: Four-month-old sugarcane plants of the variety SL 96 128 and laboratory-reared populations of D. menoni were used for this study. Performance of D. menoni on healthy plants and WLD plants was examined in relation to the aggregation, amount of feeding, fecundity, number of nymphs emerged, nymphal period, survival of nymph and adult’s longevity. The plant architecture, leaf histological and physiological aspects were also studied. Findings: Except for nymphal period, all behavioural characteristics were significantly-high in WLDinfected plants in 10, 14, 30, 8, 12 and 17 percent, respectively. The nymphal period of D. menoni was significantly-reduced by 12.78 percent. Number of shoots (41.83 percent) and leaves (18.96 percent) were high and distance between two leaves tends to be reduced by 32.85 percent in diseased-plants altering plant architecture into a profuse and bushy nature. Sucking distance, thicknesses of lower epidermis and phloem fibre layer in leaves were significantly reduced in infected plants. Leaf N, P, K and moisture content increased (24.89, 34.78, 28.64 and 3.85percent) while leaf wax content was reduced by 4.93 percent. Originality/value: Disease infected plants are augmenting its vector; D. menoni by attracting, enhancing survival and population build-up which promotes the transmission of WLD phytoplasma itself. There by regular inspection and rogueing out of WLD infected clumps make a great impact on secondary transmission of WLD by D. menoni.

The thickening and modification of the galactan-enriched layer during primary phloem fibre development in Cannabis sativa.

Primary phloem fibres (PPFs) have higher fibre quality and are economically more important for the textile sector than secondary phloem fibres. Both the chemical composition and mechanical structure of the secondary cell wall mainly influence the quality of bast fibres. We investigated the thickening of the galactan-enriched (Gn) layer and its modification process into a gelatinous (G)-layer, which is the largest portion of the secondary cell wall, during the development of the PPF in Cannabis sativa. Stem segments of hemp collected at 17, 29, 52 and 62 days after sowing were comparatively examined using light microscopy, scanning electron microscopy and transmission electron microscopy. The initial cells of PPF started the proliferation and differentiation at 17 days, but the secondary cell wall thickening had already commenced before the 29 days. Both the G- and Gn-layer were rapidly added onto the S-layer of PPFs; thus, the secondary cell wall thickness increased approximately 2-fold at 52 days (from the 29-day mark), and 8-fold at 62 days. The cortical microtubule arrays appeared adjacent to the plasma membrane of PPF cells related to the cellulose synthesis. Additionally, cross-sectioned microfibrils were observed on Gn-layer as the cluster of tiny spots. At 62 days, the specific stratification structure consisting of several lamellae occurred on the G-layer of the secondary cell wall. The secondary cell wall thickened remarkably at 52 days through 62 days so that the mature secondary cell wall consisted of three distinctive layers, the S-, G- and Gn-layer. Cortical microtubule arrays frequently appeared adjacent to the plasma membrane together with cellulose microfibrils on secondary cell wall. The G-layer of PPF at 62 days exhibited the characteristic stratification structure, which demonstrates the modification of the Gn-layer into the G-layer.

Preparation, morphology and properties of biodegradable phloem fiber of alchornea davidii franch reinforced PBS composites

In this work, we use the treated PF-ADF(2 ∼ 3 mm) as the reinforcing body(fiber) and the biodegradable PBS as the matrix. The different treated PF-ADF were mixed with PBS particles according to the mass percentage of 20:80, and C-PBS, C-DF/PBS, C-ADF/PBS and C-KDF/PBS were prepared by molding process. The influence of surface treatment on the microstructure and physical properties of the fiber were discussed and the mechanical properties of the composites were compared. Also the biodegradability of the different composite was analyzed. The results showed that most of the non-cellulosic materials such as pectin were removed from C-DF, but a certain amount of pectin remains on the surface. The surface of C-ADF appeared ‘S’ groove, and the groove on C-KDF was good continuity and deep. Compared with C-DF, the tensile strength of C-ADF and C-KDF increased by 5.08% and decreased by 3.58% respectively. Compared with C-PBS, the tensile strength and bending strength of C-KDF/PBS increased by 48.32% and 25.97% respectively, and the tensile modulus and bending modulus increased by 146.45% and 128.3% respectively. The changes of biodegradability of C-DF/PBS, C-ADF/PBS and C-KDF/PBS composites were consistent, but the change of weightlessness rate of C-KDF/PBS was the smallest. The more degraded and uneven the surface of the composite, the more obvious the decrease in contact angle.

Functional understanding of secondary cell wall cellulose synthases in Populus trichocarpa via the Cas9/gRNA-induced gene knockouts.

Summary Plant cellulose is synthesized by a large plasma membrane‐localized cellulose synthase (CesA) complex. However, an overall functional determination of secondary cell wall (SCW) CesAs is still lacking in trees, especially one based on gene knockouts.Here, the Cas9/gRNA‐induced knockouts of PtrCesA4, 7A, 7B, 8A and 8B genes were produced in Populus trichocarpa. Based on anatomical, immunohistochemical and wood composition evidence, we gained a comprehensive understanding of five SCW PtrCesAs at the genetic level.Complete loss of PtrCesA4, 7A/B or 8A/B led to similar morphological abnormalities, indicating similar and nonredundant genetic functions. The absence of the gelatinous (G) layer, one‐layer‐walled fibres and a 90% decrease in cellulose in these mutant woods revealed that the three classes of SCW PtrCesAs are essential for multilayered SCW structure and wood G‐fibre. In addition, the mutant primary and secondary phloem fibres lost the n(G + L)‐ and G‐layers and retained the thicker S‐layers (L, lignified; S, secondary). Together with polysaccharide immunolocalization data, these findings suggest differences in the role of SCW PtrCesAs‐synthesized cellulose in wood and phloem fibre wall structures.Overall, this functional understanding of the SCW PtrCesAs provides further insights into the impact of lacking cellulose biosynthesis on growth, SCW, wood G‐fibre and phloem fibre wall structures in the tree.

Foliar anatomy of some Prunus L. subgen. Cerasus Mill. (Rosaceae) taxa

Prunus L. subgen. Cerasus Mill. (Rosaceae) contains numerous economically important species, including fruit trees and ornamental plants. This study compares the leaf anatomy and calcium oxalate crystal types of 98 individuals of 14 Prunus subgen. Cerasus taxa from Turkey. We stained leaf sections with Safranin‐Alcian Blue double stain and mapped calcium oxalate crystals under light microscope with polarized light. We used one‐way ANOVA to determine the statistical significance of quantitative data. Significant quantitative and qualitative data were analyzed using PCoA to establish relationships among taxa. We observed three different crystal distribution patterns and three crystal types, finding druses present in all taxa, while some taxa also have sand or prismatic forms. Most characters showed high variation. Our analysis shows that vascular bundle, midrib, upper epidermis and lower epidermis width/length ratios; midrib epidermis, upper epidermis and phloem cell lengths; upper epidermis and lower epidermis cell widths and lower cuticle thickness are not taxonomically useful, while features of the bundle sheath, epidermis cell surface, phloem fibers, mesophyll layers and angle of blade between the midrib can be used in conjunction with other characters to distinguish certain taxa. Overall, PCoA delineated two rough groups, separating P. avium, P. cerasus and P. mahaleb from the rest of the studied taxa. In investigating the anatomical variation between different individuals of these taxa, we found that some features previously used in infraspecific taxa, such as trichomes, varied sometimes even within an individual, casting doubt on the wisdom of using these for systematic work in subgenus Cerasus.

Tissue-specific metabolite profiling of Fallopia multiflora (Heshouwu) and Fallopia multiflora var. angulata by mass spectrometry imaging and laser microdissection combined with UPLC-Q/TOF-MS

Heshouwu, derived from root tubers of Fallopia multiflora (Thunb.) Harald., is a well-known herb used for millennia in traditional Chinese medicine. However, different forms of root tubers of Heshouwu have occurred in current Chinese herbal market and used in clinic, although it is still unknown whether their quality is consistent. In the present study, a mass spectrometry imaging and laser microdissection combined with UPLC-Q/TOF-MS were therefore used for the metabolite profiling on the whole and different parts of root tubers of F. multiflora and F. multiflora var. angulata. Our results suggested that the character of “woody heart” root tubers of F. multiflora was similar to that of F. multiflora var. angulata, but the latter had more phloem fibers and larger diameter vessel in the normal vascular bundle. Moreover, 140 compounds including stilbenes, anthraquinones, phenolic acids, naphthalenes, and other compounds were identified or putatively characterized from F. multiflora and F. multiflora var. angulata. Both unsupervised principal component analysis (PCA) and supervised Orthogonal Partial Least Squares Discrimination Analysis (OPLS-DA) multivariate statistics allowed discriminating F. multiflora and F. multiflora var. angulata. And a total of 32 potential markers were identified. The tissue-specific study indicated that the compounds in the phelloderm of F. multiflora and F. multiflora var. angulata were the most abundant. This is the first study on metabolite profiling and comparison of root tubers between F. multiflora and F. multiflora var. angulata, which would provide reasonable basis for further quality evaluation and safe medication of F. multiflora.

Cell Wall Layer Induced in Xylem Fibers of Flax Upon Gravistimulation Is Similar to Constitutively Formed Cell Walls of Bast Fibers.

In the fibers of many plant species after the formation of secondary cell walls, cellulose-enriched cell wall layers (often named G-layers or tertiary cell walls) are deposited which are important in many physiological situations. Flax (Linum usitatissimum L.) phloem fibers constitutively develop tertiary cell walls during normal plant growth. During the gravitropic response after plant inclination, the deposition of a cellulose-enriched cell wall layer is induced in xylem fibers on one side of the stem, providing a system similar to that of tension wood in angiosperm trees. Atomic force microscopy (AFM), immunochemistry, and transcriptomic analyses demonstrated that the G-layer induced in flax xylem fibers was similar to the constitutively formed tertiary cell wall of bast (phloem) fibers but different from the secondary cell wall. The tertiary cell walls, independent of tissue of origin and inducibility, were twice as stiff as the secondary cell walls. In the gravitropic response, the tertiary cell wall deposition rate in xylem was higher than that of the secondary cell wall. Rhamnogalacturonan I (RG-I) with galactan side chains was a prominent component in cellulose-rich layers of both phloem and xylem flax fibers. Transcriptomic events underlying G-layer deposition in phloem and xylem fibers had much in common. At the induction of tertiary cell wall deposition, several genes for rhamnosyltransferases of the GT106 family were activated in xylem samples. The same genes were expressed in the isolated phloem fibers depositing the tertiary cell wall. The comparison of transcriptomes in fibers with both inducible and constitutive tertiary cell wall deposition and xylem tissues that formed the secondary cell walls is an effective system that revealed important molecular players involved in the formation of cellulose-enriched cell walls.