Sieve Elements Research Articles

Evaluation of the Performance of a Composite Water Control Process for Offshore Bottom Water Fractured Gas Reservoirs

Natural gas, as one of the main energy sources of the modern clean energy system, is also an important raw material for the chemical industry, and the stable extraction of natural gas reservoirs is often affected by bottom water. It is difficult to control water in natural gas reservoirs, while fractured gas reservoirs are even more demanding. This is due to the complexity of the seepage laws of gas and water in fractures, resulting in the poor applicability of conventional processes for water control. Continuous research is needed to propose a process with effective control capabilities for bottom-water fractured gas reservoirs. Aiming at the above difficulties, this paper is based on a large-scale three-dimensional physical simulation device to carry out physical model design and simulation results testing and analysis. The water control ability of the combination of density-segmented sieve tubes and continuous packers in fractured gas reservoirs is explored. The physical simulation results show that the fracture distribution characteristics control the upward transportation path of bottom water. According to the segmentation characteristics of the fractures at the horizontal section location, optimizing the number of horizontal well screen tube segments and the density of boreholes reduces the cone-in velocity of bottom water before connecting the fractures to a certain extent. And the combined process has different degrees of water control ability for the three stages of bottom water transportation from the fractured gas reservoir to the production well. As the degree of water in the production well increases, the water control ability of the process gradually decreases. After the implementation of the water control process, the water-free gas production period was extended by about 6.84%, and the total production time was extended by about 6.46%. After the shutdown of the horizontal wells, the reduction in daily water production can still reach 21% compared to the natural extraction. The results of this research can provide process suggestions for water control in offshore fractured reservoirs and further ensure stable production in offshore fractured gas reservoirs.

First report of 'Candidatus Phytoplasma asteris' associated with witches'-broom disease of Pinus yunnanensis in China.

Pinus yunnanensis is an evergreen tree belonging to Pinaceae. The species is distributed in the east of Tibet, southwest of Sichuan, southwest of Yunnan, southwest of Guizhou and northwest of Guangxi. It is an indigenous and pioneer tree species for barren mountain afforestation in southwest China. P. yunnanensis has important value to both the building and medicine industries (Liu et al. 2022). In May 2022, P. yunnanensis showing witches'-broom symptom were found in Panzhihua City, Sichuan Province, China. The symptomatic plants had yellow or red needle, and exhibited plexus bud and needle wither. The lateral buds of infected pines developed into twigs. Some lateral buds grew in clusters and a few sprouted needles (Fig.1). The disease was named the P. yunnanensis witches'-broom disease (PYWB) and was found in some areas of Miyi, Renhe, and Dongqu. More than 9% of the pines showed these symptoms in the three areas surveyed, and the disease was spreading. A total of 39 samples were collected from three areas, including 25 symptomatic plants and 14 asymptomatic plants, respectively. The lateral stem tissues of 18 samples were observed under a scanning electron microscope (Hitachi S-3000N). Spherical bodies were found in the phloem sieve cells of symptomatic pines (Fig.1). Total DNA was extracted from 18 plant samples using the CTAB method (Porebski et al. 1997) and subjected to nested-PCR testing. Double-distilled water and DNA extracted from asymptomatic plants were used as negative controls, and DNA extracted from Dodonaea viscosa affected by the D. viscosa witches'-broom disease was used as positive control. Nested PCR was employed to amplify the pathogen's 16S rRNA gene (Lee et al. 1993; Schneider et al. 1993) and 1.2 kb segment were produced (GenBank accessions OP646619; OP646620; OP646621). PCR specific to the ribosomal protein (rp) gene yielded segment of approximately 1.2 kb (Lee et al. 2003)(GenBank accessions OP649589; OP649590; OP649591). The fragment size from 15 samples was consistent with the positive control, confirming the association of phytoplasma with the disease. A BLAST analysis of the 16S rRNA sequences of P. yunnanensis witches'-broom phytoplasma showed that it shared 99.12% ~99.76% identity with that of Trema laevigata witches'-broom phytoplasma (GenBank accession MG755412). The rp sequence shared 99.84%~99.92% identity with that of Cinnamomum camphora witches'-broom phytoplasma (GenBank accession OP649594). An analysis with iPhyClassifier (Zhao et. 2013) showed that the virtual RFLP pattern derived from OP646621 16S rDNA fragment of PYWB phytoplasma is identical (similarity coefficient 1.00) to the reference pattern of 16Sr group I, subgroup B (OY-M, GenBank accession AP006628). The phytoplasma is identified as a 'Candidatus Phytoplasma asteris'-related strain belonging to sub-group 16SrI-B. Interestingly, compared to AP006628, the virtual RFLP pattern derived from OP646619 and OP646620 fragments exhibit differences in three and one cleavage site, with a similarity coefficient of 0.92 and 0.97, respectively (Fig.2). These strains may represent a new subgroup within the 16Sr group I. The phylogenetic tree was reconstructed based on 16S rRNA and rp gene sequences using MEGA versio6.0 (Tamura et al. 2013). The analysis was conducted using the neighbor-joining (NJ) method with 1,000 replicates of bootstrap analysis. The results indicated that the PYWB phytoplasmas grouped into clades including phytoplasmas belonging to 16SrI-B and rpI-B, respectively (Fig.3). In addition, 2-year-old P. yunnanensis were used for grafting assays in nursery, and the twigs from infected pine under natural conditions were used as a scion, and the phytoplasma were detected using nested PCR after grafting for 40 d (Fig.4). In 2008-2014, P. sylvestris and P. mugo in Lituania had excessive branching symptoms that were attributed to 'Ca. Phtyoplasma Pini' (16SrXXI-A) or asteris' (16SrI-A) strains (Valiunas et al. 2015). In 2015, P. pungens with abnormal shoot branching in Maryland were found to be infected by 'Ca. Phytoplasma pini' strain (16SrXXI-B) (Costanzo et al. 2016). To the best of our knowledge, P. yunnanensis is a new host of 'Ca. Phytoplasma asteris'-related strain (16SrI-B) in China. The newly emerged disease is a threat to pines.

First report of 'Candidatus Phytoplasma asteris' associated with yellowing, scorching and decline of almond trees in India.

The almond, a commercially important tree nut crop worldwide, is native to the Mediterranean region. Stone fruit trees are affected by at least 14 'Candidatus Phytoplasma' species globally, among which 'Candidatus Phytoplasma asteris' is one of the most widespread phytoplasma infecting Prunus dulcis, causing aster yellows disease. Recently, almond plantations of Nauni region were consistently affected by phytoplasma, as evidenced by visible symptoms, fluorescent microscopic studies and molecular characterization. During several surveys from May to September 2020-2022, almond aster yellows phytoplasma disease showing symptoms such as chlorosis, inward rolling, reddening, scorching and decline with an incidence as high as 40%. Leaf samples were collected from symptomatic almond trees and the presence of phytoplasma was confirmed through fluorescent microscopic studies by employing DAPI (4, 6-diamino-2-phenylindole) that showed distinctive light blue flourescent phytoplasma bodies in phloem sieve tube elements. The presence of phytoplasma in symptomatic almond trees was further confirmed using nested PCR with specific primer pairs followed by amplification of 16S rDNA and 16S-23S rDNA intergenic spacer (IS) fragments. Sequencing and BLAST analysis of expected amplicon of the 16S rDNA gene confirmed that the almond phytoplasma in Himachal Pradesh was identical to the aster yellows group phytoplasma. Phylogenetic analysis of 16S rDNA almond phytoplasma also grouped 'Prunus dulcis' aster yellows phytoplasma within 16SrI-B subgroup showed 94% nucleotide identity with 'Prunus dulcis' phytoplasma PAEs3 and 'Prunus dulcis' phytoplasma PAE28 from Iran. This research presents the first host report of 'Candidatus Phytoplasma asteris' infecting almonds in India, expanding the knowledge of the diversity and distribution of phytoplasma strains affecting almond trees globally.

The Interplay between Enucleated Sieve Elements and Companion Cells.

In order to adapt to sessile life and terrestrial environments, vascular plants have developed highly sophisticated cells to transport photosynthetic products and developmental signals. Of these, two distinct cell types (i.e., the sieve element (SE) and companion cell) are arranged in precise positions, thus ensuring effective transport. During SE differentiation, most of the cellular components are heavily modified or even eliminated. This peculiar differentiation implies the selective disintegration of the nucleus (i.e., enucleation) and the loss of cellular translational capacity. However, some cellular components necessary for transport (e.g., plasmalemma) are retained and specific phloem proteins (P-proteins) appear. Likewise, MYB (i.e., APL) and NAC (i.e., NAC45 and NAC86) transcription factors (TFs) and OCTOPUS proteins play a notable role in SE differentiation. The maturing SEs become heavily dependent on neighboring non-conducting companion cells, to which they are connected by plasmodesmata through which only 20-70 kDa compounds seem to be able to pass. The study of sieve tube proteins still has many gaps. However, the development of a protocol to isolate proteins that are free from any contaminating proteins has constituted an important advance. This review considers the very detailed current state of knowledge of both bound and soluble sap proteins, as well as the role played by the companion cells in their presence. Phloem proteins travel long distances by combining two modes: non-selective transport via bulk flow and selective regulated movement. One of the goals of this study is to discover how the protein content of the sieve tube is controlled. The majority of questions and approaches about the heterogeneity of phloem sap will be clarified once the morphology and physiology of the plasmodesmata have been investigated in depth. Finally, the retention of specific proteins inside an SE is an aspect that should not be forgotten.

Enhancement patterns of potassium on nitrogen transport and functional genes in cotton vary with nitrogen levels

The application of potassium (K) in conjunction with nitrogen (N) has been shown to enhance N use efficiency. However, there is still a need for further understanding of the optimal ratios and molecular regulatory mechanisms, particularly in soil-cotton systems. Here, a field trial was conducted, involving varying rates of N and K, alongside pot and hydroponic experiments. The objective was to assess the impact of N-K interaction on the absorption, transport and distribution of N in cotton. The results showed that K supply at 90 and 240 kg ha−1 had a beneficial impact on N uptake and distribution to both seed and lint, resulting in the highest N use efficiency ranging from 22% to 62% and yield improvements from 20% to 123%. The increase in stem and root diameters, rather than the quantify of xylem vessels and phloem sieve tubes, facilitated the uptake and transport of N due to the provision of K. At the molecular level, K supply upregulated the expression levels of genes encoding GhNRT2.1 transporter and GhSLAH3 channel in cotton roots to promote N uptake and GhNRT1.5/NPF7.3 genes to transport N to shoot under low-N conditions. However, under high-N conditions, K supply induced anion channel genes (GhSLAH4) of roots to promote N uptake and genes encoding GhNRT1.5/NPF7.3 and GhNRT1.8/NPF7.2 transporters to facilitate NO3- unloading from xylem to mesophyll cell in high-N plants. Furthermore, K supply resulted in the upregulation of gene expression for GhGS2 in leaves, while simultaneously downregulating the expression of GhNADH-GOGAT, GhGDH1 and GhGDH3 genes in high-N roots. The enzyme activities of nitrite reductase and glutamine synthetase increased and glutamate dehydrogenase decreased, but the concentration of NO3- and soluble protein exhibited a significant increase and free amino acid decreased in the shoots subsequent to K supply.

Characteristics of push valve centrifugal tray; a novel tray with pipe type downcomer

ABSTRACT The intention of providing this paper is to conduct an experimental investigation into the hydrodynamics of the push valve centrifugal tray, which has a new configuration, in order to retrofit the purpose of a stripper oil sweeting of Lavan oil manufacture. Experiments were performed on the commercial scale column by an air-water simulator rig. Two different pilot plants with 1.2 m and 3 m diameter have been used for experiments. Dry pressure drop, total pressure drop, and weeping data are presented on the commercial scale 1.2 m diameter column. The results compared with a sieve tray. Some correlations for the pressure drop and the weeping are presented. A pilot plant with a large diameter, 3 m, was also installed to predict the pressure drop with the exact characterization as the stripper column of Lavan oil manufacture to predict its pressure drop. The experiments were carried out in two different outlet weir heights, 0, 3 cm, and 2- and 4%-holes areas at various operating conditions. This article also introduced a new downcomer and tray design of the centrifugal tray. Experiments and industrial reports of this type of centrifugal tray show that it can be used in revamping and retrofit projects.

Cellular structure and property relationship of bamboo under transverse compression

Transverse compression of bamboo occurs during manufacturing of engineered bamboo products and densified bamboo, as well as in service under compressive-loading in structures. This study investigates the transverse compression behavior of Moso bamboo and the relationship of its compression modulus with density, and provides microscopic observations of the changing cellular structure during transverse loading. When compared to softwood of same density, bamboo shows higher compression modulus and yield strength. Bamboo’s matrix (parenchyma cells, vessels and sieve tubes) resembles a closed cell foam in transverse compression, presenting high density variation among specimens and plays an important role in its overall density, behavior and compression modulus. Bamboo’s behavior and compression moduli are also influenced by tissue density and its natural fiber reinforced composite structure. A refined model is required and presented which captures the non-linear stress-strain behavior of bamboo considering these characteristics. The model works in a range of densities in Moso bamboo and provides accurate prediction of its transverse compression behavior and magnitude.

Jujube witches' broom phytoplasmas inhibit ZjBRC1-mediated abscisic acid metabolism to induce shoot proliferation.

Jujube witches' broom (JWB) phytoplasmas parasitize the sieve tubes of diseased phloem and cause an excessive proliferation of axillary shoots from dormant lateral buds to favour their transmission. In previous research, two JWB effectors, SJP1 and SJP2, were identified to induce lateral bud outgrowth by disrupting ZjBRC1-mediated auxin flux. However, the pathogenesis of JWB disease remains largely unknown. Here, tissue-specific transcriptional reprogramming was examined to gain insight into the genetic mechanisms acting inside jujube lateral buds under JWB phytoplasma infection. JWB phytoplasmas modulated a series of plant signalling networks involved in lateral bud development and defence, including auxin, abscisic acid (ABA), ethylene, jasmonic acid, and salicylic acid. JWB-induced bud outgrowth was accompanied by downregulation of ABA synthesis within lateral buds. ABA application rescued the bushy appearances of transgenic Arabidopsis overexpressing SJP1 and SJP2 in Col-0 and ZjBRC1 in the brc1-2 mutant. Furthermore, the expression of ZjBRC1 and ABA-related genes ZjHB40 and ZjNCED3 was negatively correlated with lateral main bud outgrowth in decapitated healthy jujube. Molecular evidence showed that ZjBRC1 interacted with ZjBRC2 via its N-terminus to activate ZjHB40 and ZjNCED3 expression and ABA accumulation in transgenic jujube calli. In addition, ZjBRC1 widely regulated differentially expressed genes related to ABA homeostasis and ABA signalling, especially by binding to and suppressing ABA receptors. Therefore, these results suggest that JWB phytoplasmas hijack the ZjBRC1-mediated ABA pathways to stimulate lateral bud outgrowth and expansion, providing a strategy to engineer plants resistant to JWB phytoplasma disease and regulate woody plant architecture to promote crop yield and quality.

Climatic responses and variability in bark anatomical traits of 23 Picea species.

In woody plants, bark is an important protective tissue which can participate in photosynthesis, manage water loss, and transport assimilates. Studying the bark anatomical traits can provide insight into plant environmental adaptation strategies. However, a systematic understanding of the variability in bark anatomical traits and their drivers is lacking in woody plants. In this study, the bark anatomical traits of 23 Picea species were determined in a common garden experiment. We analyzed interspecific differences and interpreted the patterns in bark anatomical traits in relation to phylogenetic relationships and climatic factors of each species according to its global distribution. The results showed that there were interspecific differences in bark anatomical traits of Picea species. Phloem thickness was positively correlated with parenchyma cell size, possibly related to the roles of parenchyma cells in the radial transport of assimilates. Sieve cell size was negatively correlated with the radial diameter of resin ducts, and differences in sieve cells were possibly related to the formation and expansion of resin ducts. There were no significant phylogenetic signals for any bark anatomical trait, except the tangential diameter of resin ducts. Phloem thickness and parenchyma cell size were affected by temperature-related factors of their native range, while sieve cell size was influenced by precipitation-related factors. Bark anatomical traits were not significantly different under wet and dry climates. This study makes an important contribution to our understanding of variability in bark anatomical traits among Picea species and their ecological adaptations.

Caveolae-mediated endocytosis pathway regulates endothelial fenestra homeostasis in the rat pituitary

Endothelial fenestrae are transcellular pores separated by diaphragms formed by plasmalemma vesicle-associated proteins (PLVAP) and function as channels for peptide hormones and other substances. Caveola, a key regulator of clathrin-independent endocytosis, may be involved in the invagination and fusion of plasma membranes, which are essential for fenestra formation. In this study, we first found that caveolin-1 and -2, the major components of caveolae, was localized in fenestrated endothelial cells in the anterior lobe of the rat pituitary by immunohistochemistry. As we also observed caveolae in the endothelial cells of the anterior lobe of the rat pituitary by transmission electron microscopy, we studied the relationship between the caveolae-mediated endocytosis pathway and fenestrae structure in cultured endothelial cells isolated from the anterior lobe of the rat pituitary (CECAL) by immunofluorescence staining and scanning electron microscopy. The inhibition of caveolae-mediated endocytosis by genistein enlarged the PLVAP-positive oval-shaped structure that represented the sieve plate and induced the formation of a doughnut-shaped bulge around the fenestra in CECAL. In contrast, the acceleration of caveolae-mediated endocytosis by okadaic acid induced the diffusion of PLVAP-positive signals in the cytoplasm and reduced the number of fenestrae in CECAL. These results indicate that the caveolae-mediated endocytosis pathway is involved in the fenestra homeostasis in the fenestrated endothelial cells of the rat pituitary.

Design of a sieve tray tower for ammonia absorption

Las columnas de bandejas son esencialmente cilindros verticales en los cuales el líquido y el gas son puestos en contacto en operación por etapas en platos, y son útiles para procesos de absorción y destilación. En el presente artículo se llevó a cabo el diseño de una columna de bandejas perforadas para la absorción física de amoníaco usando agua como solvente. Los valores calculados del diámetro de la columna, caída de presión del gas por bandeja, caudal másico de arrastre y la eficiencia de la bandeja de Murphree corregida para arrastre fueron de 0,962 m; 0,683 kPa/bandeja; 0,102 kg/s y 0,796 respectivamente. Los valores calculados de tanto la caída de presión del gas por bandeja y el caudal másico de arrastre son menores que los límites establecidos por el proceso; por tanto, la columna de bandejas perforadas diseñada puede ser empleada satisfactoriamente para el servicio de transferencia de masa requerido.

Separation of Rare Earth Elements in Multistage Extraction Columns in Chromatography Mode: Experimental Study and Mathematical Simulation

The application of liquid–liquid chromatography principles to solvent extraction processes in hydrometallurgy can greatly simplify rare earth metal separation technologies by separating multicomponent mixtures in one technological operation. In this study, the chromatographic separation of rare earth elements (REEs) in multistage extraction columns was experimentally studied under conditions of impulse sample injection—single and multiple loading of large volumes of metal salt solution into the installation. The results obtained showed the feasibility of operating sieve plate extraction columns in the liquid–liquid chromatography mode. A closed-loop recycling technology is proposed for the separation of rare earth elements in multistage extraction columns operating in the liquid–liquid chromatography mode. For further development and industrial implementation of this technology, experimental studies should be conducted on intensified multistage extraction columns, such as sectioned columns with agitators and vibrating plate columns. Computer simulation of the chromatographic separation of rare earth elements by closed-loop recycling liquid–liquid chromatography was carried out.

The CLE33 peptide represses phloem differentiation via autocrine and paracrine signaling in Arabidopsis

Plant meristems require a constant supply of photoassimilates and hormones to the dividing meristematic cells. In the growing root, such supply is delivered by protophloem sieve elements. Due to its preeminent function for the root apical meristem, protophloem is the first tissue to differentiate. This process is regulated by a genetic circuit involving in one side the positive regulators DOF transcription factors, OCTOPUS (OPS) and BREVIX RADIX (BRX), and in the other side the negative regulators CLAVATA3/EMBRYO SURROUNDING REGION RELATED (CLE) peptides and their cognate receptors BARELY ANY MERISTEM (BAM) receptor-like kinases. brx and ops mutants harbor a discontinuous protophloem that can be fully rescued by mutation in BAM3, but is only partially rescued when all three known phloem-specific CLE genes, CLE25/26/45 are simultaneously mutated. Here we identify a CLE gene closely related to CLE45, named CLE33. We show that double mutant cle33cle45 fully suppresses brx and ops protophloem phenotype. CLE33 orthologs are found in basal angiosperms, monocots, and eudicots, and the gene duplication which gave rise to CLE45 in Arabidopsis and other Brassicaceae appears to be a recent event. We thus discovered previously unidentified Arabidopsis CLE gene that is an essential player in protophloem formation.

The Phloem: A Case of Theory Against Experiment

AbstractThe history of the long‐distance transport systems of vascular plants, phloem, and xylem, is a long and winding road of scientific progress which fascinated and occupied foresters, botanists, and physicists during the last 250 years. Although the Münch pressure flow hypothesis of phloem transport is meanwhile generally accepted, some details are not yet really understood. This pertains especially to the sieve plates whose function within the sieve tubes is controversially debated. Recently, Nakad et al. (2023, https://doi.org/10.1029/2022jg007361) contributed a fresh interpretation of the sieve plates based on a simple experimental setup which allowed to study their effect on phloem flow.

First report of 'Candidatus Phytoplasma asteris' associated with witches'-broom disease of Cinnamomum camphora in China.

Camphor tree (Cinnamomum camphora) has a wide distribution in the world and is mainly distributed in the South and southwest in China. It can be used as both a wood and a medicine, with high value in industry, medicine, and ecology. In May 2022, it was observed that the approximately ten to fifteen years old Camphor trees were exhibiting witches'-broom, small leaf morphology and chlorosis, and leaf drop in Panzhihua City, Sichuan Province, China. The witches'-broom symptoms consisted of many small branches with little leaves at the top of branches. It was named C. camphora witches'-broom disease (CCWB) and was found in some areas of Miyi, Yanbian, Renhe Xiqu and Dongqu counties. More than 28% of the plants were infected on the five areas surveyed. Total 100 samples were collected from five areas, with 15 symptomatic plants and 5 asymptomatic plants each area. The lateral stem tissues were observed under a scanning electron microscope (Hitachi S-3000N). The nearly spherical bodies were found in the phloem sieve cells of symptomatic plants. Total DNA extraction was conducted from 0.1 g tissue using the CTAB method (Porebski et al. 1997), ddH2O was used as the negative control, and Dodonaea viscose witches'-broom disease plants were used as the positive control. The nested PCR was employed to amplify the 16S rRNA gene (Lee et al. 1993; Schneider et al. 1993) and PCR amplicon of 1.2 kb were amplified (GenBank accessions OP662614; OP662615; OP662616). The direct PCR specific to the ribosomal protein (rp) gene yielded amplicons of approximately 1.2 kb with primer pair rp(I)F1A and rp(I)R1A (Lee et al. 2003) (GenBank accessions OP649592; OP649593; OP649594). The fragment from 25 symptomatic samples was consistent with the positive control, and asymptomatic plants were negative, confirming an association of a phytoplasma with the disease. A BLAST analysis of the 16S rRNA sequences of CCWB phytoplasma showed that it has a 99.44% similarity with Trema laevigata witches'-broom phytoplasma (GenBank accession MG755412). The rp sequence shared 99.59% identity with rapeseed phyllody phytoplasma (GenBank accession CP055264). An analysis with iPhyClassifier showed that the virtual RFLP pattern derived from the query 16S rDNA fragment of CCWB phytoplasma is most similar to the reference pattern of the 16Sr group I, subgroup B (OY-M, GenBank accession AP006628). The phytoplasma is identified as 'Ca. Phytoplasma asteris'-related strain belonging to sub-group 16SrI-B. The phylogenetic tree was constructed based on 16S rRNA gene and rp gene sequences by using MEGA version 6.0 (Tamura et al. 2013) with neighbor-joining (NJ) method and bootstrap support was estimated with 1000 replicates. The result indicated that the CCWB phytoplasma formed a subclade in 16SrI-B and rpI-B respectively. In addition, the plants were positive for the phytoplasma using nested PCR after grafting for 30 d in nursery conditions. It is noteworthy that the plants were seriously damaged by aphid, Psyllidae and Ceroplastes. It is speculated that the insects of Homoptera typically transmit phytoplasmas by feeding on plant sap, thus it is necessary to control aphids in order to control the C. camphora witches'-broom disease. To the best of our knowledge, Camphor tree is a new host plant of 'Ca. Phytoplasma asteris' in China. The newly emerged disease is a threat to Camphor tree production.

The multifarious role of callose and callose synthase in plant development and environment interactions.

Callose is an important linear form of polysaccharide synthesized in plant cell walls. It is mainly composed of β-1,3-linked glucose residues with rare amount of β-1,6-linked branches. Callose can be detected in almost all plant tissues and are widely involved in various stages of plant growth and development. Callose is accumulated on plant cell plates, microspores, sieve plates, and plasmodesmata in cell walls and is inducible upon heavy metal treatment, pathogen invasion, and mechanical wounding. Callose in plant cells is synthesized by callose synthases located on the cell membrane. The chemical composition of callose and the components of callose synthases were once controversial until the application of molecular biology and genetics in the model plant Arabidopsis thaliana that led to the cloning of genes encoding synthases responsible for callose biosynthesis. This minireview summarizes the research progress of plant callose and its synthetizing enzymes in recent years to illustrate the important and versatile role of callose in plant life activities.

Study on the flow structures and distribution law of rotational–perforated coupling flow in tridimensional rotational flow sieve tray

Tridimensional rotational flow sieve trays (TRST) have a variety of gas–liquid flow structures, such as rotational flow, flow through one perforation and flow through two perforations, it is important to have a deep understanding of the coupling and distribution laws of rotational flow and flow through perforations for the selection and regulation of actual working conditions. In this study, the flow structures and proportions for the rotational–perforated coupling flow in a TRST were analyzed and predicted using the measured distribution ratio for the three-blade unit. The results showed that the gas phase mainly flowed in a rotational pattern, and its proportion was approximately 62%–83%. The proportion of flow through perforations in the liquid phase was relatively large, and the proportion of flow through one perforation was approximately 51%–57%. The proportion of flow through two perforations was approximately 27%–29%.

Phloem development.

The evolution of the plant vascular system is a key process in Earth history because it enabled plants to conquer land and transform the terrestrial surface. Among the vascular tissues, the phloem is particularly intriguing because of its complex functionality. In angiosperms, its principal components are the sieve elements, which transport phloem sap, and their neighboring companion cells. Together, they form a functional unit that sustains sap loading, transport, and unloading. The developmental trajectory of sieve elements is unique among plant cell types because it entails selective organelle degradation including enucleation. Meticulous analyses of primary, so-called protophloem in the Arabidopsis thaliana root meristem have revealed key steps in protophloem sieve element formation at single-cell resolution. A transcription factor cascade connects specification with differentiation and also orchestrates phloem pole patterning via noncell-autonomous action of sieve element-derived effectors. Reminiscent of vascular tissue patterning in secondary growth, these involve receptor kinase pathways, whose antagonists guide the progression of sieve element differentiation. Receptor kinase pathways may also safeguard phloem formation by maintaining the developmental plasticity of neighboring cell files. Our current understanding of protophloem development in the A. thaliana root has reached sufficient detail to instruct molecular-level investigation of phloem formation in other organs.

Formation of inter-and intraxylary phloem in some species of Argyreia Lour. (Convolvulaceae)

The development of inter-and intraxylary phloem was investigated in nineteen species of Argyreia Lour. Among all species, differentiation of intraxylary protophloem was observed concomitant to the regular external protophloem from the procambial derivatives (except A. nervosa). However, A. nervosa, showed the formation of medullary bundles along with the regular protoxylem while the development of intraxylary phloem was observed only after the establishment of a complete ring of the vascular cambium and deposition of a few secondary xylem elements. In all the species (except A. nervosa), additional intraxylary phloem differentiated from the adjacent parenchyma and the intraxylary cambium initiated at the periphery of the pith. It divided uni-directionally and showed deposition of only phloem elements. In the transverse view, sieve elements of intraxylary phloem were oval to circular, rectangular, or multi-angled or sometimes in a cluster of three to several cells with simple and compound sieve plates oriented obliquely on their terminal ends. In the thick stems of A. cuneata, A. elliptica, A. lawii, A. mastersii, A. nervosa, A. sericea, A. sharadchandrajii and A. splendens, thin-walled unlignified axial parenchyma strands embedded within the secondary xylem divide and differentiated into isolated or groups of interxylary phloem elements. In the transverse view, these sieve elements were like regular phloem (oval to circular) in appearance but occasionally they may be narrow in diameter, tangentially flattened and arranged in clusters. In thick stems, earlier-formed sieve elements of the interxylary phloem collapse and get crushed due to the expansion of adjacent cells. The remaining species though showed the presence of parenchyma strands within the secondary xylem, no interxylary phloem was observed even in thick stems. Such parenchyma cells within islands always showed the presence of druses.

Diversity of staminal nectariferous appendages in disymmetric and zygomorphic flowers of Fumarioideae (Papaveraceae).

Staminal nectaries show diversity in their position, size, shape, color, and number in Ranunculales. In Papaveraceae, nectaries only appear at the base of stamen in these lineages with disymmetric and zygomorphic flowers. However, the diversity of the staminal nectaries' developmental characteristics and structure is unknown. The diversity of staminal nectaries of Hypecoum erectum, Ichtyoselmis macrantha, Adlumia asiatica, Dactylicapnos torulosa, Corydalis edulis, and Fumaria officinalis (six species belonging to six genera, respectively) in the Fumarioideae was investigated under scanning electron microscopy, light microscopy, and transmission electron microscopy. In all species studied, according to the developmental characteristics of the nectaries, four developmental stages can be divided into initiation, enlargement, differentiation, and maturation, and the number of nectaries can be determined at the stage of initiation (stage 1), and morphological differentiation occurs at the developmental stage 3. The staminal nectaries consist of secretory epidermis, parenchyma tissue, and phloem with some sieve tube elements reaching the secretory parenchyma cells; however, the number of cell layers of parenchyma can vary from 30 to 40 in I. macrantha and D. torulosa, to only 5 to 10 like in F. officinalis. Secretory epidermis cells are larger than secretory parenchyma cells with abundant microchannels on the outer cell wall. There were abundant mitochondria, Golgi bodies, rough endoplasmic reticulum, and plastids in secretory parenchyma cells. Nectar is stored in the intercellular space and exuded to the exterior via microchannels. In A. asiatica, according to the evidence of small secretory cell characteristics such as dense cytoplasm, and numerous mitochondria, together with the filamentous secretions present on the surface of epidermal cells on groove, it can be inferred that the U-shaped sulcate which is located in the white projection formed at the filament of triplets in A. asiatica is nectariferous.