Subsidiary Cells Research Articles

Dual role of BdMUTE during stomatal development in the model grass Brachypodium distachyon.

Grasses form morphologically derived, four-celled stomata, where two dumbbell-shaped guard cells (GCs) are flanked by two lateral subsidiary cells (SCs). This innovative form enables rapid opening and closing kinetics and efficient plant-atmosphere gas exchange. The mobile bHLH transcription factor MUTE is required for SC formation in grasses. Yet whether and how MUTE also regulates GC development and whether MUTE mobility is required for SC recruitment is unclear. Here, we transgenically impaired BdMUTE mobility from GC to SC precursors in the emerging model grass Brachypodium distachyon. Our data indicate that reduced BdMUTE mobility severely affected the spatiotemporal coordination of GC and SC development. Furthermore, although BdMUTE has a cell-autonomous role in GC division orientation, complete dumbbell morphogenesis of GCs required SC recruitment. Finally, leaf-level gas exchange measurements showed that dosage-dependent complementation of the four-celled grass morphology was mirrored in a gradual physiological complementation of stomatal kinetics. Together, our work revealed a dual role of grass MUTE in regulating GC division orientation and SC recruitment, which in turn is required for GC morphogenesis and the rapid kinetics of grass stomata.

Foliar epidermal micro-morphology of selected brinjal varieties: A study on leaf surface characteristics

Studies on the leaf epidermal morphological characteristics were conducted on the three varieties of brinjal (Solanum melongena L.) belonging to the family Solanaceae. The varieties used in the study were Bhavani Gold, Purple Round and Haritha. Fresh mature brinjal leaves were randomly selected from the three experimental genotypes, and the foliar epidermal features were studied by using light microscopy and SEM imaging. Measurements were taken with an ocular and stage micrometer using 10X and 40X magnifications. The photographs were taken from mounted slides. The stomatal count and each measurement represent the average of ten readings. The upper and lower epidermal surfaces of leaf were studied for stomatal features including, stomatal distribution, stomatal type, stomatal index, stomatal pore length, stomatal pore width, guard cell length, guard cell width, subsidiary cell length and width, epidermal cell type, epidermal cell length and width, trichome type, trichome length and width. Amphistomatous, anisocytic, and with more stomata on the lower epidermal surface than the upper epidermal surface were present in all leaf varieties. On the leaves, the abaxial stomatal index ranged from 68.19 mm-2 (Bhavani Gold) to 56.67 mm-2 (Purple Round) to 58.8 mm-2 (Haritha). While on the adaxial surface, it varied from 59.67 mm-2 (Bhavani Gold), 53.46 mm-2 (Purple Round) and 56.67 mm-2 (Haritha). The three varieties of this study exhibited similarities in the pattern of epidermal cell on the adaxial and abaxial surfaces and were irregular in shape. Among the three varieties epidermal cell become irregular in outline and trichomes were present on both leaf surfaces. It becomes stellate, non-glandular, glandular and 8-12 in number. The highest trichome length was obtained in Bhavani Gold (63 μm) followed by Haritha (57.5 μm) and Purple Round (43 μm) on the upper epidermis. On the lower epidermal region maximum length was obtained in Bhavani Gold (65.5 μm) followed by Haritha (53 μm) and Purple Round (44 μm).

Impact of Roadside Dust on Growth, Development andCellular Characteristics of Tomato Plants

This thesis investigates the effect of roadside dust on the growth and development of tomato plants, specifically focusing on plant height, leaf number, terminal leaf area, lateral leaf area, root fresh weight, root dry weight, shoot fresh weight, shoot dry weight, and cellular characteristics. The study examines seven treatment groups representing varying concentrations of roadside dust applied to the plants. The results reveal significant variations in the measured parameters, indicating that the treatments had a significant effect on most of the parameters, except for root dry weight. The plant height, terminal leaf area, leaf number, and lateral leaf area showed a decreasing trend with increasing dust concentration, suggesting hindrance in vertical growth and leaf development. Root fresh weight, shoot fresh weight, and shoot dry weight also exhibited a decreasing trend as the concentration of dust increased, indicating a negative impact on root and shoot biomass. The cellular characteristics, such as guard cell, subsidiary cell, and epidermal cell measurements, demonstrated a decrease in values as dust concentrations increased, indicating adverse effects on cellular growth and development. Overall, the findings indicate that roadside dust has a detrimental effect on the growth and development of tomato plants, including biomass accumulation, leaf expansion, and cellular characteristics. Mitigation strategies, such as regular leaf cleaning, proper irrigation, and air pollution control, are recommended to minimize the negative impacts of roadside dust on plant growth and ensure optimal crop production and environmental sustainability.

Lamiales epidermal dynamics: Unveiling antimicrobial resilience in a structural symphony.

This research on Lamiales epidermal anatomy not only provides in-depth understanding of their structural traits but also highlights the significance of uncovering the inherent antimicrobial resilience embedded within these plants. Such insights hold promise for advancing natural product-based approaches in medicine, potentially contributing to the development of novel antimicrobial agents inspired by Lamiales unique biological defense mechanisms. Scanning microscopic tools were utilized to conduct foliar epidermal anatomy of nine species that belong to seven genera and four families within the Lamiales order, Plantaginaceae, Scrophulariaceae, Verbenaceae, and Lamiaceae. This approach aimed to gather both qualitative and quantitative data, facilitating the assessment of taxonomic microanatomical significance. The shape of epidermal cells and their anticlinal walls; number of epidermal cells, stomata, and trichomes; type of stomata and trichomes; length and width of epidermal cells, trichomes, stomatal pore, guard cells, and subsidiary cells; and stomatal index were determined statistically. Most of the species examined were amphistomatous and showed extensive array of trichomes diversity. The exploration of Lamiales epidermal micromorphology and their antimicrobial potential were significant for their implications in multidisciplinary fields. The pharmacological research to utilize sustainable agricultural practices prompts avenues to strengths of Lamiales order for the development of novel antimicrobial solutions and ecological benefits. RESEARCH HIGHLIGHTS: Diverse trichome morphometry reveals a wide array of trichome structures across Lamiales species. Epidermal microscopic architecture variability of epidermal cell shapes and sizes signifies the interspecies variability. Secondary metabolite localization within microanatomical structures elucidates potential hotspots for antimicrobial compound production.

Stomatal dynamics in Alloteropsis semialata arise from the evolving interplay between photosynthetic physiology, stomatal size and biochemistry.

C4 plants are expected to have faster stomatal movements than C3 species because they tend to have smaller guard cells. However, little is known about how the evolution of C4 photosynthesis influences stomatal dynamics in relation to guard cell size and environmental factors. We studied photosynthetically diverse populations of the grass Alloteropsis semialata, showing that the origin of C4 photosynthesis in this species was associated with a shortening of stomatal guard and subsidiary cells. However, for a given cell size, C4 and C3-C4 intermediate individuals had similar or slower light-induced stomatal opening speeds than C3 individuals. Conversely, when exposed to decreasing light, stomata in C4 plants closed as fast as those in non-C4 plants. Polyploid formation in some C4 plants led to larger stomatal cells and was associated with slower stomatal opening. Conversely, diversification of C4 diploid plants into wetter environments was associated with an acceleration of stomatal opening. Overall, there was significant relationship between light-saturated photosynthesis and stomatal opening speed in the C4 plants, implying that photosynthetic energy production was limiting for stomatal opening. Stomatal dynamics in this wild grass therefore arise from the evolving interplay between photosynthetic physiology and the size and biochemical function of stomatal complexes.

Morpho-anatomical studies of family lamiaceae species of district Lahore, Punjab: a revision to flora of Pakistan

BackgroundThis study was aimed to determine the taxonomic position and delimitation of fifteen Lamiaceae taxa using leaf epidermal morpho-anatomical features in Lahore. A main objective of the study was also the revision and upgradation of Lamiaceae taxa in the flora of Pakistan, as no details of studied species are found in the flora of Pakistan.MethodsThe examination of significant anatomical parameters, such as epidermal cell shape and size, stomatal types, guard and subsidiary cells shape and size, stomatal cavity size, trichome size and shape, oil droplets, crystals, and secretory cavity characteristics were studied using light microscopic (LM) and scanning electron microscopic (SEM) techniques. Among all the studied Lamiaceae species, these anatomical features varied significantly. Principal component analysis and correlation were done to distinguish the species’ similarities.ResultsMost species had pentagonal and hexagonal epidermal cells with straight anticlinal wall thickness. On the adaxial surface, paracytic stomata were found in Ocimum basilicum L. and Rosmarinus officinalis L. Diacytic stomata was observed in Ajuga reptans L. and anisocytic stomata in Galeopsis tetrahit L. In the abaxial surface, trichomes were present in five species, i.e., Mentha suaveolens Ehrh. A. reptans, Thymus vulgaris L., M. haplocalyx, and Salvia splendens Ewat. In S. splendens, peltate and glandular trichomes were seen whereas, in other species, trichomes were long, unbranched glandular and had tapering ends. In adaxial side trichomes were present only in M. suaveolens, A. reptans, S. bazyntina, O. basciculum, S. splendens, S. officinalis, S. rosemarinus. In other species, trichomes were absent on the adaxial surface. In abaxial view, M. suaveolens had the largest length of trichomes, and O. basciculum had the smallest. S. splendens L. had the largest trichome width, while T. vulgaris had the smallest.ConclusionHence, according to these findings, morpho-anatomical traits are useful for identifying Lamiaceae taxa. Also, there is a need of upgradation and addition of studied taxa in flora of Pakistan comprehensively.

Epidermal Studies in the Genus <i>Selaginella</i> Beauv.

Epidermal studies of thirty seven Indian species of Selaginella have been carried out. On the basis of the presence or absence of sclerotic fibres on the margin of the leaves, distribution of stomata and presence or absence of a ring of subsidiary cells around the stoma etc., a tentative key for the identification of these heterophyllous Indian species of Selaginella has been devised.

Multifaceted role and regulation of aquaporins for efficient stomatal movements.

Stomata are micropores on the leaf epidermis that allow carbon dioxide (CO2) uptake for photosynthesis at the expense of water loss through transpiration. Stomata coordinate the plant gas exchange of carbon and water with the atmosphere through their opening and closing dynamics. In the context of global climate change, it is essential to better understand the mechanism of stomatal movements under different environmental stimuli. Aquaporins (AQPs) are considered important regulators of stomatal movements by contributing to membrane diffusion of water, CO2and hydrogen peroxide. This review compiles the most recent findings and discusses future directions to update our knowledge of the role of AQPs in stomatal movements. After highlighting the role of subsidiary cells (SCs), which contribute to the high water use efficiency of grass stomata, we explore the expression of AQP genes in guard cellsand SCs. We then focus on the cellular regulation of AQP activity at the protein level in stomata. After introducing their post-translational modifications, we detail their trafficking as well as their physical interaction with various partners that regulate AQP subcellular dynamics towards and within specific regions of the cell membranes, such as microdomains and membrane contact sites.

CO2 response screen in grass Brachypodium reveals the key role of a MAP kinase in CO2-triggered stomatal closure.

Plants respond to increased CO2 concentrations through stomatal closure, which can contribute to increased water use efficiency. Grasses display faster stomatal responses than eudicots due to dumbbell-shaped guard cells flanked by subsidiary cells working in opposition. However, forward genetic screening for stomatal CO2 signal transduction mutants in grasses has yet to be reported. The grass model Brachypodium distachyon is closely related to agronomically important cereal crops, sharing largely collinear genomes. To gain insights into CO2 control mechanisms of stomatal movements in grasses, we developed an unbiased forward genetic screen with an EMS-mutagenized B. distachyon M5 generation population using infrared imaging to identify plants with altered leaf temperatures at elevated CO2. Among isolated mutants, a "chill1" mutant exhibited cooler leaf temperatures than wild-type Bd21-3 parent control plants after exposure to increased CO2. chill1 plants showed strongly impaired high CO2-induced stomatal closure despite retaining a robust abscisic acid-induced stomatal closing response. Through bulked segregant whole-genome sequencing analyses followed by analyses of further backcrossed F4 generation plants and generation and characterization of sodium azide and CRISPR-cas9 mutants, chill1 was mapped to a protein kinase, Mitogen-Activated Protein Kinase 5 (BdMPK5). The chill1 mutation impaired BdMPK5 protein-mediated CO2/HCO3- sensing together with the High Temperature 1 (HT1) Raf-like kinase in vitro. Furthermore, AlphaFold2-directed structural modeling predicted that the identified BdMPK5-D90N chill1 mutant residue is located at the interface of BdMPK5 with the BdHT1 Raf-like kinase. BdMPK5 is a key signaling component that mediates CO2-induced stomatal movements and is proposed to function as a component of the primary CO2 sensor in grasses.

LEAF ANATOMICAL ADAPTATIONS OF FOURTEEN TREE SPECIES GROWING IN LAGOS STATE UNIVERSITY, OJO CAMPUS. LAGOS, NIGERIA

Plants growing in different locations exhibit various anatomical adaptations which make them survive in their various habitats. Therefore, this study examined the leaf anatomical adaptations of fourteen tree species namely Acacia auriculiformis, Albizia lebbeck, Anacardium occidentale, Azadirachta indica, Carica papaya, Delonix regia, Gmelina arborea, Lagestroemia speciosa, Mangifera indica, Polyalthia longifolia, Tectona grandis, Terminalia catappa, Terminalia ivoriensis and Yucca gigantea growing in Lagos State University, Ojo Campus.. The leaf epidermal layers were isolated using nail polish; and were observed under the light microscope to determine the stomata features, epidermal cell and trichome types. The results showed that all the species were hypostomatic, with the exception of Acacia auriculiformis and Terminalia ivorensis that were amphistomatic. Eight stomatal complex types such as anomotetracytic, staurocytic, anisosytic, brachyparacytic, paracytic, pericytic, brachyparatetracytic and anomocytic were observed among the species. The stomatal density ranged from 46.05 mm-2 342.11 mm-2 on both leaf surfaces. The stomatal index ranged from 16.17% - 91.23% on both leaf surfaces. Trichomes were found in Albizia lebbeck, Delonix regia, Gmelina arborea, Polyalthia longifolia, Tectona grandis and Terminali aivorensis. The anticlinal cell wall patterns observed were round, curved, wavy and straight; while the epidermal cell shapes were irregular, isodiametric and polygonal. This study revealed that leaf anatomical adaptations such as amphistomatic leaf type, presence of stomatal complex types (anomocytic, anomotetracytic, brachyparatetracytic, staurocytic and anisocytic) with many subsidiary cells; high stomatal density and index; absence of trichomes; and wavy anticlinal cell wall pattern might be responsible for survival of the species in their locations.

Foliar epidermal micromorphology of genus Glochidion J.R.Forst. & G.Forst. (Phyllanthaceae) by using light and electron microscopy

The present study was conducted to compare both qualitative and quantitative characteristics of foliar epidermal micromorphology on some members of Glochidion in Assam. As taxonomic attributes, the foliar epidermal micromorphology study of nine taxa of both abaxial and adaxial surfaces was performed by using light microscopy (LM) and field emission scanning electron microscopy (FESEM). The result showed both amphistomatic and hypostomatic types of leaf surfaces. On the same surface of the leaf, multiple types of stomata were observed such as anomocytic, anisocytic, hemiparacytic, and paracytic types. Significant diversity and variations were observed in stomatal number, size, area, epidermal cell number, subsidiary cells, and trichomes. The stomatal index, stomatal shape, epidermal cell shape, length and width of the stomata, and trichomes showed variation among the studied taxa. Glands were absent in all studied members. Papillae and epicuticular wax crystals were observed in some taxa. In addition, a taxonomic key was also provided based on foliar leaf epidermal characteristics using qualitative and quantitative data from LM and FESEM. Based on quantitative data of foliar leaf micromorphology, principal component analysis (PCA) and cluster analysis were carried out to authenticate the micromorphological data. These would aid in the identification of taxa as well as in taxonomic delimitation.

Guard cell and subsidiary cell sizes are key determinants for stomatal kinetics and drought adaptation in cereal crops.

Climate change-induced drought is a major threat to agriculture. C4 crops have a higher water use efficiency (WUE) and better adaptability to drought than C3 crops due to their smaller stomatal morphology and faster response. However, our understanding of stomatal behaviours in both C3 and C4 Poaceae crops is limited by knowledge gaps in physical traits of guard cell (GC) and subsidiary cell (SC). We employed infrared gas exchange analysis and a stomatal assay to explore the relationship between GC/SC sizes and stomatal kinetics across diverse drought conditions in two C3 (wheat and barley) and three C4 (maize, sorghum and foxtail millet) upland Poaceae crops. Through statistical analyses, we proposed a GCSC-τ model to demonstrate how morphological differences affect stomatal kinetics in C4 Poaceae crops. Our findings reveal that morphological variations specifically correlate with stomatal kinetics in C4 Poaceae crops, but not in C3 ones. Subsequent modelling and experimental validation provide further evidence that GC/SC sizes significantly impact stomatal kinetics, which affects stomatal responses to different drought conditions and thereby WUE in C4 Poaceae crops. These findings emphasize the crucial advantage of GC/SC morphological characteristics and stomatal kinetics for the drought adaptability of C4 Poaceae crops, highlighting their potential as future climate-resilient crops.

Anatomy of leaf blade, leaf sheath and pseudopetiole in Neotropical Bambusoideae (Poaceae): Insights into structure and taxonomic contributions

Anatomical investigations aiming to seek alternative characters for the taxonomy of bamboos are almost exclusively restricted to the leaf blade. Little is known about the anatomical structure of other parts of the leaf, such as the leaf sheath and pseudopetiole. The present paper analyzed the complete structure of foliage leaves, including the foliage leaf blade, foliage leaf sheath, and pseudopetiole of species belonging to the tribes Bambuseae (subtribes Guaduinae, Chusqueinae and Arthrostylidiinae) and Olyreae (subtribe Parianinae) to identify useful characters in the taxonomy of bamboos. We used scanning electron microscopy and light microscopy to describe micromorphological and anatomical features. All species sampled share the following features: foliage leaf blades with uniseriate epidermis; adaxial bulliform cells; mesophyll with arm cells, cavities, and collateral vascular bundles. Intercostal sclerenchyma associated to bulliform cells was observed only in Arthrostylidiinae. Micromorphologically, the shape and distribution of silica bodies, presence, type, and distribution of papillae on the long cells and subsidiary cells, and the presence and distribution of trichomes may be taxonomically informative in different taxonomic levels. We highlight the absence of papillae on the surfaces of foliage leaf blade of Guaduinae since the presence of papillae is considered a putative diagnosis feature supporting the sister relationship of this subtribe with Arthrostylidiinae. We describe the anatomical structure of foliage leaf sheath for the first time for Guaduinae, Chusqueinae and Parianinae. In Guaduinae, we found a unique distribution pattern of silica cells on the abaxial surface of the leaf sheath. Anatomical data about the pseudopetiole structure also were described for the first time in bamboos species; the arrangement of vascular bundles may be taxonomically informative, especially in Guaduinae.

Surrounded by luxury: The necessities of subsidiary cells.

The evolution of stomata marks one of the key advances that enabled plants to colonise dry land while allowing gas exchange for photosynthesis. In large measure, stomata retain a common design across species that incorporates paired guard cells with little variation in structure. By contrast, the cells of the stomatal complex immediately surrounding the guard cells vary widely in shape, sizeand count. Their origins in development are similarly diverse. Thus, the surrounding cells are likely a luxury that the necessity of stomatal control cannot do without (with apologies to Oscar Wilde). Surrounding cells are thought to support stomatal movements as solute reservoirs and to shape stomatal kinetics through backpressure on the guard cells. Their variety may also reflect a substantial diversity in function. Certainly modelling, kinetic analysis and the few electrophysiological studies to date give hints of much more complex contributions in stomatal physiology. Even so, our knowledge of the cells surrounding the guard cells in the stomatal complex is far from complete.

Opuntioideae cactus stem Bioimaging analysis: Bridging taxonomy and antimicrobial research.

This study presents a comprehensive scanning electron microscopy (SEM) analysis of Opuntioideae cactus stems indigenous to the arid regions of Saudi Arabia, elucidating their intricate microstructural features. The findings not only advance taxonomic understanding by aiding in species differentiation but also reveal the antimicrobial potential of these cacti, highlighting their significance as valuable natural resources for both ecological and pharmaceutical applications. The present study is aimed to present the stem epidermal anatomical description of Opuntioideae (Cactaceae) belonging to genus Opuntia (five Species), Cylindropuntia (two Species), and Austrocylindropuntia (one Species) as tool for systematic identification. Stem epidermal anatomical features represent here are epidermal cells, stomatal complex, subsidiary cells, and trichomes findings was observed using light microscope and SEM. The stem epidermal sections were made by heating in test tube containing lactic acid and nitric acid protocol. In anatomical findings, irregular, zigzag, wavy, and polygonal epidermal cells with sinuate, sinuous, and straight anticlinal walls were observed. Quantitatively minimum length (28.05 ± 2.05 μm) and width (23.15 ± 3.41 μm) of epidermal cells were noted in Cylindropuntia kleiniae. Paracytic type of stomata present was observed in all species with kidney-shaped guard cell present in six species, and in Opuntia macrocentra and Austrocylindropuntia subulata, dumbbell-shaped guard cells were observed. The largest length of stomata (53.25 ± 2.05 μm) and width of stomata (35.10 ± 5.19 μm) were observed in Opuntia monacantha. In present research work, stem anatomical features show many diverse characters are of special attention for plant taxonomist for the correct identification and provide baseline for further study in subfamily Opuntiodeae. RESEARCH HIGHLIGHTS: The intricate microstructures of Opuntioideae cactus stems. Investigating the antimicrobial potential of compounds found within Opuntioideae cactus stems. Correlations between the unique structural features observed through SEM and the antimicrobial activity of Opuntioideae cactus stem extracts.

Mechanical advantage of subsidiary cells depends on the stomatal complex structure

Structural features of stomatal complexes influencing the mechanical advantage of subsidiary cells were studied. Light, scanning and transmission electron microscopy were used to research the morphology of Fagraea ceilanica stomatal complexes. Their guard cells are located on subsidiary cells. The walls of the subsidiary cells are thickened unevenly. The inner tangential walls are thin and most extensive as compared to other walls of these cells. The data obtained allowed a 3D model of F. ceilanica stomatal complex to be constructed. To elucidate the interaction between the guard and subsidiary cells during stomatal movements, we have applied modelling using the finite-element method. According to the modelling results, the mechanical advantage of the subsidiary cells depends on mutual location of the guard and subsidiary cells, uneven thickening, area and rigidity of the subsidiary cell walls and presence of substomatal chambers, into which the inner tangential walls of the subsidiary cells can bulge when turgor pressure in these cells increases. The modelling results were confirmed by the observed deformations in actual stomatal complex cells of F. ceilanica. The decrease in mechanical advantage of the subsidiary cells ensures stoma opening in the conditions of excessive saturation of the epidermis with water, for example, in the conditions of tropical rainforests.

Stomatal variations and their position relative to leaf epidermal cells in ten Maple species

Abstract In the present study, we investigated the structure of stomata in seven native species of Hyrcanian forests (Acer hyrcanum, A. velutinum Boiss., A. campestre, A. platanoides L., A. cappadocicum, A. monspessulanum, A. amazandaranicum), as well as non-native species that have fully adapted (A. negundo, A. negundo variegatum, and A. palmatum). We used light and electron microscopy to determine the form and position of the stomata in relation to the leaf epidermal cells. The length, width, shape, area, perimeter, and stomatal density were all measured. Our findings revealed that the stomata type of A. negundo varengiayum, A. campestre, A. hyrcanum, A. mazandaranicum and A. monsspesulanum is anomocytic, A. platanoides and A. cappadocicum have anomocytic stomata with wavy subsidiary cells, while A. palmatum has anisocytic stomata and A. velutinum has parasitic stomata. A. negundo has actinocytic stomata. Regarding the location of stomata relative to adjacent epidermal cells, we identified three types. In the first type, the stomata were flush with adjacent epidermal cells (A. cappadocicum, A. negundo, A. platanoides). In the second type, the stomata were higher (A. negundo variegatum), and in the third type, the stomata were lower (A. velutinum, A. monspesulanom, A. campestre, A. mazandaranicum, A. hyrcanum). The principal component analysis was used to determine the essential stomatal traits in differentiating between species. We also investigated the distribution of trees in the coordinate axis space based on two main components and performed cluster analysis based on stomatal characteristics. A. platanoides, A. negundo, A. negundo variegatum were in one cluster, while the other species were in separate clusters. The calculation of dissimilarity among the studied species revealed the lowest similarity between A. negundo and A. hyrcanum and the highest similarity between A. campestre and A. mazandaranicum. The results of the discriminant analysis identified stomatal density as the essential factor in differentiation between the studied species.

Taxonomic Evaluation of Spinacia oleracea L. Accessions by Morphological and Anatomical Markers

Spinacia oleracea L. is an edible crop and considered as super food due to high nutrient values. Due to these properties the pot-based project was designed to explore the most diverse accession of this species, 31 local S. oleracea accessions were evaluated taxonomically on the basis of morphological and anatomical markers. Seeds were sown in clay pots to evaluate different morphological characters. The germination period varied from 6 to 15 days while variation in number of leaves was observed to be from 12 to 68 leaves per plant. Moreover, abaxial and adaxial epidermal leaf analysis was examined under light microscope to study the existing anatomical variations. Substantial variations were observed among quantitative characters including number of subsidiary cells (3-5 on both abaxial and adaxial sides), stomata number per unit area (6-21 on abaxial side; 8-18 on adaxial side) and stomatal index (13.9-28.6 on abaxial side; 14.8-25.5 on adaxial side). The shape of epidermal cells varied from tetragonal to pentagonal, hexagonal and irregular. The results concluded that leaf epidermal anatomical markers could be applied considerably in delimiting the species to solve the existing taxonomic problems among them. However, for more authentic results it would be preferred to use more taxonomic tools in integration with anatomy to study intraspecific variations.

Cell wall anisotropy plays a key role in Zea mays stomatal complex movement: the possible role of the cell wall matrix

The opening of the stomatal pore in Zea mays is accomplished by the lateral displacement of the central canals of the dumbbell-shaped guard cells (GCs) towards their adjacent deflating subsidiary cells that retreat locally. During this process, the central canals swell, and their cell wall thickenings become thinner. The mechanical forces driving the outward displacement of the central canal are applied by the asymmetrically swollen bulbous ends of the GCs via the rigid terminal cell wall thickenings of the central canal and the polar ventral cell wall (VW) ends. During stomatal pore closure, the shrinking bulbous GC ends no longer exert the mechanical forces on the central canals, allowing them to be pushed back inwards, towards their initial position, by the now swelling subsidiary cells. During this process, the cell walls of the central canal thicken. Examination of immunolabeled specimens revealed that important cell wall matrix materials are differentially distributed across the walls of Z. mays stomatal complexes. The cell walls of the bulbous ends and of the central canal of the GCs, as well as the cell walls of the subsidiary cells were shown to be rich in methylesterified homogalacturonans (HGs) and hemicelluloses. Demethylesterified HGs were, in turn, mainly located at the terminal cell wall thickenings of the central canal, at the polar ends of the VW, at the lateral walls of the GCs and at the periclinal cell walls of the central canal. During stomatal function, a spatiotemporal change on the distribution of some of the cell wall matrix materials is observed. The participation of the above cell wall matrix polysaccharides in the well-orchestrated response of the cell wall during the reversible movements of the stomatal complexes is discussed.

The Human Brain Nucleus Incertus: A New Target in Dementia?

AbstractBackgroundThe brainstem nucleus incertus (NI) or ‘uncertain nucleus’, was originally described by Streeter in 1903 as a midline region in the floor of the fourth ventricle of the human brain with an ‘unknown’ function. A century later, the NI has been shown to play a key role in memory formation in rodents, through direct and indirect inhibition of the hippocampus; and the anatomy of the NI and its projections throughout the brain have been systematically mapped in rats, mice, and primates, but not in humans. In these novel studies, we mapped the human NI using the neuropeptide, relaxin‐3 (RLN3), as neurochemical marker. In rodents, RLN3 is produced mostly in NI neurons with some subsidiary positive cells in the periaqueductal gray and an area dorsal to the substantia nigra.MethodsSerial, free‐floating coronal sections of formalin‐fixed postmortem tissue were prepared from the pons of an adult female (aged 96 years) without a history of dementia or other neurological disorders, provided by the Banner Brain and Body Donation Program, Sun City, Arizona, USA. Using immunohistochemistry, we first identified the NI by mapping the distribution of microtubule‐associated protein‐2 (MAP2) and RLN3. The specificity of the RLN3 antibody used was verified in a dot‐blot using native RLN3 peptide. We also investigated the presence of markers detected in the NI of rats ‐ glutamic acid dehydrogenase‐65/67 (GAD65/67) and corticotropin‐releasing factor type 1 receptor (CRF1); and used a phosphorylated‐tau (AT8) to determine if the NI displayed tau accumulation.ResultsDetection of MAP2‐immunoreactivity revealed the neuronal distribution throughout the pons. RLN3‐immunoreactivity was detected in neurons in the dorsal, anterior‐medial region, revealing the broad anatomy of the human NI. Neurons within this same area were also positive for GAD65/67‐ and CRF1‐immunoreactivity, in line with previous studies; and AT8‐immunoreactivity was also detected.ConclusionsRLN3 is present in neurons of the human NI and aspects of its anatomy are shared across species, including the macaque. Accumulation of phosphorylated‐tau in the NI suggests its possible involvement in the pathology of Alzheimer’s disease and related dementias. Further comparative studies are required to better understand the neurochemical anatomy of the human NI.