Epidermal Cell Layers Research Articles

Biochar-based fertiliser enhances nutrient uptake and transport in rice seedlings

Biochar-based compound fertilisers (BCF) are gaining increasing attention as they are cost-effectiveness and improve soil fertility and crop yield. However, little is known about the mechanisms by which micron-size BCF particles enhance crop growth. In the present study, Wuyunjing7 rice seedlings were exposed to micron-size particles of wheat straw-based BCF (mBCF) diffused through a 25-μm nylon mesh. The control was fertilised with urea, diammonium phosphate, and potassium chloride to ensure that both treatments received comparables level of N, P, and K. The effects of mBCF on rice seedling growth were evaluated by determining the changes in nitrogen uptake and utilisation via nitrogen content measurements, short-term 15N-NH4+ influx assays, and analyses of transcript-level nutrient transporter gene expression. The shoot biomass of rice seedling treated with mBCF at the rate of 5 mg/ g soil was 33% greater than that for the control. Root and shoot 15N accumulation rates were 44% and 14% higher, respectively, in the mBCF-treated than the control. The mBCF-treated rice seedlings had higher phosphorus, potassium, and iron content than the control. Moreover, the treatments significantly differed in terms of their nutrient transporter gene expression levels. Spectroscopy and microscopy were used to visualise nutrient distributions across transverse root sections. There were relatively higher iron oxide nanoparticle and silicon-based compound concentrations in the roots of the mBCF-treated rice seedlings than in those of the control. The foregoing difference might account for the fact that the growth of the mBCF-treated rice was superior to that of the control. We demonstrated that the mBCF treatment created a more negative electrical potential at the root epidermal cell layer (~ − 160 mV) than the root surface. This potential difference may have been the driving force for mineral nutrient absorption.

Proximate larval epidermal cell layer generates forces for Pupal thorax closure in Drosophila.

During tissue closures, such as embryonic dorsal closure in Drosophila melanogaster, a proximate extra-embryonic layer, amnioserosa, generates forces that drive migration of the flanking lateral embryonic epidermis, thereby zip-shutting the embryo. Arguably, this paradigm of tissue closure is also recapitulated in mammalian wound healing wherein proximate fibroblasts transform into contractile myofibroblasts, develop cell junctions, and form a tissue layer de novo: contraction of the latter then aids in wound closure. Given this parallelism between disparate exemplars, we posit a general principle of tissue closure via proximate cell layer-generated forces. Here, we have tested this hypothesis in pupal thorax closure wherein 2 halves of the presumptive adult thorax of Drosophila, the contralateral heminotal epithelia, migrate over an underlying larval epidermal cell layer. We show that the proximate larval epidermal cell layer promotes thorax closure by its active contraction, orchestrated by its elaborate actomyosin network-driven epithelial cell dynamics, cell delamination, and death-the latter being prefigured by the activation of caspases. Larval epidermal cell dynamics generate contraction forces, which when relayed to the flanking heminota-via their mutual integrin-based adhesions-mediate thorax closure. Compromising any of these contraction force-generating mechanisms in the larval epidermal cell layer slows down heminotal migration, while loss of its relay to the flanking heminota abrogates the thorax closure altogether. Mathematical modeling further reconciles the biophysical underpinning of this emergent mechanism of thorax closure. Revealing mechanism of thorax closure apart, these findings show conservation of an essential principle of a proximate cell layer-driven tissue closure.

Stem anatomical survey of the genera Matricaria and Tripleurospermum (Asteraceae) from Turkey with its taxonomical and ecological implications

A comparative anatomical study of the stems in 32 taxa assigned in the two related genera; Matricaria (4 taxa) and Tripleurospermum (28 taxa, 30 accessions), was carried out in Turkey by using cluster analysis (CA) and principal component analysis (PCA) to address generic classification and taxa delimitation. All the studied taxa have the following stem characteristics: one layer of epidermal cells with a sparse distribution of non-glandular trichomes, a cortex composed of interchanging collenchyma and chlorenchyma cells, a number of schizogenous secretory ducts near the bundles, ovate to oblong and open collateral vascular bundles which are arranged in a ring and are variable in size, and parenchymatous pith. The differences among the taxa are mainly the thickness of the xylem in the vascular bundle, the length of the epidermal cells and the pith cell size. The taxonomic and ecological values of the anatomical data are discussed in light of the current framework.

Pharmacognostical, physicochemical and phytochemical evaluation of Huberantha senjiana (Annonaceae) leaf: An endemic tree of Gingee Hills Tamil Nadu India

Context: Huberantha senjiana (Annonaceae) is a small tree found in dry rocky soils. It is an endemic species native to the Gingee hills of the Villupuram district of Tamil Nadu, India. The literature survey provides no scientific evidence on its pharmacognostical as well as pharmacological aspect. Aims: To evaluate the detailed pharmacognostical, physicochemical, and phytochemical characters of H. senjiana leaves. Methods: The pharmacognostic evaluation, such as macroscopic and microscopic characters of fresh leaf and powder, was done. Physicochemical constants like moisture content, extractive values, ash values, foaming index, swelling index, and fluorescence analysis were carried out. The phytochemical screening test and elemental analysis of the powdered leaves were also studied. Results: Microscopy of the leaf revealed a single layer of square-shaped epidermal cells, the adaxial epidermal layer is apostomatic, and the abaxial epidermal layer is stomatiferous with paracytic stomata, an arch-shaped vascular bundle, clusters of prismatic crystals, spongy parenchyma cells, and palisade cells. Prismatic calcium oxalate crystals, fibers, epidermal trichomes, palisade mesophyll, xylem vessels, and a fragment of the epidermal cell with paracytic stomata were also identified in the microscopy of powdered samples. The phytochemical analysis of sequential extracts showed the presence of alkaloids, flavonoids, cardiac glycosides, terpenoids, carbohydrates, tannins, and steroids. The elemental analysis revealed the presence of heavy metals within the standard limit and trace elements in different concentrations. Conclusions: The pharmacognostical, physicochemical, and phytochemical data have been reported for the first time, which provides referential information for the right identification and standardization of this unexplored species.

Histological studies on somatic embryogenesis in rice (Oryza sativ L.)

Rice (Oryza sativa) embryogenic calli were obtained from mature zygotic embryos culture using two varieties of rice, Sakha 101 and Sakha104 on Murashige and Skoog (1962 ) medium supplemented with 1mg/l, 2mg/l and 3mg/l 2,4- dichlorophenoxy acetic acid. The results indicated that the best medium was that containing 3mg/l. Histological analysis of somatic embryogenesis revealed that after two weeks of culture of explants on the callus induction medium, somatic embryo development began with a cluster of proembryogenic cells in the peripheral region of the calli. The outer cell layer of embryogenic calli consisted of small and isodiametric cells, each with a dense cytoplasm and a prominent nucleus and nucleolus, whereas the inner cell layer is composed of large cells with small nuclei and large vacuoles. These embryogenic cells underwent a series of organized divisions and formed the proembryo with a well-defined protodermis. At 20 days after initiation of culture, these proembryos continued a series of organized divisions and gave rise to globular somatic embryos which are delimited by a well-defined layer of epidermal cells with conspicuous nuclei. These somatic embryos had no apparent vascular connection with the mother tissue and had a suspensor. After ten days of culture on regeneration medium, globular somatic embryos developed into heart-shaped somatic embryos, which consisted of cells with prominent nuclei and dense cytoplasm. After 15 days of culture on regeneration medium torpedo-shaped somatic embryos were observed. Then, after 25 to30 days, it turned into a monocotyledon form.

Antimicrobial Late Cornified Envelope Proteins: The Psoriasis Risk Factor Deletion of LCE3B/C Genes Affects Microbiota Composition

Late cornified envelope proteins are predominantly expressed in the skin and other cornified epithelia. On the basis of sequence similarity, this 18-member homologous gene family has been subdivided into six groups. The LCE3 proteins have been the focus of dermatological research because the combined deletion of LCE3B and LCE3C genes (LCE3B/C-del) is a risk factor for psoriasis. We previously reported that LCE3B/C-del increases the expression of the LCE3A gene and that LCE3 proteins exert antibacterial activity. In this study, we analyzed the antimicrobial properties of other family members and the role of LCE3B/C-del in the modulation of microbiota composition of the skin and oral cavity. Differences in killing efficiency and specificity between the late cornified envelope proteins and their target microbes were found, and the amino acid content rather than the order of the well-conserved central domain of the LCE3A protein was found responsible for its antibacterial activity. Invivo, LCE3B/C-del correlated with a higher beta-diversity in the skin and oral microbiota. From these results, we conclude that all late cornified envelope proteins possess antimicrobial activity. Tissue-specific and genotype-dependent antimicrobial protein profiles impact skin and oral microbiota composition, which could direct toward LCE3B/C-del‒associated dysbiosis and a possible role for microbiota in the pathophysiology of psoriasis.

Bioenergy sorghum’s deep roots: A key to sustainable biomass production on annual cropland

AbstractBioenergy sorghum has high biomass yield potential, drought resilience, good nitrogen use efficiency, and a root system that contributes to the accumulation of soil organic carbon. In this study, field grown bioenergy sorghum root systems were analyzed during the growing season to characterize their depth, biomass, morphology, anatomy, and gene expression profiles. Bioenergy sorghum roots grew continuously during a 155‐day growing season producing ~175 nodal roots, accumulating ~7 Mg of dry biomass per hectare, and reaching >2 m deep in the soil profile. Nodal roots within 20 cm of the stem were 1–5 mm in diameter, whereas roots deeper in soil profiles were enriched in lateral roots with small diameters (~30–500 µm) enabling growth through soil macropores. In older field‐grown plants, roots with intact endodermal, vascular and inner root tissues were surrounded by degraded or aerenchyma‐filled epidermal and cortical cell layers. Transcriptome analysis of nodal, surface, and deep roots identified >2,500 differentially expressed genes involved in root growth, transport, adaptation, defense, and AMF–root interaction. Deep roots (180–240 cm) differentially expressed genes that regulate lateral root growth. Surface roots (0–20 cm) located mid‐row differentially expressed genes involved in nitrate transport, whereas ammonium transport genes were expressed in surface and deep roots and genes involved in phosphate transport were expressed in nodal, surface, and deep roots. Overall, bioenergy sorghum's long growing season enables root systems to grow deeper and accumulate more biomass than annual grain crops such as maize, attributes that could help restore annual cropland soil organic carbon levels and improve soil productivity. Deep roots active in nutrient transport are positioned to take‐up fertilizer leached deep into soil profiles mitigating potential nutrient run‐off. Bioenergy sorghum's large and deep root system is a key to sustainable production of biofuels, biopower, and bioproducts on annual cropland.

Clathrin light chains regulate hypocotyl elongation by affecting the polarization of the auxin transporter PIN3 in Arabidopsis.

PIN-FORMED (PIN)-dependent directional auxin transport is crucial for plant development. Although the redistribution of auxin mediated by the polarization of PIN3 plays key roles in modulating hypocotyl cell expansion, how PIN3 becomes repolarized to the proper sites within hypocotyl cells is poorly understood. We previously generated the clathrin light chain clc2-1 clc3-1 double mutant in Arabidopsis thaliana and found that it has an elongated hypocotyl phenotype compared to the wild type. Here, we performed genetic, cell biology, and pharmacological analyses combined with live-cell imaging to elucidate the molecular mechanism underlying the role of clathrin light chains in hypocotyl elongation. Our analyses indicated that the defects of the double mutant enhanced auxin maxima in epidermal cells, thus, promoting hypocotyl elongation. PIN3 relocated to the lateral sides of hypocotyl endodermal cells in clc2-1 clc3-1 mutants to redirect auxin toward the epidermal cell layers. Moreover, the loss of function of PIN3 largely suppressed the long hypocotyl phenotype of the clc2-1 clc3-1 double mutant, as did treatment with auxin transport inhibitors. Based on these data, we propose that clathrin modulates PIN3 abundance and polarity to direct auxin flux and inhibit cell elongation in the hypocotyl, providing novel insights into the regulation of hypocotyl elongation.

Single-cell transcriptomics sheds light on the identity and metabolism of developing leaf cells.

As the main photosynthetic instruments of vascular plants, leaves are crucial and complex plant organs. A strict organization of leaf mesophyll and epidermal cell layers orchestrates photosynthesis and gas exchange. In addition, water and nutrients for leaf growth are transported through the vascular tissue. To establish the single-cell transcriptomic landscape of these different leaf tissues, we performed high-throughput transcriptome sequencing of individual cells isolated from young leaves of Arabidopsis (Arabidopsis thaliana) seedlings grown in two different environmental conditions. The detection of approximately 19,000 different transcripts in over 1,800 high-quality leaf cells revealed 14 cell populations composing the young, differentiating leaf. Besides the cell populations comprising the core leaf tissues, we identified subpopulations with a distinct identity or metabolic activity. In addition, we proposed cell-type-specific markers for each of these populations. Finally, an intuitive web tool allows for browsing the presented dataset. Our data present insights on how the different cell populations constituting a developing leaf are connected via developmental, metabolic, or stress-related trajectories.

Acceleration of Aril Cracking by Ethylene in Torreya grandis During Nut Maturation.

Torreya grandis ‘Merrillii’ is a famous nut with great nutritional value and high medicinal value. Aril cracking is an important process for seed dispersal, which is also an indicator of seed maturation. However, the cracking mechanism of T. grandis aril during the maturation stage remains largely unknown. Here, we provided a comprehensive view of the physiological and molecular levels of aril cracking in T. grandis by systematically analyzing its anatomical structure, physiological parameters, and transcriptomic response during the cracking process. These results showed that the length of both epidermal and parenchymatous cell layers significantly increased from 133 to 144 days after seed protrusion (DASP), followed by a clear separation between parenchymatous cell layers and kernel, which was accompanied by a breakage between epidermal and parenchymatous cell layers. Moreover, analyses of cell wall composition showed that a significant degradation of cellular wall polysaccharides occurred during aril cracking. To examine the global gene expression changes in arils during the cracking process, the transcriptomes (96 and 141 DASP) were analyzed. KEGG pathway analysis of DEGs revealed that 4 of the top 10 enriched pathways were involved in cell wall modification and 2 pathways were related to ethylene biosynthesis and ethylene signal transduction. Furthermore, combining the analysis results of co-expression networks between different transcription factors, cell wall modification genes, and exogenous ethylene treatments suggested that the ethylene signal transcription factors (ERF11 and ERF1A) were involved in aril cracking of T. grandis by regulation of EXP and PME. Our findings provided new insights into the aril cracking trait in T. grandis.

Pharmacognostic and Preliminary Phytochemical Evaluation of Leaf of Syzygium Cumini (L.) Skeels

Syzygium cumini (L.) Skeels (Family: Myricaceae) commonly known as Jamun is a widely used medicinal plant in Ayurveda. In spite of its numerous medicinal attributes, no published work is available on pharmacognostic characterization, physicochemical analysis of its leaves. The measures taken for pharmacognostic characterization were macroscopy, microscopy, powder microscopy, physicochemical evaluation, fluorescence analysis, and preliminary phytochemical screening. The microscopic evaluation showed useful characters for the recognition of leaf of Syzygium cumini (L.) Skeels . Transverse section, showed presence of single layer of wavy epidermal cells with striated cuticle single layer Palisade beneath upper epidermis in lamina region (contains compact elongated cells), Spheraphide in lamina region, collenchyma below the upper epidermis and above the lower epidermis in midrib region, Xylem and phloem in center, Sclerenchyma in between vascular bundle and collenchyma in midrib region. Wavy epidermal cell in the upper epidermis, anisocytic stomata in the lower epidermis, Bordered pitted reticulate vessels, Calcium oxalate crystal sheath in the lamina, fragment of fibers and Spiral vessels were observed in powder microscopy. Physicochemical studies showed total ash (3.1%), acid insoluble ash (0.7%), alcohol soluble extractive values (10.96 %), and water-soluble extractive values (12.32 %). Phytochemical analysis revealed the presence of sugar, lipid, Glycoside, saponins, phenols, flavonoids, tannins, tri-terpenoids and steroids. The study forms the first report on pharmacognostic characters and a physicochemical parameter which could be useful for identification and authentication of the plant.

Mechanical role of actinotrichia in shaping the caudal fin of zebrafish

Spear-like collagen complexes, known as actinotrichia, underlie the epidermal cell layer in the tip of teleost fins and are known to contribute toward fin formation; however, their specific role remains largely unclear. In this study, we investigated of actinotrichia in the role of caudal fin formation by generating collagen9a1c (col9a1c)-knockout zebrafish. Although actinotrichia were initially produced normally and aligned correctly in the knockout fish, the number of actinotrichia decreased as the fish grew and their alignment became disordered. Simultaneously, the fin tip gradually shortened in the dorsal-ventral direction and the entire fin became oval-shaped, while the fin-rays rarely bifurcated and instead underwent fusion, suggesting that actinotrichia are essential for spreading fins dorsoventrally. Furthermore, the epithelial cells that are usually thinly spread in normal fish became spherical in the knockout fish, reducing the area covered by each cell and thus the area of the fin tip. Together, these findings suggest that the tight alignment of actinotrichia provides physical support in the dorsal-ventral direction that allows caudal fins to expand in a triangular-shape.

Effects of different calcium oxide dipping concentrations in aroma profiles of pink lady apple cultivar during cold-storage

Objective: The aim of this research was to assess the profile of volatile compounds changes during the cold storage in ‘Pink Lady’ apples. Material and Methods: Six-year-old Cripps Pink (Pink Lady) fruits of apple trees grafted onto M9 rootstock were used as a plant material for this study. The trees were in a commercial orchard in Çanakkale-Turkey. Fruits were carefully picked up by hand at the commercial harvesting time. The fruits were dipped into calcium oxide solutions (concentrations of 2 and 4%) during three minutes. Control fruits were exposed to distilled water. Fruits were stored at 0° C and 90% relative humidity for 6 months. The aroma profiles of apples determined by GC/MS (Gas Chromatography/Mass Spectrometry) analysis followed by liquid-liquid extraction. Stored fruits were analyzed for their volatile contents at the 2nd, 4th and 6th months. Results: Fresh fruits at harvest period contained 15 volatile compounds in total. However, higher levels of aroma volatile compounds were detected in 6 months of cold storage. According to the chromatography results, control fruits had 24 volatile compounds, 2% CaO treated fruits had 25 volatiles and 4% CaO treated fruits had 27 volatile compounds at the end of the 6 months of cold storage. Apples at the initial stage produced an abundance of hexyl acetate (4.56%), butyl acetate (3.83%), and hexyl hexanoate (1.68%), which confer typical apple aroma characteristics. Mostly, ester production exhibited a fairly broad peak, declining as fruit aged. Isobutyric acid, allyl ester (initial 0.55%) was lower at the beginning of the storage compare to the end of storage (control fruits 0.06%, 2%CaO 0.13%, 4% CaO 0.20%). Conclusion: CaO applications especially 4% concentration had deformation effect on epidermal layer cells on fruit surface. As a result, CaO applications had a significant effect on aroma enhancement in Pink Lady apples during cold storage.

Development and structure of four different stamens in Clematis macropetala (Ranunculaceae): particular emphasis on staminodes and staminal nectary.

The stamens of angiosperms are diverse in number, colour and structure. The morphological and structural changes of stamens show important evolutionary significance for improving pollination efficiency. In Clematis macropetala, the androecium consists of fertile stamens and tepaloid staminodes. However, studies on the developmental features, structures and possible functions of stamens are few. In this study, the stamen ontogeny, micromorphology and nectary structure of C. macropetala were studied by scanning electron microscopy, light microscopy and transmission electron microscopy. The results indicate that the stamens can be divided into four forms according to shape and anther size: tepaloid staminode (St1), spatulate staminode (St2), linear-spatulate fertile stamen (St3) and linear fertile stamen (St4). The characteristics of stamen development are similar in the early stage but gradually differentiate in the later stage. St1 has delayed development and no anther differentiation. St2 develops abnormally at the early stage of anther differentiation. St3 and St4 are fertile, but their anther sizes are different. Nine epidermal cell types were observed in stamens, with only 4 types in St1 and 6-7 types in St2, St3 and St4. Nectary tissue appears on the adaxial side of the filament base. The nectary is composed of only one layer of secretory epidermal cells, which have a large nucleus, dense cytoplasm and well-developed wall ingrowth. Nectar is released through micro-channels in the cuticle of the outer wall. In Ranunculaceae, the staminal nectary is often located on fertile or sterile stamens, and the position, structure and micromorphology of secretory tissues of the stamen within Ranunculales are discussed.

The Plant Cuticle: An Ancient Guardian Barrier Set Against Long-Standing Rivals.

The aerial surfaces of plants are covered by a protective barrier formed by the cutin polyester and waxes, collectively referred to as the cuticle. Plant cuticles prevent the loss of water, regulate transpiration, and facilitate the transport of gases and solutes. As the cuticle covers the outermost epidermal cell layer, it also acts as the first line of defense against environmental cues and biotic stresses triggered by a large array of pathogens and pests, such as fungi, bacteria, and insects. Numerous studies highlight the cuticle interface as the site of complex molecular interactions between plants and pathogens. Here, we outline the multidimensional roles of cuticle-derived components, namely, epicuticular waxes and cutin monomers, during plant interactions with pathogenic fungi. We describe how certain wax components affect various pre-penetration and infection processes of fungi with different lifestyles, and then shift our focus to the roles played by the cutin monomers that are released from the cuticle owing to the activity of fungal cutinases during the early stages of infection. We discuss how cutin monomers can activate fungal cutinases and initiate the formation of infection organs, the significant impacts of cuticle defects on the nature of plant–fungal interactions, along with the possible mechanisms raised thus far in the debate on how host plants perceive cutin monomers and/or cuticle defects to elicit defense responses.

LCM and RNA-seq analyses revealed roles of cell cycle and translational regulation and homoeolog expression bias in cotton fiber cell initiation

BackgroundCotton fibers provide a powerful model for studying cell differentiation and elongation. Each cotton fiber is a singular and elongated cell derived from epidermal-layer cells of a cotton seed. Efforts to understand this dramatic developmental shift have been impeded by the difficulty of separation between fiber and epidermal cells.ResultsHere we employed laser-capture microdissection (LCM) to separate these cell types. RNA-seq analysis revealed transitional differences between fiber and epidermal-layer cells at 0 or 2 days post anthesis. Specifically, down-regulation of putative cell cycle genes was coupled with upregulation of ribosome biosynthesis and translation-related genes, which may suggest their respective roles in fiber cell initiation. Indeed, the amount of fibers in cultured ovules was increased by cell cycle progression inhibitor, Roscovitine, and decreased by ribosome biosynthesis inhibitor, Rbin-1. Moreover, subfunctionalization of homoeologs was pervasive in fiber and epidermal cells, with expression bias towards 10% more D than A homoeologs of cell cycle related genes and 40–50% more D than A homoeologs of ribosomal protein subunit genes. Key cell cycle regulators were predicted to be epialleles in allotetraploid cotton. MYB-transcription factor genes displayed expression divergence between fibers and ovules. Notably, many phytohormone-related genes were upregulated in ovules and down-regulated in fibers, suggesting spatial-temporal effects on fiber cell development.ConclusionsFiber cell initiation is accompanied by cell cycle arrest coupled with active ribosome biosynthesis, spatial-temporal regulation of phytohormones and MYB transcription factors, and homoeolog expression bias of cell cycle and ribosome biosynthesis genes. These valuable genomic resources and molecular insights will help develop breeding and biotechnological tools to improve cotton fiber production.

Comparative ultrastructural-functional characterizations of the skin in three reptile species; Chalcides ocellatus, Uromastyx aegyptia aegyptia, and Psammophis schokari aegyptia (FORSKAL, 1775): Adaptive strategies to their habitat.

The current investigation was planned utilizing SEM, histological, and furthermore cytokeratin immunohistochemical to give a full depiction of skin of three reptiles species; Chalcides ocellatus (Scincidae), Uromastyx aegyptia aegyptia (Agamidae), and Psammophis schokari aegyptia (Colubridae) captured from Egypt with various ecological environment. Our SEM results showed different scales covered epidermis of three reptile's species with diverse surface microstructure. Overlapped rhomboid scales with numerous lenticular sense organs with numerous pores and oberhäutchen layer with microridges in C. ocellatus. In U. aegyptia, scales were overlapped elliptical-shaped possess lens-like sense structure with several scattered pits and oberhäutchen layer with polygonal outlined cells. While in P. schokari aegyptia, smooth scales flattened with two large dome-shaped scale receptors/sensilla and lens-like sense structure, moreover polygonal-shaped micro-ornamentation in scale hinge joints were observed. Histologically, skin of three species had outer epidermis with stratum germinativum, stratum corneum (α-keratin, β-keratin layer) capped by surface Oberhäutchen and inner dermis. Osteoderms were observed with dermis of C. ocellatus. There are marked variation within pigment cells types among examined species. Melanophores observed in dermal layer of C. ocellatus, while in U. aegyptia, three pigment cells in tegument dermis; melanophores, xanthophores, and iridophores whereas, P. schokari aegyptia had two forms of chromatophore cells (melanophores and iridophores) in dermis and few melanophores scattered between stratum germinativum cells. The highest cytokeratin immunostaining observed in epidermal cell layer of U. aegyptia aegyptia than two other species. Conclusion, dry scaly skin of reptiles reflects a great range of functional aspects and success to adapt with terrestrial life.

Tomato SlBL4 plays an important role in fruit pedicel organogenesis and abscission

Abscission, a cell separation process, is an important trait that influences grain and fruit yield. We previously reported that BEL1-LIKE HOMEODOMAIN 4 (SlBL4) is involved in chloroplast development and cell wall metabolism in tomato fruit. In the present study, we showed that silencing SlBL4 resulted in the enlargement and pre-abscission of the tomato (Solanum lycopersicum cv. Micro-TOM) fruit pedicel. The anatomic analysis showed the presence of more epidermal cell layers and no obvious abscission zone (AZ) in the SlBL4 RNAi lines compared with the wild-type plants. RNA-seq analysis indicated that the regulation of abscission by SlBL4 was associated with the altered abundance of genes related to key meristems, auxin transporters, signaling components, and cell wall metabolism. Furthermore, SlBL4 positively affected the auxin concentration in the abscission zone. A dual-luciferase reporter assay revealed that SlBL4 activated the transcription of the JOINTLESS, OVATE, PIN1, and LAX3 genes. We reported a novel function of SlBL4, which plays key roles in fruit pedicel organogenesis and abscission in tomatoes.

A cellular expression map of epidermal and subepidermal cell layer-enriched transcription factor genes integrated with the regulatory network in Arabidopsis shoot apical meristem.

Transcriptional control of gene expression is an exquisitely regulated process in both animals and plants. Transcription factors (TFs) and the regulatory networks that drive the expression of TF genes in epidermal and subepidermal cell layers in Arabidopsis are unexplored. Here, we identified 65 TF genes enriched in the epidermal and subepidermal cell layers of the shoot apical meristem (SAM). To determine the cell type specificity in different stages of Arabidopsis development, we made YFP based transcriptional fusion constructs by taking a 3‐kb upstream noncoding region above the translation start site. Here, we report that for ~52% (22/42) TF genes, we detected transcription activity. TF genes derived from epidermis show uniform expression in early embryo development; however, in the late globular stage, their transcription activity is suppressed in the inner cell layers. Expression patterns linked to subepidermal cell layer identity were apparent in the postembryonic development. Potential upstream regulators that could modulate the activity of epidermal and subepidermal cell layer‐enriched TF genes were identified using enhanced yeast‐one‐hybrid (eY1H) assay and validated. This study describes the activation of TF genes in epidermal and subepidermal cell layers in embryonic and postembryonic development of Arabidopsis shoot apex.

The Cytokinin Status of the Epidermis Regulates Aspects of Vegetative and Reproductive Development in Arabidopsis thaliana.

The epidermal cell layer of plants has important functions in regulating plant growth and development. We have studied the impact of an altered epidermal cytokinin metabolism on Arabidopsis shoot development. Increased epidermal cytokinin synthesis or breakdown was achieved through expression of the cytokinin synthesis gene LOG4 and the cytokinin-degrading CKX1 gene, respectively, under the control of the epidermis-specific AtML1 promoter. During vegetative growth, increased epidermal cytokinin production caused an increased size of the shoot apical meristem and promoted earlier flowering. Leaves became larger and the shoots showed an earlier juvenile-to-adult transition. An increased cytokinin breakdown had the opposite effect on these phenotypic traits indicating that epidermal cytokinin metabolism can be a factor regulating these aspects of shoot development. The phenotypic consequences of abbreviated cytokinin signaling in the epidermis achieved through expression of the ARR1-SRDX repressor were generally milder or even absent indicating that the epidermal cytokinin acts, at least in part, cell non-autonomously. Enhanced epidermal cytokinin synthesis delayed cell differentiation during leaf development leading to an increased cell proliferation and leaf growth. Genetic analysis showed that this cytokinin activity was mediated mainly by the AHK3 receptor and the transcription factor ARR1. We also demonstrate that epidermal cytokinin promotes leaf growth in a largely cell-autonomous fashion. Increased cytokinin synthesis in the outer layer of reproductive tissues and in the placenta enhanced ovule formation by the placenta and caused the formation of larger siliques. This led to a higher number of seeds in larger pods resulting in an increased seed yield per plant. Collectively, the results provide evidence that the cytokinin metabolism in the epidermis is a relevant parameter determining vegetative and reproductive plant growth and development.