Salvinia leaves. II. Morphogenesis of the floating leaf

1979 ◽  
Vol 57 (19) ◽  
pp. 1951-1959 ◽  
Author(s):  
Judith G. Croxdale
Keyword(s):  
Leaf Surface ◽  
Apical Cell ◽  
Longitudinal Direction ◽  
Abaxial Surface ◽  
Leaf Morphogenesis ◽  
Meristematic Activity ◽  
Cell Layers ◽  
Leaf Differentiation ◽  
Marginal Meristem ◽  
Floating Leaf

The floating leaves of Salvinia arise in a manner not previously described in plants. Leaf morphogenesis is the result of meristematic activity in the leaf apical cell and two abaxial meristems. These abaxial meristems originate in the dorsal sectors of the primordium and are separated from one another by a notch which runs the length of the primordial blade region. Each meristem consists of a single longitudinal file of cells which increases the width of the blade panel by strict anticlinal divisions. These anticlinal derivatives divide periclinally to establish the cell layers of the lamina. Unlike most dorsiventral leaves in which the blade is produced by a marginal meristem. Salvinia floating leaf blade panels increase radially by the action of these abaxial meristems. Thus, the leaf surface exposed to the air is morphologically the abaxial surface and that in contact with the water is the adaxial surface. Leaf differentiation and maturation are acropetal in the longitudinal direction and from the midvein to the margins in the horizontal direction.

scholarly journals Magnetic hybrid materials interact with biological matrices

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Christine Gräfe ◽  
Elena K. Müller ◽  
Lennart Gresing ◽  
Andreas Weidner ◽  
Patricia Radon ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Field Gradient ◽  
Hybrid Materials ◽  
Biomedical Application ◽  
Magnetic Field Gradient ◽  
Apical Cell ◽  
Cell Type ◽  
Cell Layers ◽  
Barrier Model

Abstract Magnetic hybrid materials are a promising group of substances. Their interaction with matrices is challenging with regard to the underlying physical and chemical mechanisms. But thinking matrices as biological membranes or even structured cell layers they become interesting with regard to potential biomedical applications. Therefore, we established in vitro blood-organ barrier models to study the interaction and processing of superparamagnetic iron oxide nanoparticles (SPIONs) with these cellular structures in the presence of a magnetic field gradient. A one-cell-type–based blood-brain barrier model was used to investigate the attachment and uptake mechanisms of differentially charged magnetic hybrid materials. Inhibition of clathrin-dependent endocytosis and F-actin depolymerization led to a dramatic reduction of cellular uptake. Furthermore, the subsequent transportation of SPIONs through the barrier and the ability to detect these particles was of interest. Negatively charged SPIONs could be detected behind the barrier as well as in a reporter cell line. These observations could be confirmed with a two-cell-type–based blood-placenta barrier model. While positively charged SPIONs heavily interact with the apical cell layer, neutrally charged SPIONs showed a retarded interaction behavior. Behind the blood-placenta barrier, negatively charged SPIONs could be clearly detected. Finally, the transfer of the in vitro blood-placenta model in a microfluidic biochip allows the integration of shear stress into the system. Even without particle accumulation in a magnetic field gradient, the negatively charged SPIONs were detectable behind the barrier. In conclusion, in vitro blood-organ barrier models allow the broad investigation of magnetic hybrid materials with regard to biocompatibility, cell interaction, and transfer through cell layers on their way to biomedical application.

Leaflet initiation is temporally and spatially separated in simple and complex tomato (Solanum lycopersicum) leaf mutants: a developmental analysis

Botany ◽  
2010 ◽  
Vol 88 (8) ◽  
pp. 710-724 ◽  
Author(s):  
Julie Kang ◽  
Neelima R. Sinha
Keyword(s):  
Histological Analysis ◽  
Wild Type ◽  
Knox Gene ◽  
Leaf Morphogenesis ◽  
Multiple Factors ◽  
Developmental Program ◽  
Meristematic Activity ◽  
Primary Leaflet ◽  
Developmental Analysis ◽  
Leaf Mutants

Formation of a compound leaf requires the involvement of multiple factors, including KNOX1 gene expression. To further characterize simple and complex tomato leaf mutants, we analyzed their morphology and development by assessing: leaf phenotypes, primary leaf morphogenesis, expression of the class I KNOX gene LeT6, and meristematic activity of the marginal blastozone. Mutants with alterations in lobing and (or) pinnation (decrease/increase) were analyzed. Primary leaflet initiation is delayed in mutants with decreased lobing. In contrast, leaflet initiation is advanced or similar to the wild type in mutants with deep lobes. Leaves with increased pinnation along the rachis require a protracted developmental program to form their final leaf morphology. Using a morphometric analysis, we show that leaf complexity can be quantified. The expression pattern of LeT6 correlates with histological analysis of meristematic activity of the marginal blastozone, suggesting that LeT6 may play a role, through some unknown mechanism, to regulate meristematic competence, not only in the marginal blastozone to regulate leaflet lobing, but along the entire length of the leaf to regulate pinnation in compound leaves.

New and noteworthy Melastomataceae from the Yanachaga-Chemillén National Park and surrounding areas in Oxapampa, Pasco, Peru

Phytotaxa ◽  
2018 ◽  
Vol 374 (3) ◽  
pp. 185 ◽  
Author(s):  
FABIÁN A. MICHELANGELI ◽  
RENATO GOLDENBERG
Keyword(s):  
National Park ◽  
Leaf Surface ◽  
Nodal Line ◽  
Abaxial Surface ◽  
North East ◽  
The North ◽  
The Andes ◽  
Abaxial Leaf Surface ◽  
Surrounding Areas ◽  
Sclerophyllous Forests

We describe six new species of Melastomataceae from the Yanachaga-Chemillén National Park and surrounding areas from the Department of Pasco, Province of Oxapampa in Central Peru. Macrocentrum andinum is the first species of the genus described from the Andes, found along creeks at 400–500 m elev. and characterized by its anysophyllous leaves, pubescent stems and four-merous flowers. Meriania rubriflora is found in forests above 2200 m elev. and it is characterized by stem nodes with stipular flaps, leaves with an acute base and four merous, deep red flowers. Miconia palcazuana is found along rivers and streams at 300–400 m on the eastern flank of the park, and it can be distinguished by its flowers with pink anthers with glands on the connective and narrowly oblanceolate to elliptic-lanceolate leaves. Miconia yanachagaensis grows in the dwarf-sclerophyllous forests at the top of ridges and grasslands over 2800 m elev. and it is characterized by its long dendritic-pedicellate trichomes on the abaxial leaf surface, the stems flattened to terete and the presence of a conspicuous annular nodal line. Triolena rojasae is found growing on rocks along the Palcazú River and its tributaries, and it is characterized by its lanceolate-crenate leaves. Triolena vasquezii grows on the northern end of the Huancabamba canyon and the North East portion of the park and can be distinguished by its pustulate leaves with purple abaxial surface and anthers with two ventral appendages. We also present the first report of the genus Wurdastom for Peru.

scholarly journals Effect of Fungicide Mobility and Application Timing on the Management of Grape Powdery Mildew

Plant Disease ◽  
2020 ◽  
Vol 104 (4) ◽  
pp. 1167-1174 ◽  
Author(s):  
Brent Warneke ◽  
Lindsey D. Thiessen ◽  
Walter F. Mahaffee
Keyword(s):  
Powdery Mildew ◽  
Leaf Surface ◽  
Quality Standards ◽  
Pinot Noir ◽  
Abaxial Surface ◽  
Phenological Stages ◽  
Application Timing ◽  
Abaxial Leaf Surface ◽  
Detached Leaves ◽  
Grape Powdery Mildew

Grape powdery mildew (GPM) fungicide programs consist of 5 to 15 applications, depending on region or market, in an attempt to achieve the high fruit quality standards demanded by the market. Understanding how fungicides redistribute and targeting redistributing fungicide to critical crop phenological stages could improve fungicide protection of grape clusters. This study evaluated fungicide redistribution in grapevines from major fungicide groups labeled for GPM control. Translaminar and xylem redistribution was examined by placing fungicide-impregnated filter disks on the adaxial or abaxial leaf surface of detached leaves for 10 min and then incubating for 48 h before inoculating the abaxial surface with conidia. Vapor redistribution used Teflon disks sprayed with fungicides and placed on the abaxial leaf surface of detached leaves 48 h before inoculation. Disease development was rated 10 days later. Translaminar movement through calyptra was tested using flowering potted vines. All fungicides tested redistributed through at least one mechanism. Fungicide timing at critical phenological stages (early, mid, and late bloom) was assessed in small plots of cultivar Pinot noir vines. The application of trifloxystrobin, quinoxyfen, or fluopyram at different bloom stages showed that applications initiated at end of bloom resulted in the lowest berry infection probabilities of 0.073, 0.097, and 0.020, respectively. The results of this study suggest that integrating two carefully timed applications of redistributing fungicides initiated at end of bloom into a fungicide program may be an effective strategy for wine grape growers in western Oregon to produce fruit with low GPM infection.

Pleopeltis pleopeltifolia (Polypodiopsida, Polypodiaceae), a poikilochlorophyllous desiccation-tolerant fern: anatomical, biochemical and physiological responses during water stress

2014 ◽  
Vol 62 (8) ◽  
pp. 647 ◽  
Author(s):  
Ana Paula Lorenzen Voytena ◽  
Bruno Degaspari Minardi ◽  
José Bonomi Barufi ◽  
Marisa Santos ◽  
Áurea Maria Randi
Keyword(s):  
Cell Walls ◽  
Sugar Content ◽  
Longitudinal Direction ◽  
Photosynthetic Parameters ◽  
Palisade Parenchyma ◽  
Abaxial Surface ◽  
Adaxial Surface ◽  
Anomocytic Stomata ◽  
Relevant Role ◽  
Notable Increase

While many ferns have been described as desiccation tolerant (DT), few studies have reported on the mechanisms they use to survive cell desiccation. Among the species belonging to the genus Pleopeltis, P. pleopeltifolia (Raddi) Alston (Polypodiopsida, Polypodiaceae) is a DT species endemic to Brazil. So as to better characterise the mechanisms of desiccation tolerance in ferns, the present study aimed to analyse frond anatomy and physiological changes associated with desiccation and rehydration of P. pleopeltifolia. Fronds are dorsiventral, with uniseriate epidermis. The epidermal cells have various shapes, tending to stretch in the longitudinal direction of the frond. Anticlinal cell walls are sinuous, and periclinal cell walls are convex. Anomocytic stomata are restricted to the abaxial surface. Trichome-type scales are found on both sides of the frond and may play a relevant role in rehydration of this plant when water is available. The mesophyll of the frond consists of palisade parenchyma, tending to a bistratified adaxial surface and spongy parenchyma on abaxial surface. The cuticle on the adaxial surface is conspicuous, ensuring better control of internal water balance. For physiological analyses, sporophytes were subjected to desiccation for 0, 5, 10 and 15 days and rehydration for 1 day. Sporophytes showed a sharp decline in water content when kept without irrigation, reaching 9.6% after 15 days, in addition to wilting and frond rolling. A significant increase in sugar content in fronds was noticeable during desiccation, which may favour a possible osmotic adjustment and vitrification. A notable increase in proline content during rehydration was observed in fronds. During the five initial days of desiccation, the chlorophyll and carotenoid contents decreased abruptly, but after 1 day of rehydration, they had partly recovered. The photosynthetic parameters analysed by fluorescence of chlorophyll a ceased completely after 15 days of desiccation but they had recovered near to pre-desiccation levels after 1 day of rehydration.

Structural Characterization of Mint (Mentha x villosa Huds) Stem and Leaf

2019 ◽  
pp. 1-6
Author(s):  
Ana Carolina Bezerra ◽  
Luana da Silva Barbosa ◽  
José Flávio Cardoso Zuza ◽  
Agda Malany Forte de Oliveira ◽  
Camila Firmino de Azevedo
Keyword(s):  
Cross Sections ◽  
Vascular Bundle ◽  
Structural Characteristics ◽  
Glandular Trichomes ◽  
Abaxial Surface ◽  
Secretory Structures ◽  
Morphological Pattern ◽  
Cell Layers ◽  
Aromatic Species

Aims: The objective of this study was to identify the structural characteristics of the shoots of Mentha x villosa Huds and also, identify the main structures responsible for the production of active principles. Methodology: The analyzes were performed with stems and leaves from adult and healthy plants, which presented a uniform morphological pattern. The materials selected for the anatomical analyzes were fixed in FAA for 24 hours and after this period conditioned in 70% alcohol. Cross-sections and paradermic sections were manually made with a cutting blade. For sections analysis, 1% sodium hypochlorite was used for discoloration and safranine 10% dye for tissue staining. Results: The leaf of Mentha x villosa Huds presents asymmetric mesophyll, formed by palisade and lacunar parenchyma, and uniseriate epidermis. The diacytic stomata are located on the abaxial surface of the leaves with different sizes, all having a substomatal chamber. On both sides of leaves, glandular trichomes were observed in great quantity. The leaf midrib is formed by a large vascular bundle, with xylem facing the adaxial surface and phloem facing the abaxial surface. The stem presents uniseriate epidermis and below it can be found one or two layers of colenchyma. The vascular bundle consists of four main xylem points, and externally to it is found the phloem, which gives the quadrangular shape to the stem. Mentha x villosa Huds has characteristics that are common to aromatic species of the Lamiaceae family, which makes its characterization and differentiation difficult, as for example, its secretory structures which do not have taxonomic importance for differentiation on this species, since they are similar in other species of the same family. Conclusion: However, Mentha x villosa has a larger number of cell layers in the lacunar parenchyma, which is an important characteristic for the differentiation of species.

scholarly journals Adaptive morphoanatomy and ecophysiology of Billbergia euphemiae, a hemiepiphyte Bromeliaceae

Rodriguésia ◽  
2019 ◽  
Vol 70 ◽  
Author(s):  
Bianca Butter Zorger ◽  
Hiulana Pereira Arrivabene ◽  
Camilla Rozindo Dias Milanez
Keyword(s):  
Water Retention ◽  
Abaxial Surface ◽  
Outer Cortex ◽  
Selective Pressures ◽  
Cortex Cell ◽  
Storage Parenchyma ◽  
Cell Layers ◽  
Length Width ◽  
Lower Height ◽  
Inner Cortex

Abstract Habitats under distinct selective pressures exert adaptative pressures that can lead individuals of the same species to present different life strategies for their survival. The aim of this study was to analyse morphoanatomical and physiological traits for identification of adaptive ecological strategies related to both terrestrial and epiphytic life phases of Billbergia euphemiae. It was verified that B. euphemiae showed lower height, as well smaller length, width and foliar area in epiphytic phase than in terrestrial phase. Concerning to foliar anatomy, the thicknesses of leaf and water-storage parenchyma were higher in terrestrial phase, as densities of stomata and scales on the abaxial surface were higher in epiphytic phase. About the contents of photosynthetic pigments, only chlorophyll a/b ratio showed differences between life phases. In both habits, plants exhibited roots with absorption hair. In epiphytic phase, roots exhibited higher velamen thickness, smaller outer cortex, higher number of inner cortex cell layers and higher number of protoxylem poles. Thus, B. euphemiae individuals in epiphytic exhibited lots of traits related to water retention, once these plants are not into the ground. Besides, the plasticity observed may contribute for survival of this group in habitats submitted to modifications (e.g., climate change and other variations caused by human interference).

Mechanisms of Resistance to Glyphosate in a Ryegrass (Lolium Multiflorum) Biotype from Chile

Weed Science ◽  
2007 ◽  
Vol 55 (5) ◽  
pp. 435-440 ◽  
Author(s):  
Paola Michitte ◽  
Rafael De Prado ◽  
Nelson Espinoza ◽  
Juan Pedro Ruiz-Santaella ◽  
Christian Gauvrit
Keyword(s):  
Leaf Surface ◽  
Lolium Multiflorum ◽  
Glyphosate Resistance ◽  
Contact Angles ◽  
Italian Ryegrass ◽  
Foliar Uptake ◽  
Mechanisms Of Resistance ◽  
Abaxial Surface ◽  
Abaxial Leaf Surface ◽  
Target Enzyme

Glyphosate behavior was examined in Italian ryegrass plants from Chile that were sensitive (S) and resistant (R) to this herbicide. In order to explain the resistance to glyphosate, contact angles, spray retention, foliar uptake, herbicide translocation, and target enzyme activity were studied. Contact angles of glyphosate solutions at a field concentration were 40° to 45° on the abaxial surface of R leaves as compared to 70° on S. Glyphosate spray retention by R plants was 35% lower than by S plants. Glyphosate uptake by the abaxial leaf surface of R plants was about 40% lower than that of S plants. In addition, in the R plants more glyphosate migrated to the tip of the treated leaves. The target enzyme in R and S plants was sensitive to the herbicide. Based on these and previous results, it is concluded that resistance in this Italian ryegrass biotype results from lower spray retention, lower foliar uptake from the abaxial leaf surface, and altered translocation pattern. The decreases in spray retention and foliar uptake constitute new mechanisms of glyphosate resistance.

Molecular genetic approaches to leaf development: Knotted and beyond

1994 ◽  
Vol 72 (5) ◽  
pp. 617-625 ◽  
Author(s):  
Laurie G. Smith ◽  
Sarah Hake
Keyword(s):  
Molecular Genetics ◽  
Shoot Apex ◽  
Leaf Development ◽  
Molecular Basis ◽  
Leaf Surface ◽  
Molecular Genetic ◽  
Leaf Morphogenesis ◽  
Promising Alternative ◽  
Recessive Mutations ◽  
Experimental Approaches

Molecular genetics provides a promising alternative to other experimental approaches for furthering our understanding of the mechanisms controlling leaf development. We investigated the molecular basis of dominant Knotted (Kn1) mutations in maize, which cause cells associated with the lateral veins of the leaf blade to acquire characteristics of sheath or auricle and sporadically form outgrowths called knots. The kn1 gene encodes a homeodomain, a DNA-binding domain shared by many transcription factors that regulate developmental processes in animals and fungi. In normal plants, the expression of kn1 is confined to the shoot apex, but in Kn1 mutants, the gene is also expressed ectopically in the veins of developing leaves, apparently causing cells to change their developmental fates. The kn1 gene may function in the shoot apex of normal plants to promote indeterminate growth. Consistent with this hypothesis, when kn1 is expressed constitutively at high levels in the leaves of transgenic tobacco, shoots are formed on the leaf surface. Thus, our results indicate that while the kn1 gene may normally have no function in leaf development, it can alter the development of maize and tobacco leaves when it is expressed in the leaf inappropriately. Genes that normally play a role in leaf development are more likely to be defined by recessive mutations that alter leaf morphogenesis and histogenesis. Key words: leaf development, molecular genetics, Knotted.

scholarly journals The structure and distribution of glandular trichomes on the stems and leaves of drug eyebright (Euphrasia stricta D. Wolff ex J. F. Lehm.)

2012 ◽  
Vol 63 (2) ◽  
pp. 13-23 ◽  
Author(s):  
Elżbieta Weryszko-Chmielewska ◽  
Anna Matysik-Woźniak ◽  
Dagmara Sadowska
Keyword(s):  
Plant Material ◽  
Leaf Surface ◽  
Glandular Trichomes ◽  
Biologically Active ◽  
Vascular Bundles ◽  
Abaxial Surface ◽  
Capitate Trichomes ◽  
Stems And Leaves ◽  
Glandular Structures ◽  
Active Substances

<i>Euphrasia stricta</i> is a medicinal plant being one of the ingredients of "Herba Euphrasiae". Many studies have been devoted to the identification of biologically active substances in the herb of eyebright, but much less research has been done on the constitution of glandular structures of this taxon. This paper relates to glandular trichomes located on the stems and leaves of <i>E. stricta</i>. The trichome structure was examined using light and scanning electron microscopy. It was shown that the stems of <i>E. stricta</i> were mainly covered by non-glandular trichomes, whereas glandular trichomes were rarely found on them. However, clusters of short capitate trichomes were found to occur in specific epidermal regions on both surfaces of the leaf blades and bracts. On the adaxial leaf surface, glandular trichomes grew only in the grooves above the vascular bundles, while on the abaxial surface in the depressions located in the expanded part of the teeth. The glandular hairs consisted of 1-2 cells of the stalk and a two-celled head. Trichomes with 3- or 4-celled heads were found sporadically. The glandular trichomes functioned non-synchronously, since they differed in head size and the colour of cell protoplasts. The presence of a light secretion was found on the surface and around the trichomes in both fresh and dry plant material.

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