An analysis of the effects of gibberellic acid on the leaflet structure of dwarf cultivars of pea (Pisum sativum)

1979 ◽  
Vol 57 (10) ◽  
pp. 1089-1092 ◽  
Author(s):  
G. F. Israelstam ◽  
Erica Davis
Keyword(s):  
Pisum Sativum ◽  
Gibberellic Acid ◽  
Surface Area ◽  
Epidermal Cells ◽  
Mesophyll Cells ◽  
Spongy Mesophyll ◽  
Number Of Layers ◽  
Dwarf Cultivar ◽  
Palisade Cells ◽  
Degree Of Differentiation

The effects of gibberellic acid (GA3) on the penultimate leaflets of dwarf and normal cultivars of pea were investigated. In control plants, the leaflets of the dwarf were heavier, thicker, and had a smaller surface area than the normal. Epidermal and palisade cells of the dwarf were longer than those of the normal cultivar and the dwarf had longer spongy mesophyll cells and more layers of spongy mesophyll than the normal, with fewer intercellular spaces.Application of GA3 to dwarf plants increased leaflet surface area and length of epidermal cells, while leaflet weight and thickness and the number of layers of spongy mesophyll cells decreased. No significant changes in the leaflet of the normal cultivar were induced by GA3.The overall effect of GA3 application to the dwarf cultivar was to induce a degree of differentiation in the penultimate leaflets such that they tended to resemble more closely those of the normal cultivar.

Acid rain effects on foliar histology of Artemisia tilesii

1984 ◽  
Vol 62 (3) ◽  
pp. 463-474 ◽  
Author(s):  
C. M. Adams ◽  
N. G. Dengler ◽  
T. C. Hutchinson
Keyword(s):  
Acid Rain ◽  
Fungal Pathogens ◽  
Leaf Tissue ◽  
Epidermal Cells ◽  
Simulated Acid Rain ◽  
Scanning Electron Micrographs ◽  
Mesophyll Cells ◽  
Spongy Mesophyll ◽  
Abnormal Cell ◽  
Naturally Occurring

The present study describes the effects of simulated acid rain (pH 2.5–5.6) on foliar histology of an arctic herb, Artemisia tilesii Ledeb., which is remarkably tolerant to naturally occurring atmospheric acidity at Smoking Hills, N.W.T. Plants were exposed to simulated acid rain twice weekly for 4 weeks in exposure chambers in the greenhouse. Droplets as acidic as pH 2.5 caused limited macroscopic foliar damage. However, much greater damage was observed when sectioned leaf tissue was examined microscopically. On leaves having no injury visible to the unaided eye, small lesions consisting of one to three collapsed epidermal cells were observed in scanning electron micrographs and in cleared leaves after exposure to rain of pH 3.0 and 3.5. Stomata remained open in damaged areas of acid-sprayed leaves. Lesions most commonly developed from an initial collapse of a few adaxial epidermal cells, followed by progressive injury of underlying tissues. Palisade and spongy mesophyll cells underwent hypertrophic (abnormal cell enlargement) and hyperplastic (abnormal cell division) responses in the region adjacent to severely collapsed tissue, causing reduced intercellular spaces. These effects isolated the injured areas from adjacent healthy tissues, and resembled wound periderm responses to fungal pathogens and to mechanical irritation. This response may be one mechanism of limiting acid rain damage.

Histopathological and ultrastructural comparison of Stemphylium sarcinaeforme and S. botryosum on red clover foliage

1978 ◽  
Vol 56 (17) ◽  
pp. 2097-2108 ◽  
Author(s):  
Verna J. Higgins ◽  
G. L. Lazarovits
Keyword(s):  
Cell Walls ◽  
Light And Electron Microscopy ◽  
Red Clover ◽  
Epidermal Cells ◽  
Blue Staining ◽  
Mesophyll Cells ◽  
Toluidine Blue Staining ◽  
Different Types ◽  
Wall Appositions ◽  
Palisade Cells

As part of a continuing study of non-host resistance, red clover leaves inoculated with the clover pathogen Stemphylium sarcinaeforme, or the closely related alfalfa pathogen S. botryosum, were examined by light and electron microscopy to compare the events occurring in the initial stages of infection. Stemphylium botryosum penetrated leaves primarily via the stomata with resultant death of the guard cells and with varying effects on adjacent epidermal cells. Appressoria were frequently formed, and although they rarely resulted in successful penetrations, the contacted epidermal cells were often markedly affected as judged by toluidine blue staining. Growth of hyphae was intercellular but very limited in its extent. At some infection sites, one to several mesophyll cells underwent extensive plasmolysis and cytoplasmic disruption. Less severely affected mesophyll cells contained large lipid bodies, abundant rough endoplasmic reticulum, and Golgi vesicles and had wall appositions at points of contact with necrotic cells or with hyphae. Stemphylium sarcinaeforme generally penetrated between or directly through the epidermal cells, causing death of the contacted cells. Hyphae grew intercellularly or intracellularly in the palisade tissue and hyphal elongation was considerably more rapid than that of S. botryosum. Palisade cells adjacent to, or containing, the hyphae underwent several different types of cytoplasmic deterioration. Mesophyll cells surrounding these areas showed the same features as comparable cells in tissue infected by S. botryosum. In tissue infected by either fungus, the exterior of host cell walls was coated with a layer of extracellular material.

scholarly journals Maximum CO 2 diffusion inside leaves is limited by the scaling of cell size and genome size

2021 ◽  
Vol 288 (1945) ◽  
pp. 20203145
Author(s):  
Guillaume Théroux-Rancourt ◽  
Adam B. Roddy ◽  
J. Mason Earles ◽  
Matthew E. Gilbert ◽  
Maciej A. Zwieniecki ◽  
...  
Keyword(s):  
Genome Size ◽  
Surface Area ◽  
Three Dimensional ◽  
Mesophyll Cells ◽  
Spongy Mesophyll ◽  
Phase Diffusion ◽  
Leaf Mesophyll ◽  
Leaf Tissues ◽  
Mesophyll Surface Area ◽  
Leaf Volume

Maintaining high rates of photosynthesis in leaves requires efficient movement of CO 2 from the atmosphere to the mesophyll cells inside the leaf where CO 2 is converted into sugar. CO 2 diffusion inside the leaf depends directly on the structure of the mesophyll cells and their surrounding airspace, which have been difficult to characterize because of their inherently three-dimensional organization. Yet faster CO 2 diffusion inside the leaf was probably critical in elevating rates of photosynthesis that occurred among angiosperm lineages. Here we characterize the three-dimensional surface area of the leaf mesophyll across vascular plants. We show that genome size determines the sizes and packing densities of cells in all leaf tissues and that smaller cells enable more mesophyll surface area to be packed into the leaf volume, facilitating higher CO 2 diffusion. Measurements and modelling revealed that the spongy mesophyll layer better facilitates gaseous phase diffusion while the palisade mesophyll layer better facilitates liquid-phase diffusion. Our results demonstrate that genome downsizing among the angiosperms was critical to restructuring the entire pathway of CO 2 diffusion into and through the leaf, maintaining high rates of CO 2 supply to the leaf mesophyll despite declining atmospheric CO 2 levels during the Cretaceous.

scholarly journals Ultrastructural and Surface Features of Apple Leaves following White Apple Leafhopper Feeding

HortScience ◽  
1996 ◽  
Vol 31 (2) ◽  
pp. 249-251
Author(s):  
Robert M. Welker ◽  
Richard P. Marini ◽  
Douglas G. Pfeiffer
Keyword(s):  
Cell Injury ◽  
Stomatal Density ◽  
Starch Granules ◽  
Feeding Damage ◽  
Abaxial Epidermis ◽  
Mesophyll Cells ◽  
Spongy Mesophyll ◽  
Transmission Electron ◽  
Feeding Area ◽  
Palisade Cells

White apple leafhopper (WALH; Typhlocyba pomaria McAtee) feeding damage on apple (Malus domestica Borkh.) leaves was examined with scanning and transmission electron microscopy. WALH created feeding holes in the (lower) abaxial epidermis, with no visible exterior evidence of cell injury to the adaxial (upper) epidermis. Feeding holes were located in areas of the leaf with high stomatal density and were near stomata. Groups of cells in the palisade layers were empty or contained coagulated cell contents. Adjacent, apparently noninjured, palisade cells contained an abundance of starch granules, possibly indicating that photoassimilate export was impaired. Spongy mesophyll cells abaxial to the feeding area were left intact as were the epidermal cells adaxial to the feeding area. External views of either epidermis and internal leaf views of injured cells indicated no cell wall collapse.

scholarly journals Differential shrinkage of mesophyll cells in transpiring cotton leaves: implications for static and dynamic pools of water, and for water transport pathways

2012 ◽  
Vol 39 (2) ◽  
pp. 91 ◽  
Author(s):  
Martin Canny ◽  
Suan Chin Wong ◽  
Cheng Huang ◽  
Celia Miller
Keyword(s):  
Gossypium Hirsutum L ◽  
Mesophyll Cells ◽  
Transport Pathways ◽  
Spongy Mesophyll ◽  
Structural Rigidity ◽  
Relative Water ◽  
Differential Shrinkage ◽  
Palisade Cells ◽  
Leaf Volume ◽  
Scanning Electron

Shrinkage of palisade cells during transpiration, previously measured for sclerophyllous leaves of Eucalyptus where cells shrank equally, was compared with shrinkage in thin mesophytic leaves of cotton (Gossypium hirsutum L.). Selected vapour pressure differences (Δe) from 0.6 to 2.7 kPa were imposed during steady-state photosynthesis and transpiration. Leaves were then cryo-fixed and cryo-planed paradermally, and images obtained with a cryo-scanning electron microscope (CSEM). Diameters of palisade ‘cavity cells’ within sub-stomatal cavities, and surrounding palisade ‘matrix cells’ were measured on CSEM images. Cavity and spongy mesophyll cells shrank progressively down to Δe = 2.7 kPa, while matrix cells remained at the same diameter at all Δe. Diameters were also measured of cavity and matrix cells quasi-equilibrated with relative humidities (RHs) from 100% to 86%. In leaves quasi-equilibrated with 95% RH, the cavity cells shrank so much as to be almost unmeasurable, while matrix cells shrank by only 6%. These data suggest that there are two distinct pools of water in cotton leaves: cavity plus spongy mesophyll cells (two-thirds of leaf volume) which easily lose water; and matrix cells (one-third of leaf volume), which retain turgor down to relative water loss = 0.4, providing structural rigidity to prevent wilting. This phenomenon is probably widespread among mesophytic leaves.

scholarly journals Histological Study of Some Echium vulgare, Pulmonaria officinalis and Symphytum officinale Populations

2011 ◽  
Vol 6 (10) ◽  
pp. 1934578X1100601 ◽  
Author(s):  
Nóra Papp ◽  
Tímea Bencsik ◽  
Kitti Németh ◽  
Kinga Gyergyák ◽  
Alexandra Sulc ◽  
...  
Keyword(s):  
Histological Study ◽  
Cell Number ◽  
Epidermal Cells ◽  
Mesophyll Cells ◽  
Leaf Mesophyll ◽  
Symphytum Officinale ◽  
Radial Cell ◽  
Palisade Cells ◽  
Reported Data ◽  
Ecological Habitats

Plants living in different ecological habitats can show significant variability in their histological and phytochemical characters. The main histological features of various populations of three medicinal plants from the Boraginaceae family were studied. Stems, petioles and leaves were investigated by light microscopy in vertical and transverse sections. The outline of the epidermal cells, as well as the shape and cell number of trichomes was studied in leaf surface casts. Differences were measured among the populations of Echium vulgare in the width and height of epidermis cells in the stem, petiole and leaf, as well as in the size of palisade cells in the leaves. Among the populations of Pulmonaria officinalis significant differences were found in the length of trichomes and in the slightly or strongly wavy outline of epidermal radial cell walls. Populations of Symphytum officinale showed variance in the height of epidermal cells in leaves and stems, length of palisade cells and number of intercellular spaces in leaves, and the size of the central cavity in the stem. Boraginaceae bristles were found to be longer in plants in windy/shady habitats as opposed to sunny habitats, both in the leaves and stems of P. officinalis and S. officinale, which might be connected to varying levels of exposure to wind. Longer epidermal cells were detected in the leaves and stems of both E. vulgare and S. officinale plants living in shady habitats, compared with shorter cells in sunny habitats. Leaf mesophyll cells were shorter in shady habitats as opposed to longer cells in sunny habitats, both in E. vulgare and S. officinale. This combination of histological characters may contribute to the plant's adaptation to various amounts of sunshine. The reported data prove the polymorphism of the studied taxa, as well as their ability to adapt to various ecological circumstances.

scholarly journals Leaf structural adaptations of two Limonium miller (Plumbaginales, Plumbaginaceae) taxa

2013 ◽  
pp. 43-54 ◽  
Author(s):  
Lana Zoric ◽  
Goran Anackov ◽  
Dunja Karanovic ◽  
Jadranka Lukovic
Keyword(s):  
Epidermal Cells ◽  
High Dimensions ◽  
Salt Glands ◽  
Abaxial Epidermis ◽  
Mesophyll Cells ◽  
Saline Habitats ◽  
Flat Cell ◽  
Palisade Cells ◽  
Limonium Gmelinii ◽  
Structural Adaptations

Limonium gmelinii (Willd.) O. Kuntze 1891 subsp. hungaricum (Klokov) So? is Pannonian endemic subspecies that inhabits continental halobiomes, while Limonium anfractum (Salmon) Salmon 1924 is one of the indicators of halophyte vegetation of marine rocks and its distribution is restricted to the southern parts of Mediterranean Sea coast. In this work, micromorphological and anatomical characters of leaves of these two Limonium taxa were analyzed, in order to examine their adaptations to specific environmental conditions on saline habitats. The results showed that both taxa exhibited strong xeromorphic adaptations that reflected in flat cell walls of epidermal cells, thick cuticle, high palisade/spongy tissue ratio, high index of palisade cells, the presence of sclereid idioblasts in leaf mesophyll and mechanical tissue by phloem and xylem. Both taxa are crynohalophytes and have salt glands on adaxial and abaxial epidermis for excretion of surplus salt. Relatively high dimensions of mesophyll cells, absence of non-glandular hairs and unprotected stomata slightly increased above the level of epidermal cells, are also adaptations to increased salinity.

scholarly journals THE STRUCTURE OF THE PRIMARY EPIDERMAL CELL WALL OF AVENA COLEOPTILES

1957 ◽  
Vol 3 (2) ◽  
pp. 171-182 ◽  
Author(s):  
S. T. Bayley ◽  
J. R. Colvin ◽  
F. P. Cooper ◽  
Cecily A. Martin-Smith
Keyword(s):  
Cell Wall ◽  
Outer Wall ◽  
Epidermal Cells ◽  
Cellulose Microfibrils ◽  
X Rays ◽  
Primary Wall ◽  
Normal Type ◽  
Number Of Layers ◽  
Angle Scattering ◽  
Epidermal Cell Wall

The primary walls of epidermal cells in Avena coleoptiles ranging in length from 2 to 40 mm. have been studied in the electron and polarizing microscopes and by the low-angle scattering of x-rays. The outer walls of these cells are composed of multiple layers of cellulose microfibrils oriented longitudinally; initially the number of layers is between 10 and 15 but this increases to about 25 in older tissue. Where epidermal cells touch, these multiple layers fuse gradually into a primary wall of the normal type between cells. In these radial walls, the microfibrils are oriented transversely. Possible mechanisms for the growth of the multilayered outer wall during cell elongation are discussed.

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