CsiLAC4 modulates boron flow in Arabidopsis and Citrus via high‐boron‐dependent lignification of cell walls

Tolerance to high boron concentration in Brassica rapa was primarily due to low net boron uptake by the roots. However, in the two tolerant genotypes, 39–43% of boron uptake was retained in the tap roots, which limited boron accumulation in the leaves, and also contributed to boron tolerance. In the sensitive genotype, 99% of the increase in boron uptake caused by high soil boron accumulated in the leaves, particularly in the leaf margins. Despite higher transpiration rates, lower net boron uptake occurred in the tolerant genotypes. This result cannot be explained by passive boron uptake alone. Active boron efflux was probably responsible for differences in net boron uptake among tolerant and sensitive genotypes. Boron concentration was much lower in the cell walls than in the cell sap of leaves, indicating that storage of boron in the cell walls was not a tolerance mechanism. Despite high boron concentrations in the leaf symplasm, rates of photosynthesis, transpiration and growth were almost unaffected in the tolerant genotypes. The results demonstrate that boron tolerance in Brassica rapa involves boron exclusion at the root level, boron partitioning away from leaves and, as boron accumulates in leaves despite the first two mechanisms, boron tolerance of the leaf tissue itself.

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Ectodesmata as Revealed By Freeze-Etch Preparations of Plant Epidermal Cell Walls

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100072782 ◽

1973 ◽

Vol 31 ◽

pp. 468-469

Author(s):

N.C. Lyon ◽

W. C. Mueller

Keyword(s):

Electron Microscopy ◽

Acetic Acid ◽

Nitric Acid ◽

Oxalic Acid ◽

Light Microscopy ◽

Epidermal Cell ◽

Cell Walls ◽

Plant Viruses ◽

Plant Leaves ◽

Thin Sections

Schumacher and Halbsguth first demonstrated ectodesmata as pores or channels in the epidermal cell walls in haustoria of Cuscuta odorata L. by light microscopy in tissues fixed in a sublimate fixative (30% ethyl alcohol, 30 ml:glacial acetic acid, 10 ml: 65% nitric acid, 1 ml: 40% formaldehyde, 5 ml: oxalic acid, 2 g: mecuric chloride to saturation 2-3 g). Other workers have published electron micrographs of structures transversing the outer epidermal cell in thin sections of plant leaves that have been interpreted as ectodesmata. Such structures are evident following treatment with Hg++ or Ag+ salts and are only rarely observed by electron microscopy. If ectodesmata exist without such treatment, and are not artefacts, they would afford natural pathways of entry for applied foliar solutions and plant viruses.

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An ultrastructural study of vegetative incompatibility in plants

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100083047 ◽

1978 ◽

Vol 36 (2) ◽

pp. 436-437

Author(s):

Randy Moore

Keyword(s):

Ultrastructural Study ◽

Cell Walls ◽

Growth And Development ◽

Solanum Pennellii ◽

Initial Product ◽

Basic Aspect ◽

Tissue Interactions ◽

Graft Interface ◽

Antigen Antibody ◽

Standard Fixation

Cell and tissue interactions are a basic aspect of eukaryotic growth and development. While cell-to-cell interactions involving recognition and incompatibility have been studied extensively in animals, there is no known antigen-antibody reaction in plants and the recognition mechanisms operating in plant grafts have been virtually neglected.An ultrastructural study of the Sedum telephoides/Solanum pennellii graft was undertaken to define possible mechanisms of plant graft incompatibility. Grafts were surgically dissected from greenhouse grown plants at various times over 1-4 weeks and prepared for EM employing variations in the standard fixation and embedding procedure. Stock and scion adhere within 6 days after grafting. Following progressive cell senescence in both Sedum and Solanum, the graft interface appears as a band of 8-11 crushed cells after 2 weeks (Fig. 1, I). Trapped between the buckled cell walls are densely staining cytoplasmic remnants and residual starch grains, an initial product of wound reactions in plants.

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Comparison of Substructures Between Uniaxial and Biaxial Deformation in 1100-0 Aluminum

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100096989 ◽

1981 ◽

Vol 39 ◽

pp. 52-53

Author(s):

D. L. Rohr ◽

S. S. Hecker

Keyword(s):

Plastic Strain ◽

Cell Walls ◽

Room Temperature ◽

Mechanical Response ◽

Biaxial Tension ◽

Initial Deformation ◽

Uniaxial Deformation ◽

Biaxial Deformation ◽

Stress States ◽

Comprehensive Study

As part of a comprehensive study of microstructural and mechanical response of metals to uniaxial and biaxial deformations, the development of substructure in 1100 A1 has been studied over a range of plastic strain for two stress states.Specimens of 1100 aluminum annealed at 350 C were tested in uniaxial (UT) and balanced biaxial tension (BBT) at room temperature to different strain levels. The biaxial specimens were produced by the in-plane punch stretching technique. Areas of known strain levels were prepared for TEM by lapping followed by jet electropolishing. All specimens were examined in a JEOL 200B run at 150 and 200 kV within 24 to 36 hours after testing.The development of the substructure with deformation is shown in Fig. 1 for both stress states. Initial deformation produces dislocation tangles, which form cell walls by 10% uniaxial deformation, and start to recover to form subgrains by 25%. The results of several hundred measurements of cell/subgrain sizes by a linear intercept technique are presented in Table I.

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Cryosectioning plant roots prepared by high-pressure freezing

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100127748 ◽

1987 ◽

Vol 45 ◽

pp. 662-663

Author(s):

R.E. Crang ◽

M. Mueller ◽

K. Zierold

Keyword(s):

High Pressure ◽

Cell Walls ◽

Plant Tissues ◽

Ice Crystal ◽

High Pressure Freezing ◽

Vitreous State ◽

Radial Depth ◽

Irregular Topography ◽

Considerable Depth ◽

Conventional Freezing

Obtaining frozen-hydrated sections of plant tissues for electron microscopy and microanalysis has been considered difficult, if not impossible, due primarily to the considerable depth of effective freezing in the tissues which would be required. The greatest depth of vitreous freezing is generally considered to be only 15-20 μm in animal specimens. Plant cells are often much larger in diameter and, if several cells are required to be intact, ice crystal damage can be expected to be so severe as to prevent successful cryoultramicrotomy. The very nature of cell walls, intercellular air spaces, irregular topography, and large vacuoles often make it impractical to use immersion, metal-mirror, or jet freezing techniques for botanical material.However, it has been proposed that high-pressure freezing (HPF) may offer an alternative to the more conventional freezing techniques, inasmuch as non-cryoprotected specimens may be frozen in a vitreous, or near-vitreous state, to a radial depth of at least 0.5 mm.

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Characterization of machined polystyrene foam

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010015383x ◽

1989 ◽

Vol 47 ◽

pp. 372-373

Author(s):

C. W. Price ◽

E. F. Lindsey ◽

R. M. Franks ◽

M. A. Lane

Keyword(s):

Surface Finish ◽

Cell Walls ◽

Surface Structures ◽

Efficient Technique ◽

Low Density ◽

Polystyrene Foam ◽

Planar Surfaces ◽

Machining Characteristics

Diamond-point turning is an efficient technique for machining low-density polystyrene foam, and the surface finish can be substantially improved by grinding. However, both diamond-point turning and grinding tend to tear and fracture cell walls and leave asperities formed by agglomerations of fragmented cell walls. Vibratoming is proving to be an excellent technique to form planar surfaces in polystyrene, and the machining characteristics of vibratoming and diamond-point turning are compared.Our work has demonstrated that proper evaluation of surface structures in low density polystyrene foam requires stereoscopic examinations; tilts of + and − 3 1/2 degrees were used for the stereo pairs. Coating does not seriously distort low-density polystyrene foam. Therefore, the specimens were gold-palladium coated and examined in a Hitachi S-800 FESEM at 5 kV.

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Exploration of cell wall architecture with the rapid-freeze deep-etch technique

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100146485 ◽

1993 ◽

Vol 51 ◽

pp. 128-129

Author(s):

Béatrice Satiat-Jeunemaitre ◽

Chris Hawes

Keyword(s):

Plant Cell ◽

Cell Walls ◽

Cell Biology ◽

Molecular Model ◽

Three Dimensional ◽

Secretory Activity ◽

Wall Structure ◽

Specimen Preparation ◽

Molecular Architecture ◽

Plant Cell Walls

The comprehension of the molecular architecture of plant cell walls is one of the best examples in cell biology which illustrates how developments in microscopy have extended the frontiers of a topic. Indeed from the first electron microscope observation of cell walls it has become apparent that our understanding of wall structure has advanced hand in hand with improvements in the technology of specimen preparation for electron microscopy. Cell walls are sub-cellular compartments outside the peripheral plasma membrane, the construction of which depends on a complex cellular biosynthetic and secretory activity (1). They are composed of interwoven polymers, synthesised independently, which together perform a number of varied functions. Biochemical studies have provided us with much data on the varied molecular composition of plant cell walls. However, the detailed intermolecular relationships and the three dimensional arrangement of the polymers in situ remains a mystery. The difficulty in establishing a general molecular model for plant cell walls is also complicated by the vast diversity in wall composition among plant species.

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Silicification of wood-cell walls

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100169870 ◽

1994 ◽

Vol 52 ◽

pp. 428-429

Author(s):

S. E. Keckler ◽

D. M. Dabbs ◽

N. Yao ◽

I. A. Aksay

Keyword(s):

Electron Microscopy ◽

Cell Wall ◽

Cell Walls ◽

Lignin Content ◽

Resin Composite ◽

Middle Lamella ◽

Cellulose Fibers ◽

Complex Structures ◽

Rich Region ◽

Inorganic Precursors

Cellular organic structures such as wood can be used as scaffolds for the synthesis of complex structures of organic/ceramic nanocomposites. The wood cell is a fiber-reinforced resin composite of cellulose fibers in a lignin matrix. A single cell wall, containing several layers of different fiber orientations and lignin content, is separated from its neighboring wall by the middle lamella, a lignin-rich region. In order to achieve total mineralization, deposition on and in the cell wall must be achieved. Geological fossilization of wood occurs as permineralization (filling the void spaces with mineral) and petrifaction (mineralizing the cell wall as the organic component decays) through infiltration of wood with inorganics after growth. Conversely, living plants can incorporate inorganics into their cells and in some cases into the cell walls during growth. In a recent study, we mimicked geological fossilization by infiltrating inorganic precursors into wood cells in order to enhance the properties of wood. In the current work, we use electron microscopy to examine the structure of silica formed in the cell walls after infiltration of tetraethoxysilane (TEOS).

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