The morphology of grain abscission in Zizania aquatica

1980 ◽  
Vol 58 (21) ◽  
pp. 2269-2273 ◽  
Author(s):  
H. B. Hanten ◽  
G. E. Ahlgren ◽  
J. B. Carlson
Keyword(s):  
Wild Rice ◽  
Cell Walls ◽  
Vascular Tissue ◽  
Embryo Sac ◽  
Middle Lamella ◽  
Abscission Zone ◽  
Rice Grains ◽  
Zizania Aquatica ◽  
Parenchyma Cells ◽  
Anatomical Evidence

The anatomical development of the abscission zone in grains of Zizania aquatica L. was correlated with development of the embryo. The abscission zone is well developed when the embryo sac is mature. Soon after pollination, the first anatomical evidence of abscission appears as plasmolysis of the separation layer parenchyma cells. This is followed by separation of the layers by dissolution of the middle lamella and fragmentation of cell walls. Persistence of intact vascular tissue and presence of a surrounding cone-shaped mass of lignified cells may be involved in abscission of wild rice grains.

Ultrastructural Changes in the Cell Walls of Cambial Derivatives During Wood Formation in Indian ELM (Holoptelea Integrifolia)

IAWA Journal ◽  
2012 ◽  
Vol 33 (4) ◽  
pp. 403-416 ◽  
Author(s):  
Karumanchi S. Rao ◽  
Yoon Soo Kim ◽  
Pramod Sivan
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Middle Lamella ◽  
Ultrastructural Changes ◽  
Cell Wall Polysaccharides ◽  
Lignin Distribution ◽  
Parenchyma Cells ◽  
Ray Cells ◽  
Xylem Elements ◽  
S2 Layer

Sequential changes occurring in cell walls during expansion, secondary wall (SW) deposition and lignification have been studied in the differentiating xylem elements of Holoptelea integrifolia using transmission electron microscopy. The PATAg staining revealed that loosening of the cell wall starts at the cell corner middle lamella (CCML) and spreads to radial and tangential walls in the zone of cell expansion (EZ). Lignification started at the CCML region between vessels and associated parenchyma during the final stages of S2 layer formation. The S2 layer in the vessel appeared as two sublayers,an inner one and outer one.The contact ray cells showed SW deposition soon after axial paratracheal parenchyma had completed it, whereas noncontact ray cells underwent SW deposition and lignification following apotracheal parenchyma cells. The paratracheal and apotracheal parenchyma cells differed noticeably in terms of proportion of SW layers and lignin distribution pattern. Fibres were found to be the last xylem elements to complete SW deposition and lignification with differential polymerization of cell wall polysaccharides. It appears that the SW deposition started much earlier in the middle region of the fibres while their tips were still undergoing elongation. In homogeneous lignin distribution was noticed in the CCML region of fibres.

A DEVELOPMENTAL STUDY OF WILD RICE, ZIZANIA AQUATICA L.

1960 ◽  
Vol 38 (5) ◽  
pp. 719-741 ◽  
Author(s):  
Cynthia E. Weir ◽  
Hugh M. Dale
Keyword(s):  
Wild Rice ◽  
Embryo Sac ◽  
Developmental Study ◽  
Abscission Layer ◽  
Potential Yield ◽  
Zizania Aquatica ◽  
History Of ◽  
Nuclear Changes ◽  
Well Differentiated ◽  
The Many

The life history of wild rice is traced from the appearance of the first submersed leaves in the spring until the seed of this annual plant is buried at the bottom of a lake in the fall. The characteristics of the three types of leaves are discussed. The change from the simple vegetative apex to the many-tipped, young inflorescence occurs early. Thus the potential yield in rice grains is determined as the tips of the upright leaves reach the surface of the water and before the stem elongates. The inflorescence develops acropetally as does each spikelet. Only at the later stages can the pistillate and staminate spikelets be distinguished. The development of the microspores and the nuclear changes in the embryo sac have been elucidated. In Zizania the embryo development has been found to be a variant of that found in Poa while the endosperm develops chiefly from the outside. A well-differentiated abscission layer develops at the base of each spikelet.

scholarly journals Chilling Injury in Peaches: A Cytochemical and Ultrastructural Cell Wall Study

1992 ◽  
Vol 117 (1) ◽  
pp. 114-118 ◽  
Author(s):  
J.G. Luza ◽  
R. van Gorsel ◽  
V.S. Polito ◽  
A.A. Kader
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Prunus Persica ◽  
Periodic Acid ◽  
Chilling Injury ◽  
Middle Lamella ◽  
Wall Structure ◽  
Positive Staining ◽  
Intercellular Matrix ◽  
Parenchyma Cells

Fruits of mid- (`O'Henry'), late (`Airtime'), and extra-late-season (`Autumn Gem') peach [Prunus persica (L.) Batsch] cultivars were examined for changes in cell wall structure and cytochemistry that accompany the onset of mealiness and leatheriness of the mesocarp due to chilling injury. The peaches were stored at 10C for up to 18 days or at SC for up to 29 days. Plastic-embedded sections were stained by the Schiff's-periodic acid reaction, Calcofluor white MR2, and Coriphosphine to demonstrate total insoluble carbohydrates, ß-1,4 glucans, and pectins, respectively. Mealiness was characterized by separation of mesocarp parenchyma cells leading to increased intercellular spaces and accumulation of pectic substances in the intercellular matrix. Little structural change was apparent in the cellulosic component of the cell walls of these fruits. In leathery peaches, the mesocarp parenchyma cells collapsed, intercellular space continued to increase, and pectin-positive staining in the intercellular matrix increased greatly. In addition, the component of the cell walls that stained positively for ß-1,4 glucans became thickened relative to freshly harvested or mealy fruit. At the ultrastructural level, dissolution of the middle lamella, cell separation, irregular thickening of the primary wall, and plasmolysis of the mesocarp parenchyma cells were seen as internal breakdown progressed.

scholarly journals VARIATIONS IN CELL WALL ULTRASTRUCTURE AND CHEMISTRY IN CELL TYPES OF EARLYWOOD AND LATEWOOD IN ENGLISH OAK (QUERCUS ROBUR)

IAWA Journal ◽  
2016 ◽  
Vol 37 (3) ◽  
pp. 383-401 ◽  
Author(s):  
Jong Sik Kim ◽  
Geoffrey Daniel
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Quercus Robur ◽  
Growth Ring ◽  
Middle Lamella ◽  
Cell Types ◽  
Parenchyma Cells ◽  
Ray Parenchyma ◽  
English Oak ◽  
Ray Parenchyma Cells

Although there is considerable information on anatomy and gross chemistry of oak wood, little is known on the ultrastructure and chemistry at the individual cell wall level. In particular, differences in ultrastructure and chemistry within the same cell type between earlywood (EW) and latewood (LW) are poorly understood. This study investigated the ultrastructure and chemistry of (vasicentric) tracheids, vessels, (libriform) fibers and axial/ray parenchyma cells of English oak xylem (Quercus robur L.) using light-, fluorescence- and transmission electron microscopy combined with histo/cytochemistry and immunohisto/ cytochemistry. EW tracheids showed several differences from LW tracheids including thinner cell walls, wider middle lamella cell corner (MLcc) regions and lesser amounts of mannan epitopes. Fibers showed thicker cell walls and higher amounts of mannan epitopes than tracheids. EW vessels were rich in guaiacyl (G) lignin with a characteristic non-layered cell wall organization (absence of S1–3 layers), whereas LW vessels were rich in syringyl (S) lignin with a three layered cell wall structure (S1–3 layers). Formation of a highly lignified and wide protective layer (PL) inside axial/ray parenchyma cells was detected only in EW. Distribution of mannan epitopes varied greatly between cell types and between EW and LW, whereas distribution of xylan epitopes was almost identical in all cell types within a growth ring. Together, this study demonstrates that there are great variations in ultrastructure and chemistry of cell walls within a single growth ring of English oak xylem.

Ultrastructure of wilt syndrome caused by Verticillium dahliae. V. Attempted localization of phenolic compounds in the vascular region

1978 ◽  
Vol 56 (20) ◽  
pp. 2594-2612 ◽  
Author(s):  
Jane Robb ◽  
J. D. Brisson ◽  
Lloyd Busch ◽  
B. C. Lu
Keyword(s):  
Phenolic Compounds ◽  
Ferric Chloride ◽  
Verticillium Dahliae ◽  
Cell Walls ◽  
Middle Lamella ◽  
Protective Layer ◽  
Multivesicular Body ◽  
Ferric Ion ◽  
Parenchyma Cells ◽  
Cytoplasmic Structures

Ferric chloride has been used in an attempt to detect phenolic compounds at the ultrastructure level in the petioles of chrysanthemums and sunflowers infected with Verticillium dahliae. The fungus contains two types of cytoplasmic structures which stain very densely with ferric chloride; one is similar to a multivesicular body, the other solid and apparently spherical. In treated chrysanthemums, the ferric ion accumulates mainly in vessel plugs, in laminar arrays or localized diffuse deposits in the secondary walls of vessels, in vasicentric parenchyma cells, and the protective layer of parenchyma cells immediately adjacent to the vessels. In treated sunflowers the ferric ion accumulates mainly in vessel plugs, in the pectinaceous layers of the cell wall (i.e. middle lamella and primary cell walls), and in the vasicentric parenchyma cells. Differences in the pattern of phenolic deposition in the two hosts could account wholly or in part for differences in symptom expression.

Variability in the Distribution of Middle Lamella Lignin in Secondary Vascular Tissues of Kenaf Stems

IAWA Journal ◽  
2014 ◽  
Vol 35 (1) ◽  
pp. 61-68
Author(s):  
Seung Gon Wi ◽  
Kwang Ho Lee ◽  
Hyeun Jong Bae ◽  
Byung Dae Park ◽  
Adya P. Singh
Keyword(s):  
Cell Walls ◽  
Secondary Xylem ◽  
Middle Lamella ◽  
Hibiscus Cannabinus ◽  
Secondary Phloem ◽  
Xylem Parenchyma ◽  
Vascular Tissues ◽  
Transmission Electron ◽  
Parenchyma Cells ◽  
Xylem Elements

Lignin in the middle lamella of the secondary xylem of angiosperms appears to be inhomogeneously distributed, based on studies where the focus is on a close examinantion of the middle lamella region of fibre cell walls by transmission electron microscopy (TEM). This is in contrast to the secondary xylem of gymnosperms which often display a more uniform distribution of lignin in the middle lamella of secondary xylem elements. The aim of our study was to undertake TEM examination of kenaf (Hibiscus cannabinus L.), an angiosperm plant mainly cultivated for its high quality secondary phloem fibres, to investigate lignin distribution in the middle lamella of secondary vascular tissues, including secondary phloem fibres. The middle lamella displayed considerable heterogeneity in the distribution of lignin in all lignified secondary vascular tissues, including xylem and phloem fibres, vessels and axial xylem parenchyma cells. The results provided evidence of lignin inhomogeneity in the secondary phloem fibres as well as in other lignified elements of kenaf vascular tissues, extending previous observations which were confined only to fibre cells.

The Massaria disease of plane trees:its wood decay mechanism

IAWA Journal ◽  
2014 ◽  
Vol 35 (4) ◽  
pp. 395-406 ◽  
Author(s):  
Uwe Schmitt ◽  
Benjamin Lüer ◽  
Dirk Dujesiefken ◽  
Gerald Koch
Keyword(s):  
Cell Walls ◽  
Parenchyma Cell ◽  
Middle Lamella ◽  
Wood Decay ◽  
Cell Types ◽  
Cell Corner ◽  
Transmission Electron ◽  
Parenchyma Cells ◽  
Decay Pattern

Branches of Platanus × hispanica with distinct symptoms of the Massaria disease were investigated by light and transmission electron microscopy and cellular UVmicrospectrophotometry. The samples collected in the city of Mannheim, Germany, were infected in vivo with the fungus Splanchnonema platani and showed various degrees of wood decay. The investigations were focused on the decay pattern of cell walls in the different cells, i.e., fibres, vessels as well as ray and axial parenchyma cells. The following results were obtained. Hyphae of the ascomycete fungus Splanchnonema platani penetrated from cell to cell through the pits and not through the cell wall middle lamella, by the formation of thin perforation hyphae. During this process, the 1–5 μm thick hyphae became narrower without attacking the wall around the pit canal. After penetration through a pit, the hyphae again enlarged to their original diameter. This is true for all pit pairs connecting the various cell types. Late decay stages did not show a decay of cell corner regions and middle lamellae of fibres as well as vessel and parenchyma cell walls. Phenolic deposits in parenchyma cells were still present in severely attacked xylem tissue. These features point to a low lignolytic capacity of the fungus. The frequently found microscopic decay pattern with the formation of oval or spherical cavities in the S2 layer of the secondary wall with an often structurally intact S3 layer is a characteristic of softrot decay. This classification is also supported by the remaining cell corner and middle lamella regions in advanced decay stages. As a consequence of this decay type, branches fracture in a brittle mode.

scholarly journals The impact of natural and artificial weathering on the anatomy of selected tropical hardwoods

IAWA Journal ◽  
2020 ◽  
Vol 41 (3) ◽  
pp. 333-355 ◽  
Author(s):  
Miroslava Mamoňová ◽  
Ladislav Reinprecht
Keyword(s):  
Cell Walls ◽  
Parenchyma Cell ◽  
Middle Lamella ◽  
Artificial Weathering ◽  
Hymenaea Courbaril ◽  
Anatomical Changes ◽  
Micro Cracks ◽  
Parenchyma Cells ◽  
Dipteryx Odorata ◽  
The Impact

Abstract The effect of natural and artificial weathering on the anatomy of seven tropical hardwoods: Bangkirai (Shorea obtusa Wall.), Cumaru (Dipteryx odorata (Aubl.) Wild.), Cumaru Rosa (Dipteryx magnifica (Ducke) Ducke), Ipé (Tabebuia serratifolia Nichols.), Jatobá (Hymenaea courbaril L.), Kusia (Nauclea diderrichii Merill) and Massaranduba (Manilkara bidentata A. Chev.), was studied. As a result of weathering some characteristic anatomical changes occurred: the weakening of connections between cell elements related to the degradation of the middle lamella; micro-cracks in cell walls; total degradation of parenchyma cells in xylem rays, or significant thinning of parenchyma cell walls and their extreme shrinkage; micro-cracks in the vicinity of xylem rays; significant transversal disruptions in libriform fibres; ablation of pit membranes in vessels and parenchyma cells; changes in the secondary wall of libriform fibres, for example, their defibrillation and weathering-degradation of the S1 layer; and spherical formations on the S3 layer of cell walls produced from condensing compounds of degraded lignin and hemicelluloses as well as thermo-mechanical wrinkling. The highest incidence of micro-cracks after both modes of weathering was found in the densest species; Cumaru, Ipé, and Massaranduba.

scholarly journals Anatomy of ethylene-induced floral-organ abscission in Chamelaucium uncinatum (Myrtaceae)

2005 ◽  
Vol 53 (2) ◽  
pp. 119 ◽  
Author(s):  
Andrew J. Macnish ◽  
Donald E. Irving ◽  
Daryl C. Joyce ◽  
Vasanthe Vithanage ◽  
Alan H. Wearing
Keyword(s):  
Cell Walls ◽  
Floral Development ◽  
Middle Lamella ◽  
Floral Organ ◽  
Abscission Zone ◽  
Adjacent Cell ◽  
Flower Buds ◽  
Floral Tube ◽  
Exogenous Ethylene ◽  
Chamelaucium Uncinatum

Postharvest abscission of Geraldton waxflower (Chamelaucium uncinatum Schauer) flower buds and flowers is ethylene-mediated. Exposure of floral organs to exogenous ethylene (1 µL L–1) for 6 h at 20°C induced separation at a morphologically and anatomically distinct abscission zone between the pedicel and floral tube. Flower buds with opening petals and flowers with a nectiferous hypanthium were generally more responsive to exogenous ethylene than were flower buds enclosed in shiny bracteoles and aged (senescing) flowers. The anatomy of abscission-zone cells did not change at sequential stages of floral development from immature buds to aged flowers. The zone comprised a layer of small, laterally elongated-to-rounded, closely packed and highly protoplasmic parenchyma cells. Abscission occurred at a two- to four-cell-wide separation layer within the abscission zone. The process involved degradation of the middle lamella between separation layer cells. Following abscission, cells on both the proximal and distal faces of the separation layer became spherical, loosely packed and contained degenerating protoplasm. Central vascular tissues within the surrounding band of separation layer cells became torn and fractured. For flower buds, bracteoles that enclose the immature floral tube also separated at an abscission zone. However, this secondary abscission zone appeared less sensitive to ethylene than the primary (central) floral-tube abscission zone as bracteoles generally only completely abscised when exposed to 10 µL L–1 ethylene for the longer period of 24 h at 20°C. The smooth surfaces of abscised separation-layer cells suggest that hydrolase enzymes degrade the middle lamella between adjacent cell walls.

Silicification of wood-cell walls

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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