scholarly journals Ultrastructural changes in aster yellows phytoplasma affected Limonium sinuatum Mill. plants.I Pathology of conducting tissues

2014 ◽  
Vol 70 (3) ◽  
pp. 173-180 ◽  
Author(s):  
Anna Rudzińska-Langwald ◽  
Maria Kamińska
Keyword(s):  
Endoplasmic Reticulum ◽  
Structural Changes ◽  
Sieve Tube ◽  
Sieve Element ◽  
Ultrastructural Changes ◽  
Sieve Elements ◽  
Aster Yellows ◽  
Parenchyma Cells ◽  
Sieve Tubes ◽  
Aster Yellows Phytoplasma

Changes in anatomy and cytology of conducting tissues of <em>Limonium sinuatum</em> Mill. plants affected by aster yellows phytoplasma were investigated. In the phloem tissues of affected plants stem necrosis takes place. In necrotic regions no sieve tubes were observed only necrotic cells and parenchyma cells. The sieve tubes present on the border of necrosis showed collapsed walls and were rich in vesicles. Phytoplasma cells were observed in sieve tubes present in nonnecrotic regions of the phloem. Various structural changes in sieve elements were investigated. The endoplasmic reticulum cistemae were often localised in the lumen of the sieve element without contact with the walls. Such localisation of endoplasmic reticulum was never observed in healthy plants. Vesicles of different size, fuzzy material and clumping of p-proteins were characteristic for sieve elements from nonnecrotic part of phloem. No correlation with the sieve tube structure and the appearance of phytoplasma in a single sieve element was found. In control plants of <em>L. sinuatum</em> phloem observed were phloem parenchyma cells with spiny vesicles (SV). In infected plants there were a remarkable increase in cells with SV. Also the SV itself had not only a vesicular but also a tubular or extended cistern shape.

scholarly journals Changes of ultrastructure and cytoplasmic free calcium in Gladiolus x hybridus Van Houtte roots infected by aster yellows phytoplasma

2011 ◽  
Vol 72 (4) ◽  
pp. 269-282 ◽  
Author(s):  
Anna Rudzińska-Langwald ◽  
Maria Kamińska
Keyword(s):  
Calcium Ions ◽  
Infected Plant ◽  
Sieve Tube ◽  
Plant Roots ◽  
Free Calcium ◽  
Aster Yellows ◽  
Companion Cells ◽  
Parenchyma Cells ◽  
Sieve Tubes ◽  
Aster Yellows Phytoplasma

Roots of <em>Gladiolus </em>x <em>hybridus </em>Van Houtte plants infected with aster yellows phytoplasma were examined. The infected plants had a reduced root system in comparison to control plants. Their roots were thinner and the stele organisation was changed. Phytoplasmas were present in sieve tubes, companion cells and phloem parenchyma cells of the infected plant roots. Free calcium ions were localized in the cells of infected plants. Cells of the stele of infected roots, especially these infected with phytoplasmas, showed an increase of calcium antimonite deposits in theirs protoplasts. Also the number of calcium antimonite deposits increased in sieve tubes of infected roots. The deposits were present on plasma membrane, around the sieve tube plate and also in the lumen of the sieve tube. The increase of free calcium ions in sieve tubes did not cause the occlusion of sieve tube pores. Companion cells and some parenchyma cells with phytoplasmas did not react to phytoplasma infection with an increase of Ca<sup>2+</sup> ions in protoplast. The parenchyma cells showing signs of degeneration reacted with high increase of calcium ions. The Ca<sup>2+</sup> ions were present mainly in cytoplasm of infected parenchyma cells. There were calcium antimonite deposits in infected plant roots xylem elements and in intracellular spaces of cortex parenchyma. Such deposits were not present in control plants.

scholarly journals RELATION OF BEET YELLOWS VIRUS TO THE PHLOEM AND TO MOVEMENT IN THE SIEVE TUBE

1967 ◽  
Vol 32 (1) ◽  
pp. 71-87 ◽  
Author(s):  
K. Esau ◽  
J. Cronshaw ◽  
L. L. Hoefert
Keyword(s):  
Sieve Tube ◽  
Plant Viruses ◽  
Passive Transport ◽  
Sieve Elements ◽  
Virus Particles ◽  
Parenchyma Cells ◽  
Beet Yellows Virus ◽  
Sieve Tubes ◽  
Sieve Plates ◽  
Orderly Arrangement

In minor veins of leaves of Beta vulgaris L. (sugar beet) yellows virus particles were found both in parenchyma cells and in mature sieve elements. In parenchyma cells the particles were usually confined to the cytoplasm, that is, they were absent from the vacuoles. In the sieve elements, which at maturity have no vacuoles, the particles were scattered throughout the cell. In dense aggregations the particles tended to assume an orderly arrangement in both parenchyma cells and sieve elements. Most of the sieve elements containing virus particles had mitochondria, plastids, endoplasmic reticulum, and plasma membrane normal for mature sieve elements. Some sieve elements, however, showed evidence of degeneration. Virus particles were present also in the pores of the sieve plates, the plasmodesmata connecting the sieve elements with parenchyma cells, and the plasmodesmata between parenchyma cells. The distribution of the virus particles in the phloem of Beta is compatible with the concept that plant viruses move through the phloem in the sieve tubes and that this movement is a passive transport by mass flow. The observations also indicate that the beet yellows virus moves from cell to cell and in the sieve tube in the form of complete particles, and that this movement may occur through sieve-plate pores in the sieve tube and through plasmodesmata elsewhere.

scholarly journals Ultrastructural changes in aster yellows phytoplasma affected Limonium sinuatum Mill. plants II. Pathology of cortex parenchyma cells

2014 ◽  
Vol 70 (4) ◽  
pp. 273-279 ◽  
Author(s):  
Anna Rudzińska-Langwald ◽  
Maria Kamińska
Keyword(s):  
Plasma Membrane ◽  
Ultrastructural Changes ◽  
Internal Space ◽  
Pathological Changes ◽  
Aster Yellows ◽  
Parenchyma Cells ◽  
Aster Yellows Phytoplasma

In <em>Limonium sinuatum</em> Mill, plants with severe symptoms of aster yellows infection phytoplasmas were present not only in the phloem but also in some cortex parenchymas cells. These parenchyma cells were situated at some distance from the conducting bundles. The phytoplasmas were observed directly in parenchyma cells cytoplasm. The number of phytoplasmas present in each selected cell varies. The cells with a small number of phytoplasmas show little pathological changes compared with the unaffected cells of the same zone of the stem as well with the cells of healthy plants. The cells filled with a number of phytoplasmas had their protoplast very much changed. The vacuole was reduced and in the cytoplasm a reduction of the number of ribosomes was noted and regions of homogenous structure appeared. Mitochondria were moved in the direction of the tonoplast and plasma membrane. Compared to the cells unaffected by phytoplasma, the mitochondria were smaller and had an enlarged cristae internal space. The chloroplasts from affected cells had a very significant reduction in size and the tylacoids system had disappeared. The role of these changes for creating phytoplasma friendly enviroment is discused.

Proteins in the sieve element-companion cell complexes: their detection, localization and possible functions

2000 ◽  
Vol 27 (6) ◽  
pp. 489 ◽  
Author(s):  
Hiroaki Hayashi ◽  
Akari Fukuda ◽  
Nobuo Suzui ◽  
Shu Fujimaki
Keyword(s):  
Sieve Tube ◽  
Soluble Proteins ◽  
Sieve Element ◽  
Tissue Extract ◽  
Companion Cell ◽  
Phloem Sap ◽  
Sieve Elements ◽  
Cell Complexes ◽  
Companion Cells ◽  
Sieve Tubes

Many kinds of proteins have been found in the sieve element–companion cell complexes by the analyses of phloem sap and microscopic observations. The cDNAs, which encode some of these sieve-tube proteins, have already been cloned. As mature sieve elements lack nuclei and most ribosomes, sieve-tube proteins have been hypothesized to be synthesized in the companion cells and then transported to the lumina of the functional sieve tubes through the plasmodesmata connecting the companion cells and sieve elements. Soluble proteins present in the sieve tubes can be collected by several techniques, such as incision or the aphid technique. The composition of the proteins in the phloem sap is unique compared with that of tissue extract, suggesting these proteins have important roles for the development and functions of sieve tubes.

The secondary phloem of Austrobaileya scandens

1970 ◽  
Vol 48 (2) ◽  
pp. 341-359 ◽  
Author(s):  
Lalit M. Srivastava
Keyword(s):  
Tannic Acid ◽  
Cross Sections ◽  
Significant Proportion ◽  
Sieve Tube ◽  
Secondary Phloem ◽  
Sieve Elements ◽  
Sieve Cells ◽  
Companion Cells ◽  
Parenchyma Cells ◽  
Definition Of

The origin of sieve elements and parenchyma cells in the secondary phloem of Austrobaileya was studied by use of serial cross sections stained with tannic acid – ferric chloride and lacmoid. In three important respects, Austrobaileya phloem recalls gymnospermous features: it has sieve cells rather than sieve-tube members; a significant proportion of sieve elements and companion cells arise independently of each other; and sieve areas occur between sieve elements and companion cells ontogenetically unrelated to each other. The angiospermous feature includes origin of most sieve elements and parenchyma, including companion cells, after divisions in phloic initials. In these instances companion cells show a closer ontogenetic relationship to sieve elements than do other parenchyma cells. The combination of gymnospermous and angiospermous features makes phloem of Austrobaileya unique when compared to that of all those species that have been investigated in detail. It is further suggested that the term albuminous cells is inappropriate and should be replaced by companion cells but that the ontogenetic relationship implicit in the definition of companion cells is too restrictive and should be abandoned.

Vascular system of the floret of Alopecurus carolinianus (Gramineae)

1987 ◽  
Vol 65 (12) ◽  
pp. 2592-2600 ◽  
Author(s):  
Thompson Demetrio Pizzolato
Keyword(s):  
Vascular System ◽  
Sieve Tube ◽  
Sieve Element ◽  
Sieve Elements

The interconnecting vascular system of the floret of Alopecurus carolinianus Walter begins as a single, collateral bundle, which enters the rachilla and becomes reorganized into a diarch pattern while ascending between the glumes. During a pronounced posterior enlargement, the rachilla bundle becomes connected with the median and four lateral bundles of the lemma. Above the trace to the lemma median, elements of a xylem discontinuity surrounded by those of a sieve-element plexus form in the rachilla bundle. Higher, a trace consisting of elements of the xylem discontinuity and the plexus enters the anterior and the posterior stamen. Two bundles, the lowest portion of the pistil vasculature, rise eccentrically from the xylem discontinuity and sieve-element plexus at the level of the stamen traces. The bundles condense into one which rotates counterclockwise and connects with the anterior sieve tube of the pistil. The xylem discontinuity of the bundle now in the pistil begins to diminish, and the sieve elements fan out to the sides and posterior of the xylem discontinuity. From the sieve elements one or two posterolaterals emerge toward the styles. The bundle of diffuse sieve elements in a semicircle behind the diminishing xylem discontinuity is now the placental bundle of the pistil. After its xylem discontinuity and then its sieve elements fade out, the placental bundle merges with the ovule at the chalaza.

Fine structure of the phloem of Pisum sativum. I. The sieve element ontogeny

1965 ◽  
Vol 13 (2) ◽  
pp. 171 ◽  
Author(s):  
MC Wark ◽  
TC Chambers
Keyword(s):  
Endoplasmic Reticulum ◽  
Pisum Sativum ◽  
Nuclear Material ◽  
Sieve Element ◽  
Secondary Phloem ◽  
Sieve Elements ◽  
Pisum Sativum L ◽  
Ontogenetic Study ◽  
Sieve Plates ◽  
Peripheral Cytoplasm

An ontogenetic study of secondary phloem sieve elements of Pisum sativum L., fixed on the intact plant for electron microscopy, indicates that the connecting strands across the sieve plates are continuities of the endoplasmic reticulum. Each connecting strand is surrounded by a callose cylinder. The peripheral cytoplasm of the nucleate "young" sieve elements contains longitudinally oriented tubules of endoplasmic reticulum. As the sieve elements develop, nuclear material is extruded into the cytoplasm by way of a fibrotubular body which is structurally distinct from the slime body. When the cells are fully expanded the slime bodies disperse. This process is followed by breakdown of a number of organelles including the nucleus and tonoplast. This apparently leaves the endoplasmic reticulum free in the cell lumen.

Leaf structure of Cananga odorata (Annonaceae) in relation to the collection of photosynthate and phloem loading: morphology and anatomy

1990 ◽  
Vol 68 (2) ◽  
pp. 354-363 ◽  
Author(s):  
David G. Fisher
Keyword(s):  
Sieve Tube ◽  
Type I ◽  
Type Ii ◽  
Tracheary Elements ◽  
Minor Vein ◽  
Type Iv ◽  
Parenchyma Cells ◽  
Vascular Parenchyma ◽  
Sieve Tubes ◽  
Cananga Odorata

Four distinct anatomical types of minor veins occur in Cananga odorata leaves. In order of decreasing size, they are (i) type I, with tracheary elements, fibers, vascular parenchyma cells, companion cells, and mostly nacreous-walled sieve-tube members; (ii) type II, with the same cell types except that the sieve-tube members have walls that usually lack nacreous thickenings; (iii) type III, with only vascular parenchyma cells and tracheids; and (iv) type IV (vein endings), with tracheary elements only. The proportions of the total minor vein length occupied by each are type I, 15.1%; type II, 27.2%; type III, 24.4%; and type IV, 33.3%. Thus about 60% of the minor vein network lacks sieve tubes. The average interveinal distance for all minor veins is 121 μm, but the average for veins containing sieve-tubes is 329 μm. Other salient features include vascular parenchyma cells up to 130 μm long, bundle-sheath cells whose lateral protuberances into the mesophyll increase extensively with decreasing vein size, and five layers of horizontally oriented spongy parenchyma cells. These features may facilitate transport of assimilate to the relatively small proportion of the minor vein network that contains sieve tubes.

Ultrastructural Changes in Leaf Tissues of Populusdeltoides spp. angulata Ait. Infected with Poplar Mosaic Virus

1972 ◽  
Vol 2 (3) ◽  
pp. 308-312 ◽  
Author(s):  
S. Navratil ◽  
M. G. Boyer
Keyword(s):  
Endoplasmic Reticulum ◽  
Mosaic Virus ◽  
Ultrastructural Changes ◽  
Cell Organelles ◽  
Sieve Elements ◽  
Virus Particles ◽  
Chloroplast Membrane ◽  
Leaf Tissues ◽  
Infected Cells

Ultrastructural observations on the foliar cells of Populusdeltoides spp. angulata Ait. infected by poplar mosaic virus revealed a high content of virus particles in the cytoplasm of most but not all young cells from chlorotic areas. Mature cells from necrotic areas contained far fewer virions while in symptomless green portions no virions were observed. Virus particles were not found in mature sieve elements or in mature nonliving xylem cells.Changes in the cytoplasm and in chloroplasts were followed. Healthy, mature chloroplasts contained well developed thylakoid systems. In infected cells, a disintegrative process at necrotization resulted in the dissolution of the thylakoid system into individual electron dense sacs which were released when the chloroplast membrane dissolved. Cytoplasmic changes were characterized by increased vacuolation. Cisternae of the endoplasmic reticulum and vesiculate bodies were also more numerous. Necrotization was accompanied by dissolution of the cell organelles.

scholarly journals Sieve Plate Pores in the Phloem and the Unknowns of Their Formation

Plants ◽  
2019 ◽  
Vol 8 (2) ◽  
pp. 25 ◽  
Author(s):  
Lothar Kalmbach ◽  
Ykä Helariutta
Keyword(s):  
Pore Formation ◽  
Current Knowledge ◽  
Sieve Tube ◽  
Model Species ◽  
Sieve Elements ◽  
Plasmodesmata Formation ◽  
Sieve Tubes ◽  
Element Evolution ◽  
Electron Microscopes ◽  
Sieve Pores

Sieve pores of the sieve plates connect neighboring sieve elements to form the conducting sieve tubes of the phloem. Sieve pores are critical for phloem function. From the 1950s onwards, when electron microscopes became increasingly available, the study of their formation had been a pillar of phloem research. More recent work on sieve elements instead has largely focused on sieve tube hydraulics, phylogeny, and eco-physiology. Additionally, advanced molecular and genetic tools available for the model species Arabidopsis thaliana helped decipher several key regulatory mechanisms of early phloem development. Yet, the downstream differentiation processes which form the conductive sieve tube are still largely unknown, and our understanding of sieve pore formation has only moderately progressed. Here, we summarize our current knowledge on sieve pore formation and present relevant recent advances in related fields such as sieve element evolution, physiology, and plasmodesmata formation.

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