Studies on the Phloem Sealing Mechanism in Ricinus Fruit Stalks

1983 ◽  
Vol 10 (6) ◽  
pp. 561 ◽  
Author(s):  
J Kallarackal ◽  
JA Milburn
Keyword(s):  
Electron Microscopy ◽  
Sieve Tube ◽  
Sieve Plate ◽  
Tube System ◽  
Phloem Sap ◽  
Starch Grains ◽  
P Protein ◽  
Sieve Tubes ◽  
Sealing Mechanism ◽  
Sieve Plates

Fruit stalks of R. communis were made to exude phloem sap by repeated slicing at intervals of a few minutes. Samples 1 mm thick from the fruit stalks were fixed for electron microscopy. Samples were also fixed and processed for electron microscopy from previously intact (non-exuding) fruit stalks. Examination of the sieve tubes from these two different samples showed predominantly open sieve-plate pores in the exuding fruit stalk. The sieve plates of the non-exuding fruit stalk showed occlusion of the sieve-plate pores by P-protein. The starch grains from the broken plastids also had characteristic distributions. The implications of these observations are discussed in relation to comprehending the mechanism by which sieve-plate pores become choked, and so sealing the sieve-tube system as a result of injury.

Studies on the Feeding and Nutrition of Tuberolachnus Salignus (Gmelin) (Homoptera, Aphididae):

1957 ◽  
Vol 34 (3) ◽  
pp. 334-341
Author(s):  
T. E. MITTLER
Keyword(s):  
Host Plant ◽  
Sieve Tube ◽  
Normal Rate ◽  
Phloem Sap ◽  
Food Canal ◽  
Tuberolachnus Salignus ◽  
Normal Feeding ◽  
Sieve Tubes ◽  
Considerable Pressure ◽  
Salix Spp

1. A study has been made of the factors involved in the uptake of phloem sap by Tuberolachnus salignus (Gmelin) feeding on the stems of various Salix spp. 2. A method has been developed for maintaining the parthenogenetic viviparous forms of T. salignus in culture throughout the year. 3. It has been established that during normal feeding T. salignus have the tips of their stylets inserted into the phloem sieve-tubes of the host plant. 4. The phloem sieve-tube sap of intact and turgid willow stems is under considerable pressure. This pressure forces the sieve-tube mp up the stylet food canal of feeding aphids, and also causes the sieve-tube sap to exude for many hours from the cut end of embedded stylet bundles. 5. Intact and feeding T. salignus rely almost entirely on this pressure to maintain their normal rate of eieve-tube sap uptake. The aphids must, however, swallow actively in order to ingest.

Slime plugs do not inhibit surge flow in sieve tubes

1982 ◽  
Vol 60 (7) ◽  
pp. 1281-1284 ◽  
Author(s):  
Gregor F. Barclay
Keyword(s):  
P Protein ◽  
Heracleum Mantegazzianum ◽  
Sieve Tubes ◽  
Heracleum Sphondylium ◽  
Sieve Plates

Slime plugs, composed largely of P protein, on sieve plates in phloem of Heracleum mantegazzianum L. and Heracleum sphondylium Somm. and Lev. do not seem to be effective in preventing surge flow caused by loss of turgor, therefore calling into question the role of slime plugs in phloem.

scholarly journals THE FINE STRUCTURE OF DIFFERENTIATING SIEVE TUBE ELEMENTS

1965 ◽  
Vol 25 (1) ◽  
pp. 79-95 ◽  
Author(s):  
G. Benjamin Bouck ◽  
James Cronshaw
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Fibrous Material ◽  
Sieve Tube ◽  
Longitudinal Direction ◽  
Sieve Plate ◽  
Wall Surface ◽  
Developmental Sequences ◽  
Tubular Form

The developmental sequences leading to the formation of mature sieve tube elements were studied in pea plants by electron microscopy. From this study it has been found that the peripheral layer of cytoplasm in the mature element is composed of flattened cisternae which are apparently derived from a tubular form of endoplasmic reticulum (ER) and possibly the nuclear envelope. These flattened cisternae, designated in this report as sieve tube reticula, are attached perpendicularly to the wall surface and are oriented in a predominantly longitudinal direction. Cisternae of the sieve tube reticulum are frequently associated with the slime in mature elements, and tubular ER may be associated with slimelike material in the developing sieve tube element. During differentiation mitochondria become reduced in size and chloroplasts either fail to develop stroma and grana lamellae or lose them early in development. In agreement with other workers it is found that the sieve plate pores appear to be plugged with a finely fibrous material, presumably "slime." Nacreous wall formation is well established before reorganization of cytoplasmic components. Microtubules are prevalent during these early stages, but are lost as the element matures.

Seasonal Changes in Callose Levels and Fluorescein Translocation in the Phloem of Vitis Vinifera L.

IAWA Journal ◽  
1991 ◽  
Vol 12 (3) ◽  
pp. 223-234 ◽  
Author(s):  
Roni Aloni ◽  
Carol A. Peterson
Keyword(s):  
Vitis Vinifera ◽  
Sieve Tube ◽  
Growing Season ◽  
Early Spring ◽  
Vitis Vinifera L ◽  
First Year ◽  
Secondary Phloem ◽  
Radial Gradient ◽  
Sieve Tubes ◽  
Sieve Plates

The secondary phloem of Vitis vinifera L. is characterised by a radial gradient of sieve tube diameters. Sieve tubes maturing early in the growing season have the largest diameters; those maturing late in the season have the smallest. In early spring, masses of winter dormancy callose are gradually digested in a polar radial pattern, proceeding outwards from the cambium. The fluorescent dye, fluorescein, was used to detect translocation in sieve tubes. During spring, dye translocation was first observed in the wider sieve tubes produced near the end of the previous year and wh ich had reduced amounts of callose. But translocation was not observed in the very narrow sieve tubes formed at the end of the year although they were the first to be callose free. The reactivated sieve tubes functioned for about one month. New sieve tubes differentiated three weeks after dormancy callose breakdown and started to function about one week later, so that the transition of translocation activity from the sieve tubes of the previous year to those of the current year is relatively rapid. The sieve tubes formed toward the end of the growing season (but not the narrowest ones formed at the very end of the season) function during parts of two successive seasons, while the sieve tubes forrned early in the season usually function during the first year only. Callose amounts increase gradually during summer in both the old and new sieve tubes and become relatively heavy in the old ones. At this developmental stage, translocation occurs through young sieve plates with relatively high callose deposits.

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.

Comparative Bark Anatomy of Root and Stem in Styrax Camporum (Styracaceae)

IAWA Journal ◽  
2005 ◽  
Vol 26 (4) ◽  
pp. 477-487 ◽  
Author(s):  
Silvia Rodrigues Machado ◽  
Carmen Regina Marcati ◽  
Berta Lange de Morretes ◽  
Veronica Angyalossy
Keyword(s):  
Phenolic Compounds ◽  
Stem Bark ◽  
Secondary Phloem ◽  
Starch Grains ◽  
Sieve Tubes ◽  
Sieve Plates ◽  
Bark Anatomy

The bark of Styrax camporum Pohl (Styracaceae) differs anatomically in the root and stem. Roots have layered secondary phloem; short sieve tubes with simple, transverse or more or less inclined sieve plates; fibres in tangential bands; astrosclereids; wide rays, and a poorly developed periderm. Stems have non-layered secondary phloem; longer sieve tubes with compound, scalariform, inclined sieve plates; sclerified cells and brachysclereids; a developed periderm, and a non-persistent rhytidome. Prismatic crystals, starch grains, phenolic compounds and lipidic contents were observed in root and stem bark cells. The differences between the secondary phloem of root and stem are discussed.

Sieve tube elements in the stem of Neptunia oleracea Lour

1968 ◽  
Vol 16 (3) ◽  
pp. 433 ◽  
Author(s):  
JJ Shah ◽  
MR James
Keyword(s):  
Aquatic Plant ◽  
Sieve Tube ◽  
Sieve Plate ◽  
Callose Deposition ◽  
Nuclear Disintegration ◽  
Full Development ◽  
Companion Cells ◽  
Sieve Plates ◽  
Structural Aspects ◽  
Sieve Tube Element

Some structural aspects of the phloem of Neptunia oleracea, an aquatic plant, are reported. The sieve tube elements on an average are 190μ long and 13μ wide and have compound sieve plates at varying degrees of inclination. The developing sieve tube element has a single large spindle-shaped slime body, which presumably has an outer membrane. The slime body undergoes dispersal before or after full development of the sieve plate, but often nuclear degeneration occurs first. Distinct slime plugs are absent. Plastids and other granular bodies are attached to many of the strands, which are less than 0.5μ in diameter. During the process of nuclear disintegration the nuclear membrane is indistinct, and extruded nucleolus is not observed. Sieve areas and connections are comparatively few in number, and the sieve areas and wall connections as well as the sieve plates show scanty callose deposition. Plastids are abundant in the sieve tube elements, especially near the sieve plates. The companion cells of two consecutive sieve tube elements are placed on alternate sides and hence their longitudinal continuity is not always maintained. Companion cells do not exceed the length of the sieve tube element.

scholarly journals Phytoplasma-Triggered Ca2+ Influx Is Involved in Sieve-Tube Blockage

2013 ◽  
Vol 26 (4) ◽  
pp. 379-386 ◽  
Author(s):  
Rita Musetti ◽  
Stefanie V. Buxa ◽  
Federica De Marco ◽  
Alberto Loschi ◽  
Rachele Polizzotto ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Host Plants ◽  
Sieve Tube ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Wall Thickening ◽  
Sieve Plate ◽  
Callose Deposition ◽  
Phytoplasma Infection ◽  
Sieve Tubes

Phytoplasmas are obligate, phloem-restricted phytopathogens that are disseminated by phloem-sap-sucking insects. Phytoplasma infection severely impairs assimilate translocation in host plants and might be responsible for massive changes in phloem physiology. Methods to study phytoplasma- induced changes thus far provoked massive, native occlusion artifacts in sieve tubes. Hence, phytoplasma-phloem relationships were investigated here in intact Vicia faba host plants using a set of vital fluorescent probes and confocal laser-scanning microscopy. We focused on the effects of phytoplasma infection on phloem mass-flow performance and evaluated whether phytoplasmas induce sieve-plate occlusion. Apparently, phytoplasma infection brings about Ca2+ influx into sieve tubes, leading to sieve-plate occlusion by callose deposition or protein plugging. In addition, Ca2+ influx may confer cell wall thickening of conducting elements. In conclusion, phytoplasma effectors may cause gating of sieve-element Ca2+ channels leading to sieve-tube occlusion with presumptive dramatic effects on phytoplasma spread and photoassimilate distribution.

Lateral sieve-area pores in woody dicotyledons

1971 ◽  
Vol 49 (8) ◽  
pp. 1509-1515 ◽  
Author(s):  
R. F. Evert ◽  
B. P. Deshpande ◽  
S. E. Eichhorn
Keyword(s):  
Electron Microscopy ◽  
Osmium Tetroxide ◽  
Populus Deltoides ◽  
Robinia Pseudoacacia ◽  
Quercus Alba ◽  
Secondary Phloem ◽  
Salix Nigra ◽  
Ulmus Americana ◽  
P Protein ◽  
Sieve Plates

The secondary phloem of seven species of woody dicotyledons (Populus deltoides, Quercus alba, Rhus glabra, Robinia pseudoacacia, Salix nigra, Tilia americana, and Ulmus americana) was fixed in glutaraldehyde and in formaldehyde–glutaraldehyde and postfixed in osmium tetroxide for electron microscopy. The pores of the lateral sieve areas are essentially similar in structure to those of the sieve plates, with the exception that many of the lateral sieve-area pores contain median nodules at maturity. In addition, some pore groups in Rhus, Robinia, and Tilia are associated with median cavities, median enlargements arising through the union of two or more median nodules, similar to those associated with the sieve areas of conifers. The lateral sieve-area pores are lined by the plasmalemma and variable amounts of callose and contain P-protein. It has been concluded that the P-protein normally is loosely arranged in the pores.

scholarly journals Non-dispersive phloem-protein bodies (NPBs) of Populus trichocarpa consist of a SEOR protein and do not respond to cell wounding and Ca2+

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e4665 ◽  
Author(s):  
Daniel L. Mullendore ◽  
Timothy Ross-Elliott ◽  
Yan Liu ◽  
Hanjo H. Hellmann ◽  
Eric H. Roalson ◽  
...  
Keyword(s):  
Populus Trichocarpa ◽  
Sieve Tube ◽  
Sieve Element ◽  
Protein Bodies ◽  
Genome Database ◽  
P Protein ◽  
Wound Responses ◽  
Specific Proteins ◽  
Sieve Tubes ◽  
P Proteins

Differentiating sieve elements in the phloem of angiosperms produce abundant phloem-specific proteins before their protein synthesis machinery is degraded. These P-proteins initially form dense bodies, which disperse into individual filaments when the sieve element matures. In some cases, however, the dense protein agglomerations remain intact and are visible in functional sieve tubes as non-dispersive P-protein bodies, or NPBs. Species exhibiting NPBs are distributed across the entire angiosperm clade. We found that NPBs in the model tree, Populus trichocarpa, resemble the protein bodies described from other species of the order Malpighiales as they all consist of coaligned tubular fibrils bundled in hexagonal symmetry. NPBs of all Malpighiales tested proved unresponsive to sieve tube wounding and Ca2+. The P. trichocarpa NPBs consisted of a protein encoded by a gene that in the genome database of this species had been annotated as a homolog of SEOR1 (sieve element occlusion-related 1) in Arabidopsis. Sequencing of the gene in our plants corroborated this interpretation, and we named the gene PtSEOR1. Previously characterized SEOR proteins form irregular masses of P-protein slime in functional sieve tubes. We conclude that a subgroup of these proteins is involved in the formation of NPBs at least in the Malpighiales, and that these protein bodies have no role in rapid wound responses of the sieve tube network.

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