Anatomical effects of 2,4-DB on tomato internodes

1981 ◽  
Vol 59 (9) ◽  
pp. 1749-1760
Author(s):  
Thompson Demetrio Pizzolato ◽  
David L. Regehr
Keyword(s):  
Secondary Wall ◽  
Sieve Tube ◽  
Tracheary Elements ◽  
Anatomical Changes ◽  
Companion Cells ◽  
Sieve Tubes ◽  
Secondary Wall Formation ◽  
Sieve Plates ◽  
Internal Phloem ◽  
Stimulation Of

Anatomical changes induced in the first internode by an aqueous spray of 4-(2,4-dichlorophenoxy)butyric acid (2,4-DB) (0.56 kg acid equivalent per hectare) confirmed the intolerance of tomato to this herbicide. Hypertrophy, hyperplasia, and plastid destruction occurred rapidly in most tissues. Many of the hyperplastic phloem cells differentiated into unusual supernumerary sieve tube members which were shorter and narrower than normal and which approximated the size of the co-differentiating companion cells. The supernumerary sieve tube members usually possessed several sieve plates and formed sieve tubes which did not follow a vertical course. Although obliteration of the supernumerary sieve tube members was stimulated, it was not associated with the formation of necrotic masses. Secondary wall formation was prevented in the protophloem fibers which became multiseptate following the stimulation of mitoses. The cambial initials were converted into a tissue of squat cells with little organization. Xylem which differentiated after treatment lost its normal heterogeneity and became a tissue of squat tracheary elements and parenchyma with scanty secondary thickening resembling wound xylem. Included phloem differentiated from parenchymatous masses within the xylem, and tylosis formation was stimulated. Pith volume increased by hypertrophy unaccompanied by hyperplasia. Although protophloem fibers did not mature in the internal phloem and limited hyperplasia and hypertrophy did occur, the internal phloem was much less affected than the external. Similarities between the anatomical effects of 2,4-DB and those reported for certain growth regulators and pathogens were noted.

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.

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.

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.

On the vascular anatomy and stomates of the lodicules of Zea mays

1980 ◽  
Vol 58 (9) ◽  
pp. 1045-1055 ◽  
Author(s):  
Thompson Demetrio Pizzolato
Keyword(s):  
Zea Mays ◽  
Zea Mays L ◽  
Vascular Anatomy ◽  
Transfer Cells ◽  
Tracheary Elements ◽  
Cell Type ◽  
Xylem Parenchyma ◽  
Abaxial Epidermis ◽  
Companion Cells ◽  
Sieve Tubes

The four lodicules of the male spikelet of Zea mays L. are supplied by one, two, or three traces. In the lower regions of the traces intermediary cells and a few phloem transfer cells occur with the companion cells and sieve tubes. Xylem transfer cells with a variety of wall thickenings intermingle in the lower regions of the traces with tracheary elements. Tracheary elements and sieve tubes in this region do not touch but are separated by the phloem and xylem parenchyma. As the lodicule trace nears the base of the lodicule, intermediary cells and transfer cells diminish. A bundle sheath surrounds the lodicule trace but does not surround the minor veins of the lodicule proper. Within the lodicule proper the trace branches prolifically, and the minor veins become peripherally placed. Most of the minor veins contain vessels and sieve tubes but a few contain sieve tubes alone. Companion cells occur in some veins but not in others. Vessels and sieve tubes frequently touch each other. Many minor veins end simultaneously in sieve elements and tracheary elements but some end in one or the other cell type. Parenchyma cells with wrinkled walls occur near the minor veins. The abaxial epidermis of the upper regions of the lodicule contains stomates.

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 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.

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.

scholarly journals Cytopathological evidence for transport of phytoplasma in infected plants

2014 ◽  
Vol 68 (4) ◽  
pp. 261-266 ◽  
Author(s):  
Anna Rudzińska-Langwald ◽  
Maria Kamińska
Keyword(s):  
Morphological Changes ◽  
Close Contact ◽  
Infected Plant ◽  
Sieve Tube ◽  
Tagetes Patula ◽  
Plant Cell Walls ◽  
Companion Cells ◽  
Phytoplasma Infection ◽  
Sieve Tubes ◽  
Helichrysum Bracteatum

Pleomorphic phytoplasmas were observed in sieve tubes, companion cells and in phloem parenchyma of <em>Tagetes patula</em> L., <em>Helichrysum bracteatum</em> Willd. and <em>Gladiolus</em> sp. L. plants with morphological changes typical for phytoplasma infection. In the pores of the sieve plate phytoplasma cells were seen which suggests that the vertical transport of this pathogen goes in the sieve tubes of infected plants throughout the sieve tube pores. The contact of the sieve tube with the neighbouring cells goes through the plasmodesmata, but no changes of the plasmodesmata were observed in the phloem of infected plants. The size and structure of unchanged plasmodesmata does not allow passing through such big structures like phytoplasma. Instead close contact between phytoplasma cells and vertical sieve tube walls takes place. Damages to the cell wall were observed forming cavities in which the phytoplasma cells were present. The damages of parenchyma and companion cells walls also were seen. In cells where the damages of the walls were observed phytoplasmas were present. The phytoplasma cells were sporadically seen also in the intercellular spaces of parenchyma. These data suggest that horizontal transport depends on damages to the infected plant cell walls caused by the phytoplasma itself.

The occurrence and structure of radial sieve tubes in the secondary xylem of Aquilaria and Gyrinops

IAWA Journal ◽  
2020 ◽  
Vol 41 (1) ◽  
pp. 109-124 ◽  
Author(s):  
Bei Luo ◽  
Tomoya Imai ◽  
Junji Sugiyama ◽  
Sri Nugroho Marsoem ◽  
Tri Mulyaningsih ◽  
...  
Keyword(s):  
Significant Role ◽  
Secondary Xylem ◽  
Sieve Tube ◽  
Lateral Wall ◽  
Direct Connection ◽  
Aquilaria Sinensis ◽  
Interxylary Phloem ◽  
Sieve Tubes ◽  
Sieve Plates ◽  
Sieve Pores

Abstract New observations of radial sieve tubes in the secondary xylem of two genera and four species of agarwood — Aquilaria sinensis, A. crasna, A. malaccensis and Gyrinops versteeghii (Thymelaeaceae) — are presented in this study. The earliest radial sieve tubes in Gyrinops are formed in the secondary xylem adjacent to the pith. The radial sieve tubes originate from the vascular cambium and develop in both uniseriate and multiseriate ray tissue. In addition to sieve plates in lateral and end walls, scattered or clustered minute sieve pores are localized in the lateral wall of radial sieve tubes. There is a direct connection between radial sieve tubes in ray tissue and axial sieve tubes in interxylary phloem strands (IP), such as (i) connection by bending of radial sieve tube strands, (ii) connection of two IP strands by an oblique bridge, and (iii) connection of two IP strands at a right angle. The average number of radial sieve tubes and interxylary phloem was found to be 1.7 per mm3 and 9.1 per mm2 in the secondary xylem. Considering the higher frequency of radial sieve tubes with the increasing thickness of the secondary xylem, the direct connections between radial and axial sieve tubes could play a significant role in assisting the translocation of metabolites in Aquilaria and Gyrinops.

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