Vascular differentiation in the wheat embryo

1971 ◽  
Vol 19 (1) ◽  
pp. 63 ◽  
Author(s):  
JG Swift ◽  
TP O'Brien
Keyword(s):  
Tracheary Element ◽  
Sieve Element ◽  
Serial Sections ◽  
Tracheary Elements ◽  
Vascular Differentiation ◽  
Tracheary Element Differentiation ◽  
Wheat Embryo ◽  
Sieve Elements ◽  
Foliage Leaf

The sequence of vascular differentiation in the scutellum, coleoptile, and firbt foliage leaf of the wheat embryo is traced by examining serial sections of these organs at selected intervals after the initial soaking of the grain. Mature sieve elements are found first in the scutellum 3-6 hr after soaking, in the midrib of the first leaf after 6 hr, and in the coleoptile after 18 hr. In all three organs xylem differentation lags behind that of the phloem; mature tracheary elements are present in the scutellum by 18 hr, in the midrib by 24 hr, and in the coleoptile by 30 hr. It is suggested that there are four loci of sieve element differentiation and two loci of tracheary element differentiation. These observations are discussed with reference to previous accounts of vascular differentiation.

A Study of the Vascular Organization of Bamboos (Poaceae-Bambuseae) Using a Microcasting Method

IAWA Journal ◽  
1998 ◽  
Vol 19 (3) ◽  
pp. 265-278 ◽  
Author(s):  
Jean-Pierre André
Keyword(s):  
Tracheary Element ◽  
Vascular Structure ◽  
Tracheary Elements ◽  
Tracheary Element Differentiation ◽  
Bamboo Nodes ◽  
Intercalary Meristem ◽  
Anatomical Finding ◽  
The Continuum

A reliable and simple microcasting method is applied to the study of the vascular structure in bamboo nodes; it provides new insights into their complexity, revealing the exact arrangement of branched vessels and clustered tracheary elements. Axial differentiation gradients in the metaxylem cell files, probable relics of the intercalary meristem, can also be found using this method. This anatomical finding can be linked to arecent hypothesis on the continuum in the tracheary element differentiation.

Vascular system of the fertile floret of Phalaris arundinacea

1989 ◽  
Vol 67 (5) ◽  
pp. 1366-1380 ◽  
Author(s):  
Thompson Demetrio Pizzolato
Keyword(s):  
Vascular System ◽  
Lower Layer ◽  
Phalaris Arundinacea ◽  
Sieve Element ◽  
Vascular Bundles ◽  
Tracheary Elements ◽  
Sieve Elements

Six vascular bundles lie in two rows of three in the rachilla at the base of the fertile floret. Each bundle relates to a lemma or palea trace. As the rachilla bundles become traces they also produce sieve elements that interconnect to form the lower layer of the sieve-element plexus. Lodicule traces join the anterior of this lower plexus. Only the tracheary elements from the rachilla bundle related to the lemma's median trace rise higher in the rachilla, and these merge into a system of anomalous tracheary elements (xylem discontinuity) that rises toward the ovule. The lower sieve-element plexus layer ascends around the xylem discontinuity into a trilobed upper plexus layer which supplies the stamen traces. A third sieve-element plexus (pistil plexus) joins the upper plexus layer by three descending prongs. The pistil plexus, which occurs at the base of the pistil, is linked on its anterior to the anterior bundle. The placental bundle rises from the posterior of the pistil plexus and furnishes the sides of the pistil with their anterolateral and posterolateral sieve elements. The posterolaterals supply the styles. The sieve elements and the xylem discontinuity of the placental bundle supply the ovule.

Vascular system of the floret of Phleum pratense

1988 ◽  
Vol 66 (9) ◽  
pp. 1818-1829 ◽  
Author(s):  
Thompson Demetrio Pizzolato
Keyword(s):  
Vascular Tissue ◽  
Vascular System ◽  
Sieve Tube ◽  
Sieve Element ◽  
Phleum Pratense ◽  
Tracheary Elements ◽  
Sieve Elements ◽  
Circular Component

Two bundles occur in the rachilla at the floret base. The anterior bundle supplies the vascular tissue for the lemma median trace, and the posterior supplies that for its two extreme laterals. The intermediate laterals of the lemma connect at the anterior bundle, and the two palea traces join near the posterior bundle to the traces for the extreme lemma laterals. Near these connections sieve elements of the two rachilla bundles link, forming the lower component of the sieve-element plexus. The xylem discontinuity begins above the anterior bundle. An upper, circular component of the sieve-element plexus surrounds the discontinuity. The sieve elements of the lodicules join the anterior of the upper plexus. The upper plexus becomes trilobed as it merges with the stamen traces. Three pistil bundles including sieve elements and tracheary elements of the xylem discontinuity join the upper plexus. These pistil bundles unite into a circular pistil plexus surrounding the discontinuity. The anterior sieve tube of the pistil joins the anterior of the pistil plexus. Sieve elements emerge from the posterolateral portions of the plexus toward the styles and leave a placental bundle of sieve elements and tracheary elements of the xylem discontinuity in the pistil posterior.

Glycerol and myo-inositol as carbon sources for the induction of xylogenesis in explants of Lactuca

1982 ◽  
Vol 60 (7) ◽  
pp. 1204-1206 ◽  
Author(s):  
L. W. Roberts ◽  
S. Baba
Keyword(s):  
Carbon Source ◽  
Lactuca Sativa ◽  
Secondary Wall ◽  
Carbon Sources ◽  
Tracheary Element ◽  
Tracheary Elements ◽  
Tracheary Element Differentiation ◽  
Cultural Conditions ◽  
Exogenous Carbon Source

Glycerol (2% w/v) and myo-inositol (2% w/v), respectively, functioned as the principal exogenous carbon source for the induction of tracheary element differentiation in cultured expiants of lettuce pith (Lactuca sativa cv. Romána). Although tracheary elements were first observed after 3 days on a xylogenic medium supplemented with either glucose (2% w/v) or myo-inositol (2% w/v), the induction of xylogenesis in explants cultured on a similar medium containing glycerol (2% w/v) required a minimum of 6 days. Tracheary elements formed in the presence of glycerol and myo-inositol, respectively, were characterized by various patterns of scalariform-reticulate secondary wall thickenings which were indistinguishable from tracheary elements produced under similar cultural conditions in the presence of glucose as the principal carbon source. This is the first report of a major exogenous carbon source other than a carbohydrate supporting the cytodifferentiation of tracheary elements under in vitro conditions.

Structural aspects of tracheary element differentiation in suspension cultures of Zinnia elegans

1989 ◽  
Vol 47 ◽  
pp. 768-769
Author(s):  
C. H. Haigler ◽  
A. W. Roberts
Keyword(s):  
Tracheary Element ◽  
Vesicle Fusion ◽  
Zinnia Elegans ◽  
Cellulose Synthesis ◽  
Tracheary Elements ◽  
Animal Cells ◽  
Mesophyll Cells ◽  
Fixation Techniques ◽  
Localized Patterns ◽  
Structural Aspects

Tracheary elements, the water-conducting cells in plants, are characterized by their reinforced walls that became thickened in localized patterns during differentiation (Fig. 1). The synthesis of this localized wall involves abundant secretion of Golgi vesicles that export preformed matrix polysaccharides and putative proteins involved in cellulose synthesis. Since the cells are not growing, some kind of endocytotic process must also occur. Many researchers have commented on where exocytosis occurs in relation to the thickenings (for example, see), but they based their interpretations on chemical fixation techniques that are not likely to provide reliable information about rapid processes such as vesicle fusion. We have used rapid freezing to more accurately assess patterns of vesicle fusion in tracheary elements. We have also determined the localization of calcium, which is known to regulate vesicle fusion in plant and animal cells.Mesophyll cells were obtained from immature first leaves of Zinnia elegans var. Envy (Park Seed Co., Greenwood, S.C.) and cultured as described previously with the following exceptions: (a) concentration of benzylaminopurine in the culture medium was reduced to 0.2 mg/l and myoinositol was eliminated; and (b) 1.75ml cultures were incubated in 22 x 90mm shell vials with 112rpm rotary shaking. Cells that were actively involved in differentiation were harvested and frozen in solidifying Freon as described previously. Fractures occurred preferentially at the cell/planchet interface, which allowed us to find some excellently-preserved cells in the replicas. Other differentiating cells were incubated for 20-30 min in 10(μM CTC (Sigma), an antibiotic that fluoresces in the presence of membrane-sequestered calcium. They were observed in an Olympus BH-2 microscope equipped for epi-fluorescence (violet filter package and additional Zeiss KP560 barrier filter to block chlorophyll autofluorescence).

scholarly journals A crystalline inclusion in sieve element nuclei of Amsinckia. II. The inclusion in maturing cells

1979 ◽  
Vol 38 (1) ◽  
pp. 11-22
Author(s):  
K. Esau ◽  
A.C. Magyarosy
Keyword(s):  
Hydrostatic Pressure ◽  
Sieve Element ◽  
Crystalline Inclusion ◽  
Sieve Elements ◽  
P Protein ◽  
Sudden Release ◽  
Sieve Plates ◽  
Tubular Components

The compounds crystalloids formed in sieve element nuclei of Amsinckia douglasiana A. DC. (Boraginaceae) during differentiation of the cell become disaggregated during the nuclear breakdown characteristic of a maturing sieve element. The phenomenon occurs in both healthy and virus-infected plants. The crystalloid component termed cy, which is loosely aggregated, separates from the densely aggregated component termed cx and disperses. The cx component may become fragmented, or broken into large pieces, or remain intact after the cell matures. After their release from the nucleus both crystalloid components become spatially associated with the dispersed P-protein originating in the cytoplasm, but remain distinguishable from it. The component tubules of P-protein are hexagonal in transections and are somewhat wider than the 6-sided cy tubules. The cx tubules are much narrower than the P-protein or the cy tubules and have square transections. Both the P-protein and the products of disintegrated crystalloids accumulate at sieve plates in sieve elements subjected to sudden release of hydrostatic pressure by cutting the phloem. The question of categorizing the tubular components of the nuclear crystalloid of a sieve element with reference to the concept of P-protein is discussed.

Comparison between tracheary element lignin formation and extracellular lignin-like substance formation during the culture of isolated Zinnia elegans mesophyll cells

Biologia ◽  
2011 ◽  
Vol 66 (1) ◽  
Author(s):  
Yasushi Sato ◽  
Youko Yajima ◽  
Naohito Tokunaga ◽  
Ross Whetten
Keyword(s):  
Peroxidase Activity ◽  
Cell Walls ◽  
Vascular Plants ◽  
Culture Media ◽  
Tracheary Element ◽  
Zinnia Elegans ◽  
Tracheary Elements ◽  
Mesophyll Cells ◽  
Isolated Mesophyll Cells ◽  
Lignin Deposition

AbstractLignin is synthesized not only during morphogenesis of vascular plants but also in response to various stresses. Isolated Zinnia elegans mesophyll cells can differentiate into tracheary elements (TEs), and deposit lignin into cell walls in TE-inductive medium (D medium). Meanwhile isolated mesophyll cells cultured in hormone-free medium (Co medium) accumulate stress lignin-like substance during culture. Therefore this culture system is suitable for study of lignin and lignin-like substance formation.In D medium lignin was deposited in TEs, but in Co medium, extracellular lignin-like substance accumulated. Analysis of the culture media indicated the presence of dilignols in D culture, but not in Co culture. To investigate the fate of lignin precursors, we added coniferyl alcohol (CA) in each culture. In Co medium, CA was polymerized into dilignols rapidly but they were present only temporarily, and in D medium CA was polymerized into dilignols relatively slowly but their content increased continually.Meanwhile, in Co culture, peroxidase activity in the medium was much higher than the peroxidase activity bound ionically to the cell walls. In D culture, ionically bound peroxidase activity was higher than that in the medium. These results may suggest that lignin deposition in TEs is related to ionically bound peroxidases in D culture, and lignin-like substance deposition in the medium is related to peroxidases in the medium in Co culture.

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