Inclusions in nuclei and plastids of Boraginaceae and their possible taxonomic significance

1989 ◽  
Vol 67 (12) ◽  
pp. 3608-3617 ◽  
Author(s):  
Deborah D. Fisher ◽  
Jennifer Thorsch ◽  
Katherine Esau
Keyword(s):  
Proteolytic Enzyme ◽  
Ultrastructural Level ◽  
Sieve Element ◽  
Nuclear Inclusions ◽  
Sieve Elements ◽  
Phloem Parenchyma ◽  
The Family ◽  
Parenchyma Cells ◽  
Parallel Arrangement ◽  
Systematic Character

A survey of 68 species representing 28 genera in the family Boraginaceae was conducted at the ultrastructural level to determine presence of nuclear crystalloids in sieve elements and occurrence of crystalline structures in chloroplasts of phloem parenchyma cells. Nuclear crystalloids were identified in 55 of the species examined, and 25 of the species contained chloroplast crystals. The nuclear crystals were mainly composed of thin rods densely packed in parallel arrangement. Their sizes, shapes, and numbers varied, but they were basically prismatic or possibly cubical. During maturation, the sieve element nuclei disintegrated and the crystalloids were released into the cell lumen where they remained intact. Loosely arranged paracrystalline components associated with the dense nuclear crystalloids were found only in the genus Amsinckia. Crystalline inclusions in the parenchyma chloroplasts were made up of fibers loosely aligned in a herringbone pattern. The lability of the chloroplast crystals to the proteolytic enzyme, protease, was tested on 10 species, and only Onosma stellulatum Waldst. & Kit. chloroplast crystals were routinely digested. The high percentage of nuclear crystalloids found in this family suggests that these inclusions could be valuable as a systematic character. Key words: sieve elements, nuclear inclusions, plastid crystals, Boraginaceae.

Fine structure of the phloem of Pisum sativum. II. The companion cell and phloem parenchyma

1965 ◽  
Vol 13 (2) ◽  
pp. 185
Author(s):  
MC Wark
Keyword(s):  
Fine Structure ◽  
Sieve Element ◽  
Companion Cell ◽  
Secondary Phloem ◽  
Sieve Elements ◽  
Phloem Parenchyma ◽  
Wall Structures ◽  
Companion Cells ◽  
Parenchyma Cells ◽  
Vacuolated Cells

The companion cells of the secondary phloem of Pisum contain all the organelles characteristic of cells possessing an active metabolism. The cytoplasm of the companion cells shows little change during ontogeny. Complex plasmodesmata connect the sieve elements and companion cells. These are the only connections observed between the sieve elements and other phloem cells. New wall structures of the companion cells are described. These structures are here tentatively called trabeculae; they intrude into the cytoplasm, but never completely cross the cell. The trabeculae alter in appearance at the time when the sieve element nucleus and tonoplast disappear. The phloem parenchyma cells are large vacuolated cells wider in diameter but shorter in length than the sieve elements. They contain all the organelles found in normal photosynthetic tissue. The cytoplasm of the phloem parenchyma shows little change during ontogeny. Plasmodesmata of well-developed pit fields connect the phloem parenchyma with the companion cells. The phloem parenchyma does not communicate with the sieve elements.

Anatomy of the Secondary Phloem in Winteraceae

IAWA Journal ◽  
1984 ◽  
Vol 5 (1) ◽  
pp. 13-43 ◽  
Author(s):  
Katherine Esau ◽  
Vernon I. Cheadle
Keyword(s):  
Protein Body ◽  
Sieve Element ◽  
Secondary Phloem ◽  
Phloem Parenchyma ◽  
The Family ◽  
Companion Cells ◽  
Parenchyma Cells ◽  
Evolutionary Level ◽  
Fusiform Initials ◽  
Sieve Plates

The secondary phloem of nine species in five genera of Winteraceae was examined with regard to features that could serve for taxonomic and phylogenetic evaluation of the family. The species examined were as follows: Bubbia pauciflora, B. semecarpoides, Drimys lanceolata, D. winteri, Exospermum stipitatum, Pseudo wintera axillaris, Zygogynum baillonii, Z. bicolor, and Z. vinkii. The nine species showed the following common characteristics: 1) origin from nonstoried vascular cambium with long fusiform initials; 2) ray system consisting of high multiseriate and high uniseriate rays; 3) occurrence of secondary partitioning in the differentiating phloem so that the sieve elements are much shorter than the tracheids; 4) lack of sharp differentiation between lateral sieve areas and those of the sieve plates; 5) predominance of compound sieve plates; 6) short companion cells, often single in a given sieve element; 7) phloem parenchyma cells in strands; 8) lack of specialised fibres (bast fibres) in the secondary phloem; 9) presence of nondispersing protein body in the sieve element protoplast. Features numbered 1, 2, 4-6 are considered to be indications of low evolutionary level. The significance of the other three features (3, 7-9) requires further evaluation. Among these three is the secondary partitioning the occurrence of which seems to imply that in some taxa the well known sequence of evolutionary shortening of cambial initials and their derivatives may be accelerated on the phloem side.

Fine structure of the primary root phloem of Pisum

1968 ◽  
Vol 16 (1) ◽  
pp. 37 ◽  
Author(s):  
SY Zee ◽  
TC Chambers
Keyword(s):  
Primary Root ◽  
Root Apex ◽  
Sieve Element ◽  
Cross Wall ◽  
Secondary Phloem ◽  
Sieve Elements ◽  
Phloem Parenchyma ◽  
Pisum Sativum L ◽  
Companion Cells ◽  
Stem Internode

The morphogenesis of the sieve elements, companion cells, and phloem parenchyma in the region between 0.5 and 2.0 mm from the actively growing root apex of seedlings of Pisum sativum L. cv. Telephone is described. The overall developmental pattern is essentially similar to that already described for the secondary phloem of the young stem internode of the same species, although differences in the development of some organelles do exist between the two types of phloem. The development of the sieve element is traced from the earliest stages of cross wall formation up to the morphologically mature stages. Very few sieve elements reach morphological maturity in this region. The possibility that the functional translocatory sieve elements are those at earlier stages of development is discussed.

Sugar beet petiole structure: vascular anastomoses and phloem ultrastructure

1985 ◽  
Vol 63 (12) ◽  
pp. 2295-2304 ◽  
Author(s):  
John W. Oross ◽  
William J. Lucas
Keyword(s):  
Endoplasmic Reticulum ◽  
Sugar Beet ◽  
Vascular Anatomy ◽  
Initial Contact ◽  
Lateral Movement ◽  
Sieve Elements ◽  
Phloem Parenchyma ◽  
Microfilament Bundles ◽  
Companion Cells ◽  
Parenchyma Cells

The vascular anatomy and phloem ultrastructure of the sugar beet petiole were studied in an attempt to evaluate the potential of petiolar phloem anastomoses to accommodate lateral movement of translocates across this structure. Clearings revealed that six of the eight interveinal regions between the nine major, axially oriented veins were connected by many anastomoses. The two interveinal areas characterized by the fewest anastomoses were located near the margin of the petiole. It was concluded that lateral translocation via anastomoses would be most efficient in the central part of the petiole. A light microscope study of the structure of the junction between anastomosing and continuous veins revealed that the sieve elements of each of the merging veins were separated from each other, for distances of up to 6 mm beyond the point of initial contact, by phloem parenchyma cells. The presence of phloem parenchyma cells in this position, and between the clusters of sieve elements that occur across the phloem of the large bundles, was taken as an indication that the parenchyma cells may have an important role in lateral translocation. An ultrastructural study of the petiolar phloem revealed that the phloem parenchyma and companion cells could be easily distinguished on the basis of the structure of the chloroplasts, dictyosomes, and endoplasmic reticulum. Microfilament bundles and spine-coated tubules and (or) vesicles were uniquely present in the parenchyma cells. The ultrastructure of the phloem parenchyma cells is discussed relative to their possible role in mediating the movement of sugars through the anastomoses.

scholarly journals Effects of Root Restriction on Ultrastructure of Phloem Tissues in Grape Berry

HortScience ◽  
2009 ◽  
Vol 44 (5) ◽  
pp. 1334-1339 ◽  
Author(s):  
ZhaoSen Xie ◽  
Charles F. Forney ◽  
WenPing Xu ◽  
ShiPing Wang
Keyword(s):  
Growth Phase ◽  
Rapid Growth ◽  
Developmental Process ◽  
Grape Berry ◽  
Control Treatment ◽  
Sieve Elements ◽  
Phloem Parenchyma ◽  
Parenchyma Cells ◽  
Variation Explained ◽  
Root Restriction

In this study, the ultrastructure of phloem and its surrounding parenchyma cells in the developing grape berry produced under root restriction or without (control) was for the first time systematically investigated through transmission electron microscopy during the entire developmental process of the berry. The results showed that root restriction increased the number of plasmodesmata between sieve elements (SE) and companion cells (CC) and between the SE/CC complex and phloem parenchyma cells. Sieve elements in fruit produced under root restriction were smaller in size than those from the control treatment, but CC were bigger than in the control treatment. During the first rapid growth phase of the grape berry, there was denser cytoplasm in the CC produced under root restriction having more abundant mitochondria, endoplasmic reticulum, multivesicular bodies, vesicles, and plastids than in control fruit. During the second rapid growth phase of the grape berry, CC under root restriction showed more serious plasmolysis. Cytoplasmic contents such as vesicles were fused into the vacuole of which the tonoplast nearly disappeared in the phloem parenchyma cells, and cytoplasmic contents in fruit cells produced under root restriction became denser than the control treatment. These results demonstrated that grape berry adapted to the root restriction stress through ultrastructure variation of the phloem, and this variation explained the increase of photosynthate accumulation in the grape berry observed under root restriction.

Nuclear Crystalloids in Sieve Elements of Species of Echium (Boraginaceae)

1982 ◽  
Vol 54 (1) ◽  
pp. 149-160
Author(s):  
KATHERINE ESAU ◽  
JENNIFER THORSCH
Keyword(s):  
Protein A ◽  
Sieve Element ◽  
Crystalline Form ◽  
Two Dimensional ◽  
Common Component ◽  
Dimensional Lattice ◽  
Sieve Elements ◽  
Ultrastructural Studies ◽  
P Protein ◽  
Systematic Character

Ultrastructural studies of differentiating phloem of the midvein in 15 species of Echium (Boraginaceae) have shown that in every species one or more crystalloids develop in sieve-element nuclei. These inclusions appear as soon as the cell begins to differentiate from a procambial derivative. Small at first, they enlarge later, particularly in length. The crystalloid may extend end-to-end in the correspondingly elongated nucleus. When the nucleus disintegrates in the maturing cell the crystalloid is released into the cell lumen where it remains intact or becomes fractured into large pieces. No dissociation into subunits was observed. The crystalloids are composed of tightly packed narrow rods (tubules) forming a two-dimensional lattice of squares in transections and a system of parallel striations in longitudinal sections. The similarities of these inclusions to the crystalline form of P-protein in Fabaceae raises the question of terminological delimitation of P-protein, a common component of angiospermous sieve-element protoplasts. The occurrence of nuclear crystalloids in another previously investigated genus in the Boraginaceae, Amsinckia, suggests that this inclusion should be explored in boraginaceous representatives for its possible value as a systematic character.

Nuclear crystalloids in sieve elements of Boraginaceae: a protein digestion study

1983 ◽  
Vol 64 (1) ◽  
pp. 37-47
Author(s):  
J. Thorsch ◽  
K. Esau
Keyword(s):  
Proteolytic Enzymes ◽  
Differential Response ◽  
Sieve Element ◽  
Enzyme Digestion ◽  
The Other ◽  
Sieve Plate ◽  
Protein Digestion ◽  
Sieve Elements ◽  
P Protein ◽  
Parallel Arrangement

Nuclear crystalloids have been found in sieve elements of several Boraginaceae. Nuclei of differentiating sieve elements of Echium and other genera except Amsinckia contain one or more crystalloids composed of thin rods densely packed in parallel arrangement. After the nuclei disintegrate in the maturing sieve element the crystalloids are released into the cell lumen where they persist intact. In Amsinckia the crystalloid consists of two components: a dense component, similar to the crystalloid in the other genera and a loosely arranged paracrystalline component. The proteinaceous nature of the nuclear crystalloids and their possible similarity to P-protein was investigated by enzyme digestion techniques. Three proteolytic enzymes were employed in this study: protease, pepsin and trypsin. Successful digestion of the dense crystalloid in both Echium and Amsinckia was obtained with each enzyme tested. P-protein plugging the sieve plate pores was also digested. The loose component in Amsinckia and the aggregated and dispersed P-protein were not affected by the enzyme digestion procedures. These results seemed to indicate that the density or compactness of the proteinaceous inclusions may play a role in the differential response.

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.

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