DEVELOPMENTAL STUDIES OF ELODEA CANADENSIS MICHX.: I. MORPHOLOGICAL DEVELOPMENT AT THE SHOOT APEX

1957 ◽  
Vol 35 (1) ◽  
pp. 13-24 ◽  
Author(s):  
Hugh M. Dale
Keyword(s):  
Shoot Apex ◽  
Cell Walls ◽  
Superficial Layer ◽  
Leaf Primordia ◽  
Morphological Development ◽  
Developmental Studies ◽  
Adaxial Surface ◽  
Intercalary Meristem ◽  
Leaf Whorl ◽  
Leaf Insertion

The shoot apex consists of a few initial cells at the tip of a thimble devoid of leaf initials for at least 100 μ. Leaf primorida are initiated from the superficial layer of cells, whereas branch buds arising among the; very youngest leaf primordia are produced deeper in the apex. Chinks occur where three or more cell walls come together. The tissue of the stem for the first 200 μ has no internodes. Two squamulae intervaginales lie on the adaxial surface of each leaf with which their development is associated. Internodes are initiated by the longitudinal growth and division of cells from the bottom of the leaf insertion disks. Cells of the young node divide longitudinally to increase the diameter of the nodal disk and to split the intercalary meristem into segments. Internodes are thus initiated with lacunae. Cells destined to become wood vacuolate at the seventh leaf whorl. Scalariform thickenings are produced but quickly disintegrate along with the rest of the xylem cells leaving a lacuna in the center of the stem. The bast surrounding the central xylem differentiates only slightly, beginning at the 20th leaf whorl, whereas the leaf traces and vertical cortical strands are apparent in younger tissue.

Periclinal and oblique divisions in the surface layer of the shoot apex of tomato (Lycopersicon esculentum)

1985 ◽  
Vol 63 (9) ◽  
pp. 1564-1566 ◽  
Author(s):  
V. K. Sawhney ◽  
K. N. Chandra Sekhar
Keyword(s):  
Surface Layer ◽  
Lycopersicon Esculentum ◽  
Shoot Apex ◽  
Cell Walls ◽  
Leaf Primordia ◽  
Young Leaf ◽  
Shoot Meristem ◽  
Outermost Layer ◽  
Lycopersicon Esculentum Mill ◽  
Mitotic Figures

The occurrence of periclinal and obliquely oriented planes of mitotic figures and cell walls in the outermost layer of the tomato (Lycopersicon esculentum Mill.) shoot meristem is reported. The frequency of such divisions was low, but periclinally and obliquely oriented walls were distributed throughout the surface layer of the meristem and the young leaf primordia.

Qualitative histochemistry of the shoot apex of Triticum

1972 ◽  
Vol 50 (1) ◽  
pp. 241-244 ◽  
Author(s):  
Lance S. Evans ◽  
Arthur R. Berg
Keyword(s):  
Triticum Aestivum ◽  
Acid Phosphatase ◽  
Succinate Dehydrogenase ◽  
Dehydrogenase Activity ◽  
Shoot Apex ◽  
Cell Walls ◽  
Histochemical Staining ◽  
Leaf Primordia ◽  
Succinate Dehydrogenase Activity ◽  
Apical Base

Qualitative histochemical assays localized lipids, carbohydrates, succinate dehydrogenase, and acid phosphatase in Triticum aestivum seedlings. Starch was present in the base of the shoot apex and near vascular tissues throughout the seedlings. Succinate dehydrogenase activity was located in the apical summit, apical base, young leaf primordia, and very young axillary buds. Acid phosphatase was localized at the base of the apex, scutellum, and aleurone tissues. Thicker cell walls were noted in the epidermis of the apical dome and at the base of the apex. This combination of histochemical staining patterns suggests initiation of provascular tissue very early in leaf initiation.

Root hair deformation in the infection process of Alnus rubra

1983 ◽  
Vol 61 (11) ◽  
pp. 2863-2876 ◽  
Author(s):  
Alison M. Berry ◽  
John G. Torrey
Keyword(s):  
Root Hair ◽  
Cell Walls ◽  
Root Hairs ◽  
Infection Process ◽  
Alnus Rubra ◽  
Pseudomonas Cepacia ◽  
Developmental Studies ◽  
Experimental Conditions ◽  
Root Hair Cell ◽  
Root Hair Deformation

Structural and cell developmental studies of root hair deformation in Alnus rubra Bong. (Betulaceae) were carried out following inoculation with the soil pseudomonad Pseudomonas cepacia 85, alone or in concert with Frankia, and using axenically grown seedlings. Deformational changes can be observed in elongating root hairs within 2 h of inoculation with P. cepacia 85. These growing root hairs become branched or multilobed and highly modified from the single-tip growth of axenic root hairs. The cell walls of deformed hairs are histologically distinctive when stained with the fluorochrome acridine orange. Filtrate studies using P. cepacia 85 suggest that the deforming substance is not a low molecular weight compound. Root hair deformation and the associated wall histology are host specific in that Betula root hairs show none of these responses when grown and inoculated in the experimental conditions described. The bacterially induced changes in root hair cell walls during deformation may create a chemically and physically modified substrate for Frankia penetration, and the deformation itself may serve to entrap and enclose the filamentous organism, allowing wall dissolution and entry. Thus these events represent a complex host response as a precondition to successful nodulation.

DEVELOPMENTAL MORPHOLOGY OF THE INFLORESCENCE IN HEXAPLOID WHEAT CULTIVARS WITH AND WITHOUT THE CULTIVAR NORIN 10 IN THEIR ANCESTRY

1973 ◽  
Vol 53 (1) ◽  
pp. 7-15 ◽  
Author(s):  
JOHN E. FISHER
Keyword(s):  
Triticum Aestivum ◽  
Apical Dominance ◽  
Triticum Aestivum L ◽  
Leaf Primordia ◽  
Developmental Pattern ◽  
Morphological Development ◽  
Wheat Cultivars ◽  
Developmental Morphology ◽  
Secale Cereale L ◽  
The Individual

The morphological development of the spike in short-statured hexaploid wheats (Triticum aestivum L.) derived from the cultivar Norin 10, and in Norin 10 as well, was markedly different from that in standard hexaploid wheats. In Norin 10 and its derivatives, the single ridges (slowly growing leaf primordia) on the elongating apex were considerably larger and spikelet primordia initiation and expansion were markedly delayed, resulting in a long apex with many single ridges. When spikelet development commenced, it was much more synchronous and hence gave rise to longer heads than in standard wheat in which spikelet development began soon after the start of the elongation of the apex. In most Norin 10 derivatives, more spikelets were initiated than in standard wheat. Apical dominance in the spike appeared to be stronger than in standard wheats. Also, apical dominance within the individual spikelets appeared to be greater, the net result being more fertile florets per spikelet. The developmental pattern of the spike of Norin 10 and its derivatives resembled, to a marked degree, the developmental pattern of rye (Secale cereale L.).

Pleopeltis pleopeltifolia (Polypodiopsida, Polypodiaceae), a poikilochlorophyllous desiccation-tolerant fern: anatomical, biochemical and physiological responses during water stress

2014 ◽  
Vol 62 (8) ◽  
pp. 647 ◽  
Author(s):  
Ana Paula Lorenzen Voytena ◽  
Bruno Degaspari Minardi ◽  
José Bonomi Barufi ◽  
Marisa Santos ◽  
Áurea Maria Randi
Keyword(s):  
Cell Walls ◽  
Sugar Content ◽  
Longitudinal Direction ◽  
Photosynthetic Parameters ◽  
Palisade Parenchyma ◽  
Abaxial Surface ◽  
Adaxial Surface ◽  
Anomocytic Stomata ◽  
Relevant Role ◽  
Notable Increase

While many ferns have been described as desiccation tolerant (DT), few studies have reported on the mechanisms they use to survive cell desiccation. Among the species belonging to the genus Pleopeltis, P. pleopeltifolia (Raddi) Alston (Polypodiopsida, Polypodiaceae) is a DT species endemic to Brazil. So as to better characterise the mechanisms of desiccation tolerance in ferns, the present study aimed to analyse frond anatomy and physiological changes associated with desiccation and rehydration of P. pleopeltifolia. Fronds are dorsiventral, with uniseriate epidermis. The epidermal cells have various shapes, tending to stretch in the longitudinal direction of the frond. Anticlinal cell walls are sinuous, and periclinal cell walls are convex. Anomocytic stomata are restricted to the abaxial surface. Trichome-type scales are found on both sides of the frond and may play a relevant role in rehydration of this plant when water is available. The mesophyll of the frond consists of palisade parenchyma, tending to a bistratified adaxial surface and spongy parenchyma on abaxial surface. The cuticle on the adaxial surface is conspicuous, ensuring better control of internal water balance. For physiological analyses, sporophytes were subjected to desiccation for 0, 5, 10 and 15 days and rehydration for 1 day. Sporophytes showed a sharp decline in water content when kept without irrigation, reaching 9.6% after 15 days, in addition to wilting and frond rolling. A significant increase in sugar content in fronds was noticeable during desiccation, which may favour a possible osmotic adjustment and vitrification. A notable increase in proline content during rehydration was observed in fronds. During the five initial days of desiccation, the chlorophyll and carotenoid contents decreased abruptly, but after 1 day of rehydration, they had partly recovered. The photosynthetic parameters analysed by fluorescence of chlorophyll a ceased completely after 15 days of desiccation but they had recovered near to pre-desiccation levels after 1 day of rehydration.

Cellular events during wound periderm formation in Dioscorea bulbifera bulbils

1989 ◽  
Vol 67 (10) ◽  
pp. 3090-3102 ◽  
Author(s):  
Ina Knobloch ◽  
Günter Kahl ◽  
Pierre Landré ◽  
Arlette Nougarède
Keyword(s):  
Cell Walls ◽  
Superficial Layer ◽  
Cell Nuclei ◽  
Meristematic Cells ◽  
Cellular Events ◽  
Fluorescence And Electron Microscopy ◽  
Deep Wound ◽  
Dioscorea Bulbifera ◽  
Cytoplasmic Ribosomes ◽  
Periderm Formation

The cytological events induced by a deep wound applied to Dioscorea bulbifera bulbils were studied using specific cytochemical methods and fluorescence and electron microscopy. Following wounding, a superficial layer with lignified (3rd h) and weakly suberized (6th h) cell walls formed in the original starchy parenchyma in contact with the wounded cells. Before the first mitoses (72nd h), an extensive dedifferentiation occurred in the underlying layers and involved reactivation of cell nuclei, nucleoli, and plastids. A concomitant aggregation of cytoplasmic ribosomes into polysomes occurred. Starch hydrolysis in the amyloplasts was evident before the first periclinal divisions. Periclinal divisions occurred in the reactivated cells from the second to the fourth layers beneath the wound. These newly meristematic cells could be divided into two to four new cells, leading to a periderm without a true phellogen. These covering layers degenerated during the period of lignification and weak suberization of cell walls. The thickness of the wound periderm depended on the age of the wounded bulbil.

The rotated-lamina syndrome. VI. The range from partial to near-complete rotation in Tiliaceae and Sterculiaceae

1997 ◽  
Vol 75 (1) ◽  
pp. 170-187 ◽  
Author(s):  
W. A. Charlton
Keyword(s):  
Key Words ◽  
Shoot Apex ◽  
Leaf Development ◽  
Leaf Primordia

The rotated-lamina syndrome is a condition most commonly found in dorsiventral shoots with distichous phyllotaxis. Typically, young laminae in bud appear to be rotated to face towards the upper side of the shoot. The syndrome arises by asymmetrical growth from leaf primordia that initially face the shoot apex in approximately the normal way. It was previously described in Tilia. Further genera of Tiliaceae and the closely related Sterculiaceae were examined for the presence of the syndrome. Altogether it was found in 9 genera of the 30 examined. The syndrome is well developed in representatives of Commersonia, Corchorus, and Pterospermum, and less well developed in Luehia seemannii. Expression of the syndrome is minimal in Luehia divaricata, Theobroma, Byttneria, and Grewia. In all cases with distichous phyllotaxis that were examined in these families, the leaf primordia show at least some asymmetry in development and consequently there appears to be a predisposition to lamina rotation within the group. The syndrome is probably becoming suppressed in cases with minimal expression. The situation in dorsiventral shoots of Corchorus and Byttneria is complicated by the presence of inflorescences that arise in a leaf-opposed position. Key words: Sterculiaceae, Tiliaceae, leaf, development, dorsiventrality, lamina rotation.

The initial protrusion of a leaf primordium can form without concurrent periclinal cell divisions

1971 ◽  
Vol 49 (9) ◽  
pp. 1601-1603 ◽  
Author(s):  
Donald E. Foard
Keyword(s):  
Gamma Rays ◽  
Shoot Apex ◽  
Cell Layer ◽  
Fold Increase ◽  
Leaf Primordia ◽  
Leaf Primordium ◽  
Initial Number ◽  
Wheat Grains ◽  
Cell Divisions ◽  
Number Of Cells

The view that periclinal cell divisions cause the initial protrusion of a leaf primordium may be tested by using ionizing radiation to prevent cell divisions without preventing growth. After receiving 800 krad of gamma rays, wheat grains containing embryos with three leaf primordia produce seedlings in which a fourth protrusion of the shoot apex forms unaccompanied by cell divisions. This protrusion without periclinal divisions occurs in the same phyllotactic position as that of the fourth leaf primordium in which periclinal divisions occur. In addition to proper phyllotactic position, the protrusion without cell divisions is formed by the outermost cell layer, as is the initial protrusion of a typical leaf primordium of wheat; moreover, the initial number of cells involved is the same in both kinds of protrusions. Therefore the fourth protrusion in seedlings from irradiated grain is interpreted as the initial protrusion of a leaf primordium that formed without periclinal cell divisions. Measured along the axis of greatest extension, the protrusions without cell divisions represent about a four- to eight-fold increase over the anticlinal dimension of the surface-cell layer in the embryo. These protrusions do not develop further. The absence of cell divisions limits the extent of primordial growth, but does not prevent its inception. Periclinal cell divisions do not cause the initial protrusion of a leaf primordium.

Morphological investigation of glandular hairs on Drosera capensis leaves with an ultrastructural study of the sessile glands

Botany ◽  
2013 ◽  
Vol 91 (4) ◽  
pp. 234-241 ◽  
Author(s):  
Yougasphree Naidoo ◽  
Samia Heneidak
Keyword(s):  
Cell Walls ◽  
Morphological Investigation ◽  
Adaxial Surface ◽  
Glandular Hairs ◽  
Red Hair ◽  
Leaf Surfaces ◽  
Radial Cell ◽  
Electron And Light Microscopy ◽  
First Time ◽  
Mucilage Secretion

Electron and light microscopy were employed to elucidate the types of glandular hairs on Drosera capensis L. leaves. Eight types of stalked and sessile hairs were found. One type of long-stalked red hair is present only along the margin of the adaxial surface of the leaf, and five types of short-stalked hairs exist mainly on the central part of the adaxial surface of the leaf. Two types of sessile glands are abundantly distributed on both the adaxial and abaxial leaf surfaces. The sessile glands of two head cells are described for the first time in D. capensis, and the sessile glands of four head cells are illustrated for the first time in the genus Drosera. The presence of a secretion from the two head cells of the sessile glands and the dark large vesicles inside them suggests a secretory function. Numerous wall ingrowths are present in the outer tangential and radial cell walls of the head cells of the sessile glands, increasing the surface area to facilitate mucilage secretion.

In vitro development of isolated leaf primordia of Matteuccia struthiopteris

1985 ◽  
Vol 63 (5) ◽  
pp. 916-919 ◽  
Author(s):  
P. Von Aderkas ◽  
G. Hicks
Keyword(s):  
Shoot Apex ◽  
Root Formation ◽  
Leaf Primordia ◽  
The Other ◽  
Secondary Development ◽  
In Vitro Development ◽  
Morphological Complexity ◽  
Developmental Fate ◽  
Vitro Development

Primordia (P2–P6) at the shoot apex were excised and cultured on Knudson's medium for a period of 4 weeks. The majority of primordia developed as leaves. The length, mass, and morphological complexity of these leaves were related to initial primordium age and height. There was a consistent trend toward the production of shorter, lighter, and less complex leaves from the younger, smaller initial explants. A second set of experiments traced the developmental fate of isolated primordia (P1–P4) over a longer period of time (12 weeks). Various kinds of secondary development were observed including bud and root development. Bud numbers decreased with primordial age. On the other hand, the rate of root formation increased.

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