The genesis of form in flax and lupin as shown by scale drawings of the shoot apex

1970 ◽  
Vol 18 (2) ◽  
pp. 167 ◽  
Author(s):  
RF Williams
Keyword(s):  
Shoot Apex ◽  
Serial Sections ◽  
Shoot Apices ◽  
Potential Value

Procedures for the preparation of perspective drawings from serial sections of shoot apices and similar small structures are described, and the properties of the projection are critically examined. The procedures have potential value for morphogenetic studies, and examples are given for shoot apices of flax and lupin. For lupin it is shown that the folioles arise in an oblique circle at the top of the emerging petiole. After the median member, they appear in pairs at unit plastochron intervals.

scholarly journals The riddle of phyllotaxis: exquisite control of divergence angle

2016 ◽  
Vol 85 (4) ◽  
Author(s):  
Takuya Okabe
Keyword(s):  
Plant Species ◽  
Shoot Apex ◽  
Evidence Base ◽  
Divergence Angle ◽  
Shoot Apices ◽  
Essential Point

Phyllotaxis studies published in German in the 1930s have reported intriguing regularity in the arrangement of incipient leaves on shoot apices of a wide variety of plant species. However, these studies have received little attention today, even though they provide a crucial evidence base for understanding this mathematical phenomena. Here I recapitulate the essential point by means of illustrative examples. It is emphasized that accurate control of apical divergence angle is at the heart of the numerical riddle of spiral phyllotaxis. The accurate patterning at the shoot apex has an unexpected evolutionary benefit of being optimally adaptive in the subsequent events of phyllotactic change to occur on an elongating shoot.

HISTOCHEMICAL CHANGES IN THE SHOOT TIP OF CAULIFLOWER DURING FLORAL INDUCTION

1967 ◽  
Vol 45 (7) ◽  
pp. 955-959 ◽  
Author(s):  
Sidki Sadik ◽  
J. L. Ozbun
Keyword(s):  
Shoot Apex ◽  
Dna Content ◽  
Deoxyribonucleic Acid ◽  
Floral Induction ◽  
Fold Increase ◽  
Bromophenol Blue ◽  
Shoot Apices ◽  
Fast Green ◽  
Floral Primordia ◽  
Histochemical Changes

Cauliflower plants were induced to flower after being grown at 42 °F for varying periods of time, depending on the cultivar. Some of the histochemical changes in the shoot apex at the beginning of, during, and after floral induction were studied. During floral induction there is about a 20-fold increase in the volume of nucleoli and about a 3-fold increase in volume of nuclei. Apices of vegetative plants stained with bromophenol blue at pH 2.3, show small and dense nucleoli, dense and granular nuclei, and a small amount of weakly staining cytoplasm. In contrast, cells of apices of induced plants stained with bromophenol blue at pH 2.3, show large and dense nucleoli, large and weakly staining nuclei; however, these cells contain more and denser cytoplasm. Sections of vegetative and induced apices stained with alkaline fast green stained differently from those stained with bromophenol blue. Nucleoli did not stain and cytoplasm stained faintly with fast green while chromosomes stained strongly. Deoxyribonucleic acid (DNA) content of vegetative and induced apices are similar. Shoot apices of vegetative plants contained little or no starch. However, shoot apices of plants grown at 42 °F accumulate large amounts of starch. Floral primordia which develop into functional flowers are glutted with starch, while floral primordia which abort are void of starch.

Etude de la teneur en DNA nucléaire dans le méristème apical des tiges du Celosia cristata (Amarantacées) en fonction de la photopériode

1979 ◽  
Vol 57 (24) ◽  
pp. 2760-2765 ◽  
Author(s):  
D. Driss-Ecole
Keyword(s):  
Shoot Apex ◽  
Nuclear Dna ◽  
Intermediate Phase ◽  
Central Zone ◽  
Shoot Apices ◽  
Two Samples ◽  
Dna Values ◽  
Celosia Cristata ◽  
Zone Characteristic ◽  
Cytophotometric Study

Two samples of plants of Celosia cristata, a quantitative short-day plant, were grown in an 8-h or a 16-h day. The shoot apices were collected at 11, 15, 18, and 28 days in order to carry out a cytophotometric study of the nuclear DNA in the corpus. This distribution of the DNA values was analyzed statistically using the χ2 test. At the beginning of development, for both 8-h day and 16-h day plants, the DNA content of the majority of the nuclei is at the 2C level. Then the percentage 2C–4C or 4C nuclei increases, slowly for the plants grown under a 16-h photoperiod and quickly for the others. At the 28th day, the Gaussian distribution of DNA values indicates that the state reached by the meristems is quite different. Between the 18th day and the 28th day of culture, ontogenesis of the shoot apex goes through a critical period. At the end of this period, shoot apices of the plants grown under a 16-h photoperiod are in the intermediate phase with a majority of nuclei in the synthetic phase (S) or in the postsynthetic phase (G2). Simultaneously, structural modifications of the axial zone give rise to a central zone characteristic of the fasciation of the shoot apex. In plants grown with an 8-h photoperiod, the shoot apex goes through the prefloral phase with more numerous nuclei in the presynthetic phase (G1) or in the synthetic one (S). For each sample the nuclei clustered in a particular phase of the cell cycle indicate that a certain synchronism of the cell cycles in the corpus takes place. These results are compared with those recently obtained by other authors working with different plants.

MICROPROPAGATION OF Helianthus maximiliani (Schrader) BY SHOOT APEX CULTURE / MICROPROPAGACION DE Helianthus maximiliani (Schrader) POR EL CULTIVO DE VAINAS DE LOS VASTAGOS / MICROPROPAGATION DE L’Helianthus maximiliani (Schrader) AU MOYEN DE LA CULTURE DE L’APEX DE LA POUSSE

Helia ◽  
2001 ◽  
Vol 24 (34) ◽  
pp. 63-68 ◽  
Author(s):  
Vasić Dragana ◽  
Škorić Dragan ◽  
Alibert Gilbert ◽  
Miklič Vladimir
Keyword(s):  
Silver Nitrate ◽  
Shoot Apex ◽  
Casein Hydrolysate ◽  
Shoot Tips ◽  
Nodal Segments ◽  
Shoot Apices ◽  
Skoog Medium ◽  
Leaf Mesophyll ◽  
Murashige And Skoog Medium

SUMMARYH.maximiliani was micropropagated using culture of shoot apices on modified Murashige and Skoog medium (DV). Further propagation of in vitro grown plants was done by culture of their nodal segments and shoot tips on the same medium supplemented with phloridzin, silver nitrate and casein hydrolysate (DV'). Rooting was induced by dipping the explants into IBA solution prior culture. Viable protoplasts (90%) were isolated from leaf mesophyll. These protoplasts divided (18%) in culture in agarose droplets.

In vitro morphogenesis in Osmunda cinnamomea. The role of the shoot apex in early leaf development

1969 ◽  
Vol 47 (4) ◽  
pp. 575-580 ◽  
Author(s):  
G. S. Hicks ◽  
T. A. Steeves
Keyword(s):  
Shoot Apex ◽  
Leaf Development ◽  
Leaf Primordia ◽  
Shoot Apices ◽  
In Vitro Morphogenesis ◽  
Indeterminate Growth ◽  
Nutrient Culture ◽  
Determinate Growth

In sterile nutrient culture, shoot apices of the rhizome of Osmunda cinnamomea L., devoid of all visible foliar primordia, quickly give rise to dorsiventral leaf primordia at a presumptive leaf site (I1). It was established that these primordia were irreversibly determined as leaves. To examine the morphogenetic role of the shoot apex in governing early leaf development, this site was permanently isolated from the shoot apex by a single tangential cut. Usually, radially symmetrical shoots of indeterminate growth arose at I1 as a result of this surgery. By contrast, when organic continuity between I1 and the shoot apex was only temporarily interrupted by a cut which was subsequently allowed to heal, normally oriented dorsiventral leaf primordia formed most frequently at I1. These, too, were determined as leaves. It was concluded that the shoot apex serves as a source of determinative influences for the nascent primordium, imposing dorsiventrality and a pattern of determinate growth on the leaf site.

scholarly journals Ontogenetic changes of phyllotaxis in Anagallis arvensis L.

2014 ◽  
Vol 64 (4) ◽  
pp. 319-325 ◽  
Author(s):  
Dorota Kwiatkowska
Keyword(s):  
Shoot Apex ◽  
Regular Sequence ◽  
Internode Elongation ◽  
Spiral Pattern ◽  
Ontogenetic Changes ◽  
Flower Buds ◽  
Shoot Apices ◽  
Flower Primordia ◽  
Number Of Leaves ◽  
The Common

During the ontogeny of <i>Anagallis</i> spontaneous changes of phyllotaxis appear in a regular sequence. The initial decussate pattern is followed by spiral Fibonacci phyllotaxis, this in turn, by a trimerous pattern, and finally Lucas spiral phyllotaxis is formed. In the course of the first and most common phyllotactic transition, from the decussate to spiral Fibonacci pattern, changes in primordia arrangement occur only within a limited sector of the apex circumference. In the complementary sector, primordia emerge as if the decussate phyllotaxis continued. It is likely that similar circumferential discontinuity accounts for further transitions. The common ontogenetic sequence of patterns in <i>Anagallis</i> is such that, theoretically, each transition requires minimal changes in shoot apex geometry. Although the meristem in <i>Anagallis</i> is able to produce primordia either in whorls or spirally, the elongated shoots of this plant seem to have leaves exclusively in whorls. It appeared that in shoots with an initially spiral pattern, leaves can be clustered in pseudo-whorls due to the uneven internode elongation. Pseudowhorls are composed usually of three (Fibonacci) or four (Lucas) leaves of successive nodes. The number of leaves in a pseudo-whorl equals the number of leaves positioned on one revolution of the ontogenetic helix, which is different in these two spiral patterns. In shoot apices with whorled phyllotaxis, the leaf and flower primordia of a whorl are of different size. On elongated shoots, flower buds emerging in the axils of leaves of one whorl also differ in size.

scholarly journals A novel WD40-repeat protein involved in formation of epidermal bladder cells in the halophyte quinoa

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Tomohiro Imamura ◽  
Yasuo Yasui ◽  
Hironori Koga ◽  
Hiroki Takagi ◽  
Akira Abe ◽  
...  
Keyword(s):  
Abiotic Stress ◽  
Shoot Apex ◽  
In Silico ◽  
Genetic Basis ◽  
Wd40 Repeat ◽  
Shoot Apices ◽  
Saline Tolerance ◽  
Trichome Formation ◽  
Bladder Cells ◽  
And Function

AbstractHalophytes are plants that grow in high-salt environments and form characteristic epidermal bladder cells (EBCs) that are important for saline tolerance. To date, however, little has been revealed about the formation of these structures. To determine the genetic basis for their formation, we applied ethylmethanesulfonate mutagenesis and obtained two mutants with reduced levels of EBCs (rebc) and abnormal chloroplasts. In silico subtraction experiments revealed that the rebc phenotype was caused by mutation of REBC, which encodes a WD40 protein that localizes to the nucleus and chloroplasts. Phylogenetic and transformant analyses revealed that the REBC protein differs from TTG1, a WD40 protein involved in trichome formation. Furthermore, rebc mutants displayed damage to their shoot apices under abiotic stress, suggesting that EBCs may protect the shoot apex from such stress. These findings will help clarify the mechanisms underlying EBC formation and function.

Ontogenetic Studies on the Juvenile Leaves of Phoenix dactylifera L

1974 ◽  
Vol 22 (4) ◽  
pp. 689 ◽  
Author(s):  
D Padmanabhan ◽  
S Veerasamy
Keyword(s):  
Shoot Apex ◽  
Phoenix Dactylifera ◽  
Differential Growth ◽  
Adaxial Side ◽  
Shoot Apices ◽  
Abaxial Side ◽  
Phoenix Dactylifera L ◽  
Adult Leaf ◽  
Continuous Sheet ◽  
Cotyledonary Sheath

The ontogeny of seedling leaves or eophylls of Phoenix dactylifera was studied from foliar initiation to the stage of laminal maturation. During germination, the embryonal axis is carried deeper into the soil by the elongating cotyledonary sheath. As soon as the root and shoot apices become active the elongation stops. The first foliar organ produced by the shoot apex is a prophyll, a structure that has a sheath but no lamina. The second product of the shoot apex is the first eophyll, which is simple, lanceolate, plicate and devoid of haut. The plications arise by the process of schizogenous splitting of cells of the laminal meristem and not by differential growth or by 'invagination' as reported by earlier authors working on other palm genera. The eophyll differs from the adult leaf in the mode of splitting and in the number of plications produced. The adaxial splits occurring in the eophyll start from the epidermis and proceed inwards, whereas they are internal for the most part and leave a continuous sheet of tissue (haut) in the adult leaf. The first eophyll develops only one split on either side of the rachis-petiole axis on the adaxial side followed by a similar splitting on the abaxial side. This limits the number of plications to a minimum. Ontogeny of the vasculature of the eophyll is traced from early stages.

Three-Dimensional Reconstruction Using Stereo Pairs from Serial Thick Sections

1977 ◽  
Vol 35 ◽  
pp. 562-563
Author(s):  
Robert Glaeser ◽  
Thomas Bauer ◽  
David Grano
Keyword(s):  
Three Dimensional ◽  
Dimensional Structure ◽  
Serial Sections ◽  
Thin Sections ◽  
3 Dimensional ◽  
Transmission Electron ◽  
Freeze Dried ◽  
Dimensional Reconstruction ◽  
Stereo Imagery ◽  
Whole Mounts

In transmission electron microscopy, the 3-dimensional structure of an object is usually obtained in one of two ways. For objects which can be included in one specimen, as for example with elements included in freeze- dried whole mounts and examined with a high voltage microscope, stereo pairs can be obtained which exhibit the 3-D structure of the element. For objects which can not be included in one specimen, the 3-D shape is obtained by reconstruction from serial sections. However, without stereo imagery, only detail which remains constant within the thickness of the section can be used in the reconstruction; consequently, the choice is between a low resolution reconstruction using a few thick sections and a better resolution reconstruction using many thin sections, generally a tedious chore. This paper describes an approach to 3-D reconstruction which uses stereo images of serial thick sections to reconstruct an object including detail which changes within the depth of an individual thick section.

Correlated Studies of Cellular Interactions Using TEM, Freeze Etching, and SEM

1974 ◽  
Vol 32 ◽  
pp. 320-321
Author(s):  
J. P. Revel
Keyword(s):  
Developmental Stages ◽  
Three Dimensional ◽  
Cell Movement ◽  
Cellular Interactions ◽  
Serial Sections ◽  
Cell Sheets ◽  
Freeze Etching ◽  
Early Developmental

Movement of individual cells or of cell sheets and complex patterns of folding play a prominent role in the early developmental stages of the embryo. Our understanding of these processes is based on three- dimensional reconstructions laboriously prepared from serial sections, and from autoradiographic and other studies. Many concepts have also evolved from extrapolation of investigations of cell movement carried out in vitro. The scanning electron microscope now allows us to examine some of these events in situ. It is possible to prepare dissections of embryos and even of tissues of adult animals which reveal existing relationships between various structures more readily than used to be possible vithout an SEM.

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