Embryology of Calypso bulbosa. II. Embryo development

1992 ◽  
Vol 70 (3) ◽  
pp. 461-468 ◽  
Author(s):  
Edward C. Yeung ◽  
Sandra K. Law
Keyword(s):  
Cell Division ◽  
Key Words ◽  
Embryo Development ◽  
Basal Cell ◽  
Embryo Sac ◽  
Terminal Cell ◽  
Starch Granules ◽  
Terrestrial Orchid ◽  
Storage Products

Calypso bulbosa is a terrestrial orchid that grows in north temperate regions. After fertilization, the zygote enlarges and grows towards the chalazal end of the embryo sac. An unequal cell division gives rise to a smaller terminal cell and a larger basal cell. A constriction forms in the basal cell. Further growth results in a U-shaped embryo. Two patterns of initial terminal cell division have been observed. In a majority of developing embryos, the terminal cell first divides periclinally and then anticlinally. In approximately 5% of the embryos, the initial division of the terminal cell is anticlinal. Despite differences in early cell division patterns, subsequent embryo development is the same. The suspensor consists of a large, highly vacuolated basal cell and a 4-celled filamentous region. Highly conspicuous starch granules are present within the basal cell of the suspensor. At maturity, the embryo proper is small, consisting of approximately 24 cells and lacking marked differentiation of the apical end. Starch and lipid are the main storage products within the embryo proper. Key words: Calypso orchids, embryo development, suspensor.

Embryo and endosperm development in coriander (Coriandrum sativum)

Botany ◽  
2011 ◽  
Vol 89 (4) ◽  
pp. 263-273 ◽  
Author(s):  
Edward C. Yeung ◽  
Steve Bowra
Keyword(s):  
Basal Cell ◽  
Structural Changes ◽  
Cell Lineage ◽  
Endosperm Development ◽  
Coriandrum Sativum ◽  
Terminal Cell ◽  
Primary Endosperm Nucleus ◽  
Cell Degeneration ◽  
Storage Products ◽  
And Storage

Coriander ( Coriandrum sativum L.) seeds are rich in lipids and are potentially important sources of oils for industrial use. The objective of this study was to determine the details of embryo and endosperm development and the sites of storage reserves using microscopy and histochemistry. In coriander, the zygote divides unequally, giving rise to a large basal cell and a smaller terminal cell. Subsequent divisions in the basal cell result in the formation of a suspensor, and divisions in the terminal cell give rise to cells of the embryo proper. A defined cell lineage is absent in the formation of the proembryo. Contrary to other flowering plants, the suspensor persists as the embryo matures and storage products are present within the cytoplasm of the suspensor cells. After fertilization, the primary endosperm nucleus divides rapidly, resulting in a large syncytium of nuclei and cytoplasm. The rapid nuclear divisions occur prior to the first division of the zygote. Cellularization of the endosperm occurs soon after. Within the developing seed, the endosperm can be separated into two main regions, i.e., the “embryo surround region” (ESR) of endosperm and the persistent endosperm. The endosperm cells in these two regions have different cell fates and storage products. In the ESR, the endosperm cells undergo distinct structural changes and are destined to degenerate. These endosperm cells produce a significant amount of polysaccharides and these materials appear to aid in cell separation prior to cell degeneration. At the boundary of the ESR, the endosperm cells are partially degenerated with a large accumulation of lipids. The bulk of the endosperm cells next to the seed coat persist and they are responsible for the production and accumulation of storage lipids and proteins.

The embryology of Arceuthobium pusillum

1968 ◽  
Vol 46 (12) ◽  
pp. 1473-1476 ◽  
Author(s):  
F. H. Tainter
Keyword(s):  
Basal Cell ◽  
Embryo Sac ◽  
Sperm Nucleus ◽  
The Other ◽  
Terminal Cell ◽  
Transverse Wall

Megasporogenesis in Arceuthobium pusillum begins in March–April, 19 months after emergence of the pistillate aerial shoots. The embryo sacs are fully developed within 1 month. The first division results in a functional dyad and a nonfunctional dyad. The nucleus in the nonfunctional dyad divides once and the resulting nuclei disintegrate. Meiosis in the functional dyad follows immediately. Development of the embryo sac is of the bisporic Allium type. Staminate and pistillate aerial shoots flower in April–May. Fertilization occurs within several days after pollen has adhered to and germinated on the stigmas of pistillate flowers. One sperm nucleus fuses with the egg nucleus, the other with the polar nuclei. A haustorial extension then elongates downward into the ovarian papilla and becomes filled with a file of endosperm cells. Concurrently a uniseriate layer of endosperm has developed around the zygote. The endosperm then grows to a rather massive size before the zygote begins development. A transverse wall forms after the first division of the zygote. The terminal cell is bisected first, followed by bisection of the basal cell. Succeeding anticlinal and periclinal divisions result in growth of the proembryo. Embryonic protoderm is visible as a distinct tissue by the time the embryo has assumed an ovoid shape. When the seeds are forcibly expelled from their fruits in mid-September, the embryo has four distinct histological zones: protoderm, promeristem, ground meristem, and procambium.

scholarly journals Odorant receptors regulate the final glomerular coalescence of olfactory sensory neuron axons

2015 ◽  
Vol 112 (18) ◽  
pp. 5821-5826 ◽  
Author(s):  
Diego J. Rodriguez-Gil ◽  
Dianna L. Bartel ◽  
Austin W. Jaspers ◽  
Arie S. Mobley ◽  
Fumiaki Imamura ◽  
...  
Keyword(s):  
Cell Division ◽  
Sensory Neuron ◽  
Basal Cell ◽  
Olfactory Nerve ◽  
Olfactory Sensory Neuron ◽  
Odorant Receptors ◽  
Axon Extension ◽  
Mapping Strategy ◽  
Two Phases

Odorant receptors (OR) are strongly implicated in coalescence of olfactory sensory neuron (OSN) axons and the formation of olfactory bulb (OB) glomeruli. However, when ORs are first expressed relative to basal cell division and OSN axon extension is unknown. We developed an in vivo fate-mapping strategy that enabled us to follow OSN maturation and axon extension beginning at basal cell division. In parallel, we mapped the molecular development of OSNs beginning at basal cell division, including the onset of OR expression. Our data show that ORs are first expressed around 4 d following basal cell division, 24 h after OSN axons have reached the OB. Over the next 6+ days the OSN axons navigate the OB nerve layer and ultimately coalesce in glomeruli. These data provide a previously unidentified perspective on the role of ORs in homophilic OSN axon adhesion and lead us to propose a new model dividing axon extension into two phases. Phase I is OR-independent and accounts for up to 50% of the time during which axons approach the OB and begin navigating the olfactory nerve layer. Phase II is OR-dependent and concludes as OSN axons coalesce in glomeruli.

Histopathology of Albugo tragopogonis on stems and petioles of sunflower

1999 ◽  
Vol 77 (1) ◽  
pp. 175-178
Author(s):  
H Krüger ◽  
A Viljoen ◽  
P S Van Wyk
Keyword(s):  
Cell Division ◽  
Key Words ◽  
Helianthus Annuus ◽  
Systemic Infection ◽  
Infected Tissue ◽  
Tissue Integrity ◽  
Callose Formation ◽  
Stem Lesions ◽  
Lignin Deposition

Stem lesions in sunflower caused by Albugo tragopogonis (Pers.) S.F. Gray developed individually from primary infections and did not result from a systemic infection. Cell division and callose formation were not observed, but weak lignin deposition occurred in infected tissues. Hyphae occurred intercellularly in stems in the cortex, cambium, vascular rays, and pith. In petioles parenchymatous tissue was heavily colonized in contrast to lightly colonized collenchymatous hypodermis. The middle lamellae of cells in infected tissue were dissolved, and cells degenerated and eventually collapsed. Stem infections lead to deterioration of tissue integrity, weakening of stems, and finally to lodging of stems (breaking over).Key words: Albugo tragopogonis, Helianthus annuus, histopathology, stem lodging.

Effects of Drought and High Temperature on Grain Growth in Wheat

1984 ◽  
Vol 11 (6) ◽  
pp. 553 ◽  
Author(s):  
ME Nicolas ◽  
RM Gleadow ◽  
MJ Dalling
Keyword(s):  
Cell Division ◽  
High Temperature ◽  
Cell Size ◽  
Dry Matter ◽  
Cell Number ◽  
Limiting Factor ◽  
Dry Matter Accumulation ◽  
Starch Granules ◽  
Maximum Cell ◽  
Effects Of Drought

The effects of two levels of temperature and of water supply on grain development of wheat (cv. Warigal) were studied by imposing treatments during the early or late period of cell division. High temperature (28°C day/20°C night) accelerated development of the grain. Dry matter accumulation and cell division proceeded at a higher rate but had a shorter duration in the high temperature treatments. Maximum cell number, final cell size and the number of large starch granules per cell were not significantly reduced by high temperature. Drought and drought × high temperature reduced the storage capacity of the grain, with a decrease in number of cells and starch granules in the endosperm. Cell size was also reduced when treatments were imposed late during cell division. Duration of dry matter accumulation and cell division was reduced in the drought and drought × high temperature treatments. The combined effects of drought and high temperature were much more severe than those of each separate treatment. The amount of sucrose per cell was similar in all treatments. It appears unlikely that the supply of sucrose to the endosperm cells is the main limiting factor of dry matter accumulation in both drought and high temperature treatments.

Location of α-amylase/subtilisin inhibitor during kernel development and germination

1995 ◽  
Vol 73 (7) ◽  
pp. 982-990 ◽  
Author(s):  
R. D. Hill ◽  
S. M. Gubbels ◽  
L. Boros ◽  
M. J. Sumner ◽  
A. W. MacGregor
Keyword(s):  
Hordeum Vulgare ◽  
Key Words ◽  
Protein Bodies ◽  
Starch Granules ◽  
Starchy Endosperm ◽  
Kernel Development ◽  
Germination Inhibitor ◽  
Subtilisin Inhibitor ◽  
Immunohistochemical Techniques

The location of an endogenous α-amylase/subtilisin inhibitor in developing and germinating barley (Hordeum vulgare, cv. Bonanza) was determined using immunohistochemical techniques. The inhibitor was found within protein bodies of cells containing starch granules in the starchy endosperm and embryo of developing caryopses. It could be detected as early as 2 weeks postanthesis in both organs. Upon germination, inhibitor was released from protein bodies, resulting in increased detection of the protein in regions of the starchy endosperm in which storage mobilization was occurring. Antibodies to α-amylase revealed large quantities of this protein in the same regions. Key words: α-amylase, α-amylase/subtilisin inhibitor, barley, germination, kernel development, starch.

Evidence for a fungal liaison between Corallorhiza trifida (Orchidaceae) and Pinus contorta (Pinaceae)

1995 ◽  
Vol 73 (6) ◽  
pp. 862-866 ◽  
Author(s):  
Carla D. Zelmer ◽  
R. S. Currah
Keyword(s):  
Key Words ◽  
Pinus Contorta ◽  
Woody Plant ◽  
Orchid Mycorrhiza ◽  
Terrestrial Orchid ◽  
Bright Yellow ◽  
Fungal Hyphae ◽  
Triple Symbiosis ◽  
Relative Inability ◽  
Slow Growing

Corallorhiza trifida Châtelain, or pale coral root orchid, is a heterotrophic, leafless, rootless, terrestrial orchid with a circumboreal distribution. Because of its relative inability to photosynthesize, the orchid obtains energy through the digestion of fungal hyphae that grow within the cells of its contorted, yellowish, coralloid rhizomes. Recently, we isolated and cultured strains of a slow-growing basidiomycete with bright yellow, clamped hyphae that are typical of the fungal cells present in C. trifida endomycorrhizas from different treed habitats at widely distributed locations in the northern hemisphere. By inoculating the roots of Pinus contorta Douglas ex Loudon seedlings with this fungus we were able to demonstrate its ability to form distinctive ectomycorrhizas with an ectotrophic, woody plant. The formation of endomycorrhizas with C. trifida and ectomycorrhizas with P. contorta indicates that in nature a triple symbiosis, with a circumboreal distribution, exists among certain trees, the coral root orchid, and this yellow basidiomycete that links the two and functions as a mycorrhizal symbiont in both. Key words: Corallorhiza trifida, orchid mycorrhiza, triple symbiosis, ectomycorrhiza, Pinus contorta.

scholarly journals Reticulocytes II: Reexamination of the in vivo survival of stress reticulocytes

Blood ◽  
1990 ◽  
Vol 75 (9) ◽  
pp. 1877-1882 ◽  
Author(s):  
NA Noble ◽  
QP Xu ◽  
LL Hoge
Keyword(s):  
Cell Division ◽  
Terminal Cell ◽  
Intrinsic Properties ◽  
Over Time

Abstract Very young reticulocytes are released into the circulation in response to the stress of anemia. These stress reticulocytes have shortened in vivo survival when transfused into normal recipients, and are generally considered to be abnormal because they have skipped a terminal cell division. We reevaluated one aspect of their abnormality: that of in vivo survival. Using methodology that accounted for all cells transfused, in vivo survival of both normal and stress reticulocytes was investigated in both normal and anemic recipients. The experiments demonstrate that: (1) survival of reticulocytes is normal only when normal reticulocytes are injected into nonanemic animals; (2) intrinsic properties of stress reticulocytes lead to their immediate removal from the circulation by normal recipients to a significantly greater extent than by anemic recipients; and (3) both stress and normal reticulocytes are removed at an accelerated rate over time by anemic recipients. Taken together, the data indicate that in the course of becoming anemic, an adaptation occurs that allows cells produced during anemia to circulate considerably longer in anemic animals than they could in normal nonanemic animals. Other studies disclosed that increased reticulocyte survival in anemic animals could not be attributed to reticuloendothelial overload, but is induced by adaptation of the spleen, decreasing its removal of stress reticulocytes.

Anther, ovule, seed, and nucellar embryo development in Citrus sinensis cv. Valencia

1995 ◽  
Vol 73 (10) ◽  
pp. 1567-1582 ◽  
Author(s):  
Anna M. Koltunow ◽  
Kathleen Soltys ◽  
Nobumasa Nito ◽  
Stuart McClure
Keyword(s):  
Embryo Development ◽  
Fruit Development ◽  
Embryo Sac ◽  
Morphological Characteristics ◽  
Central Portion ◽  
Seed Formation ◽  
Nucellar Embryony ◽  
Nucellar Embryo ◽  
Unfertilized Ovules

'Valencia' orange, a commercially important cultivar of Citrus, forms polyembryonic seeds by an apomictic process called nucellar embryony in which many embryos initiate directly from nucellar cells surrounding the sexual embryo sac. We observed anther, ovule, seed, and fruit development in relation to nucellar embryo development in seeds and unfertilized ovules of 'Valencia'. Pollination and fertilization are required to set fruit in 'Valencia', and low seed set was found to be related to defects in both male and female gametogenesis. Nucellar embryo initial cells were evident histologically in ovules of flowers just prior to anthesis. However, in vitro culture of ovules from flowers at different prepollination stages showed that embryos could develop from ovules cultured as early as the binucleate stage of megagametogenesis in which nucellar initial cells were absent histologically. During fruit development, the timing and sequence of the early events of nucellar embryo formation were synchronous in seeds and unfertilized ovules, indicating a co-ordinated control of embryo development in spatially and developmentally distinct structures. In both developing seeds and unfertilized ovules, embryo initial cells first formed thick walls, which isolated them from surrounding maternal tissue. In later stages, the cell walls thinned in some initial cells and embryogenesis became asynchronous. Cleavage of embryogénie cells coincided with degenerative processes linked to embryo sac expansion in seeds and to a previously unreported, localized degeneration in the central portion of the nucellus in unfertilized ovules. Some initial cells never divided. Nucellar embryo development was restricted to the central portion of unfertilized ovules and to the micropylar region of seeds. Only fertilized ovules had the capacity to form mature polyembryonic seeds. In unfertilized ovules a specialized vascular structure formed linking developing embryos to the chalazal vasculature of the ovule. Embryo development arrested at the globular stage in unfertilized ovules and the integuments differentiated to form a seed coat. The timing of reproductive events described was linked to floral and fruit morphological characteristics to facilitate molecular characterization of nucellar embryogenesis and seed formation in this cultivar. Key words: Citrus, nucellar embryony, seed, ovule, apomixis.

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