Embryology of Isotoma petraea

1970 ◽  
Vol 18 (2) ◽  
pp. 213 ◽  
Author(s):  
IC Beltran
Keyword(s):  
Mother Cell ◽  
Embryo Sac ◽  
Endosperm Development ◽  
Ovule Development ◽  
Polygonum Type ◽  
Development Patterns ◽  
Embryo Formation ◽  
Ring Bivalents ◽  
Form Ring ◽  
Embryo Sac Formation

Ovule development, embryo sac formation, and embryogeny of I. Petraea are described. The ovules are anatropous, unitegmic, and tenuinucellar. Meiosis in the megaspore mother cell is regular and the chromosomes with terminalized chiasmata form ring bivalents at metaphase 1. The Polygonum type embryo sac, Scutellaria type endosperm development, and Solanad embryo formation correspond with development patterns in other members of the Lobeliaceae.

scholarly journals The mac1 Gene: Controlling the Commitment to the Meiotic Pathway in Maize

Genetics ◽  
1996 ◽  
Vol 142 (3) ◽  
pp. 1009-1020 ◽  
Author(s):  
William F Sheridan ◽  
Nadezhda A Avalkina ◽  
Ivan I Shamrov ◽  
Tatyana B Batyea ◽  
Inna N Golubovskaya
Keyword(s):  
Female Gametophyte ◽  
Embryo Sac ◽  
Flowering Plants ◽  
Normal Female ◽  
Ovule Development ◽  
Partial Sterility ◽  
Embryo Sac Formation ◽  
Female Gametophyte Development ◽  
Normal Meiosis ◽  
Pleiotropic Mutation

Abstract The switch from the vegetative to the reproductive pathway of development in flowering plants requires the commitment of the subepidermal cells of the ovules and anthers to enter the meiotic pathway. These cells, the hypodermal cells, either directly or indirectly form the archesporial cells that, in turn, differentiate into the megasporocytes and microsporocytes. We have isolated a recessive pleiotropic mutation that we have termed multiple archesporial cells1 (macl) and located it to the short arm of chromosome 10. Its cytological phenotype suggests that this locus plays an important role in the switch of the hypodermal cells from the vegetative to the meiotic (sporogenous) pathway in maize ovules. During normal ovule development in maize, only a single hypodermal cell develops into an archesporial cell and this differentiates into the single megasporocyte. In macl mutant ovules several hypodermal cells develop into archesporial cells, and the resulting megasporocytes undergo a normal meiosis. More than one megaspore survives in the tetrad and more than one embryo sac is formed in each ovule. Ears on mutant plants show partial sterility resulting from abnormalities in megaspore differentiation and embryo sac formation. The sporophytic expression of this gene is therefore also important for normal female gametophyte development.

Embryological studies in the compositae, I. Sporogenesis, Gametogenesis, and Embryogeny in Cotula australis (Less.) Hook. F

1962 ◽  
Vol 10 (1) ◽  
pp. 1 ◽  
Author(s):  
GL Davis
Keyword(s):  
Mother Cell ◽  
Megaspore Mother Cell ◽  
Embryo Sac ◽  
Subsequent Development ◽  
Pollen Grains ◽  
Archesporial Cell ◽  
Polygonum Type ◽  
Wall Formation ◽  
Chalazal Megaspore

Cotula australis has a discoid heterogamous capitulum in which the outermost three whorls of florets are female and naked. The bisexual disk florets are fully fertile and have a four-lobed corolla with four shortly epipetalous stamens. The anthers contain only two microsporangia. Wall formation and microsporogenesis are described and the pollen grains are shed at the three-celled condition. The ovule is teguinucellate and the hypodermal archesporial cell develops directly as the megaspore mother cell. Megasporogenesis is normal and the monosporio embryo sac develops from the chalazal megaspore. Breakdown of the nucellar epidermis takes place when the embryo sac is binucleate and its subsequent development follows the Polygonum type. The synergids extend deeply into the micropyle and one persists until late in embryogeny as a haustorium. The development of the embryo is of the Asterad type, and the endosperm is cellular. C. coronopifolia agrees with C. australis in the presence of only two microsporangia in each anther and the development of a synergid haustorium.

Gametogenesis in Galbulimima belgraveana (Himantandraceae)

1984 ◽  
Vol 32 (6) ◽  
pp. 605 ◽  
Author(s):  
N Prakash ◽  
DB Foreman ◽  
SJ Griffith
Keyword(s):  
Close Relationships ◽  
Embryo Sac ◽  
Pollen Grains ◽  
Mature Pollen ◽  
Ovule Development ◽  
Abaxial Side ◽  
Polygonum Type ◽  
Early Stages

The flowers of Galbulimima belgraveana (F. Muell.) Sprague are bisexual, calyptrate and protogynous. The numerous free stamens are laminar and arranged spirally on an elongated receptacle; only the middle stamens are fertile. There are four microsporangia embedded on the abaxial side of the microsporophyll. The tapetum is secretory and often double. A variety of spore tetrad types is produced. The mature pollen grains are single, monosulcate, scabrate, atectate, spheroidal and 2-celled. The carpels of a flower are initially free but later become concrescent so that a single fruit is formed. The ovules are anatropous, crassinucellar and bitegminal, and show an elongated embryo sac that conforms to the polygonum type of development. There is a massive parietal tissue in early stages of ovule development. In its embryological features, the species shows close relationships to the families Annonaceae and Degeneriaceae and, to a slightly lesser extent, the Magnoliaceae and Eupomatiaceae.

Ovule, embryo sac, embryo, and endosperm development in leafy spurge (Euphorbia esula)

1999 ◽  
Vol 77 (4) ◽  
pp. 599-610 ◽  
Author(s):  
Jeffrey S Carmichael ◽  
Sarena M Selbo
Keyword(s):  
Embryo Sac ◽  
Placental Tissue ◽  
Leafy Spurge ◽  
Endosperm Development ◽  
Protein Bodies ◽  
Euphorbia Esula ◽  
Invasive Weed ◽  
Polygonum Type ◽  
Nutrient Reserve ◽  
Endosperm Formation

Leafy spurge (Euphorbia esula L.) is a noxious, invasive weed that dominates many agriculturally important regions. While many research efforts are currently aimed at controlling the spread of this plant, relatively little is known about its sexual reproductive biology, especially from a structural perspective. This report describes key features of ovule development, embryogenesis, and endosperm formation in leafy spurge. Ovules are anatropous, bitegmic, and form a zigzag micropyle. A distinct elaisome (caruncle) and hypostase are formed as ovules mature. Obturators are present and are derived from placental tissue. The embryo sac conforms to the Polygonum type. A single embryo is formed in each seed and stores nutrients primarily as globoid protein bodies. Endosperm is persistent and also contains protein bodies as its primary nutrient reserve. Preliminary structural evidence is presented that indicates the potential for apomixis.Key words: leafy spurge, Euphorbiaceae, Euphorbia, ovule, endosperm, embryo.

Sporogenesis, Gametogenesis, and embryogeny of Wahlenbergia bicolor N. Lothian

1963 ◽  
Vol 11 (2) ◽  
pp. 152 ◽  
Author(s):  
G Want
Keyword(s):  
Mother Cell ◽  
Embryo Sac ◽  
Pollen Grains ◽  
Type A ◽  
Middle Layer ◽  
Anther Wall ◽  
Suspected Case ◽  
Polygonum Type ◽  
Chalazal Megaspore ◽  
Coastal Species

In Wahlenbergia bicolor, the anther wall is composed of four layers: epidermis, endothecium, middle layer, and tapetum. Wall formation and microsporogenesis are described, and the pollen grains are shed at the two-celled condition. The ovules are tenuinucellate, with a hypodermal archesporial cell which develops directly as the megaspore mother cell. Megasporogenesis is normal, and a monosporic eight-nucleate embryo sac of the most common Polygonum type develops from the chalazal megaspore. The antipodals degenerate before fertilization. The development of the embryo is of the solanad type. A suspected case of polyembryony was observed. The endosperm is cellular from its inception, and so conforms to the Codonopsis type. A micropylar and a chalazal haustoriurn, both consisting of two uninucleate cells, are formed from the endosperm. Comparative studies were made with a known but as yet undescribed coastal species of Wahlenbergia, and no differences were found.

Anther and Ovule Development in Tasmannia (Winteraceae)

1992 ◽  
Vol 40 (6) ◽  
pp. 877 ◽  
Author(s):  
N Prakash ◽  
AL Lim ◽  
FB Sampson
Keyword(s):  
Mother Cell ◽  
Female Gametophyte ◽  
Cell Plate ◽  
Basic Type ◽  
Ovule Development ◽  
Linear Tetrad ◽  
Polygonum Type ◽  
Secretory Type ◽  
Mother Cells ◽  
Female Gametophyte Development

Three species of Tasmannia R.Br. ex DC., T. glaucifolia, T. insipida and T. stipitata are studied. The anther is tetrasporangiate and its waU development conforms to the Basic type. The tapetum follows the secretory type of development. Cytokinesis in the microspore mother cells is simultaneous but an evanescent cell plate is present at telophase I and anaphase I1 during meiosis. Pollen tetrads are permanent and tetrahedral. The mature pollen is anaulcerate, reticulate and 2-celled. The ovule. is anatropous, bitegmic and crassinucellate. The micropyle in T. stipitata and T. Glaucifolia is formed by the inner integument only whereas in T. insipida it is formed by both the integuments and is zigzag in outline. Meiosis in the single megaspore mother cell produces a linear or T-shaped megaspore tetrad in T. stipitata and T. glaucifolia but only a linear tetrad in T. insipida. Female gametophyte development is of the monosporic Polygonum type. Fertilisation is porogamous; triple fusion and syngamy occur simultaneously.

The Cytology of Xanthisma texanum D.C. IV. Megasporogenesis and Embryo Sac Formation, Pollen Mitosis and Embryo Formation

1956 ◽  
Vol 83 (6) ◽  
pp. 428 ◽  
Author(s):  
C. A. Berger ◽  
E. J. Feeley ◽  
E. R. Witkus
Keyword(s):  
Embryo Sac ◽  
Pollen Mitosis ◽  
Embryo Formation ◽  
Embryo Sac Formation

Embryo sac and early ovule development in Oryzopsis miliacea and Stipa tortilis

1970 ◽  
Vol 48 (1) ◽  
pp. 27-41 ◽  
Author(s):  
Jack Maze ◽  
Lesly R. Bohm ◽  
Lyle E. Mehlenbacher Jr.
Keyword(s):  
Cell Division ◽  
Pollen Tube ◽  
Nuclear Division ◽  
Outer Integument ◽  
Embryo Sac ◽  
Ovule Development ◽  
Polygonum Type ◽  
Embryo Sac Development

The ovules of Stipa tortilis and Oryzopsis miliacea are hemianatropous, bitegmetic, and pseudocrassinucellate (sensu Davis 1966). The hemianatropous shape of the ovule is the result of characteristic patterns of cell division and enlargement in the chalazal area and areas alongside the embryo sac. Embryo sac development in both is Polygonum-type and both have proliferating antipodals. Endosperm is nuclear, although in O. miliacea it is atypical in that nuclear division is synchronous within one portion of the embryo sac, e.g. micropylar, but not synchronous between different portions of the embryo sac, e.g., micropylar and chalazal. Differences in ovule initiation, persistence of the outer integument, fate of the inner integument, nature of the nucellus, shape of the embryo sac, nature of the synergids, cytoplasm of the egg, polar nuclei, and endosperm exist between these two taxa. Both synergids of O. miliacea undergo changes before fertilization and one degenerates before fertilization. The pollen tube enters the embryo sac at the base of the persistent synergid. There is presently insufficient embryological data to permit meaningful speculation on relationships between Stipa and Oryzopsis. Embryologically, Stipa and Oryzopsis are festucoid grasses, as much other evidence indicates. Embryo sac development in the Gramineae is more similar to that of the Restionaceae than to that of the Cyperaceae. This is in contradiction to recent speculations on the relationships of the Gramineae.

scholarly journals Desarrollo del gametofito femenino de Tagetes patula (Asteraceae)

2017 ◽  
pp. 5
Author(s):  
Marcelina García-Aguilar ◽  
E. Mark Engleman ◽  
Eulogio Pimienta-Barrios
Keyword(s):  
Seed Development ◽  
Early Development ◽  
Mother Cell ◽  
Megaspore Mother Cell ◽  
Embryo Sac ◽  
Tagetes Patula ◽  
Polygonum Type ◽  
Chalazal Megaspore ◽  
The Family ◽  
Apomictic Reproduction

The genus Tagetes reproduces sexually by seed, but recent morphological and hybridization studies in Tagetes patula suggest an apomictic type of reproduction (seed development without fertilization). In order to determine the sexual or apomictic origen of the embryo, we have studied megasporogenesis, megagametogenesis and the early development of the embryo. Tagetes patula L. has a typical ovule for the family Asteraceae: anatropous, unitegmic, tenuinucellate and with basal placentation. A single hypodermal archesporial cell develops directly as the megaspore mother cell. Megaspogenesis is normal and embryo sac develops from the chalazal megaspore. The embryo sac is of the Polygonum type. Female ray flowers show irregularities in megagametophyte development such as formation of more than eight nuclei, inverted polarity and incomplete differentiation of the megagametophyte cells in mature flowers. These irregularities do not necessarily prove apomictic reproduction in Tagetes patula.

scholarly journals Embryology and cytogenetics of Eupatorium pauciflorum and E. intermedium (Compositae)

1998 ◽  
Vol 21 (4) ◽  
pp. 507-514 ◽  
Author(s):  
Maristela Sanches Bertasso-Borges ◽  
James Robert Coleman
Keyword(s):  
Embryo Sac ◽  
Pollen Grains ◽  
Endosperm Development ◽  
Egg Cell ◽  
Pollen Production ◽  
Polygonum Type ◽  
Total Absence ◽  
Basic Set ◽  
Autonomous Endosperm ◽  
Germinated Pollen

The embryology of Eupatorium pauciflorum indicates diplospory with autonomous endosperm development. The embryo sac is of the polygonum type and the polar nuclei mostly fuse before anthesis. The occurrence of precocious embryo and endosperm development in unopened florets, and the total absence of germinated pollen grains on exposed stigmas, as well as the absence of pollen tubes in the ovules, indicate agamospermy to be obligate and embryo and endosperm development autonomous. The study of microsporogenesis revealed the total absence of pollen production in consequence of microsporocyte degeneration before the onset of meiosis, which resulted in absolute male sterility. E. pauciflorum was demonstrated to be an autotriploid with a basic set of 10 chromosomes, each represented three times. Embryological studies showed E. intermedium to undergo reductive meiosis with tetrad formation during megasporogenesis, followed by monosporic embryo sac development of the polygonum type. The polar nuclei fuse before anthesis. The egg cell invariably attains anthesis still undivided, without precocious embryony. Meiosis of microsporogenesis results in the regular formation of 10 bivalents and the subsequent stages of microsporogenesis are normal. Stigmatic loads indicate the regular occurrence of pollination with viable, functional grains. Karyotypic studies revealed a complement of 20 chromosomes separable into 10 pairs. It is concluded that E. pauciflorum, as represented by the material studied, is apomictic while E. intermedium is sexual.

Sign in / Sign up

Export Citation Format

Share Document