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.

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.

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.

Megasporogenesis and megagametogenesis in Pelargonium × hortorum

1973 ◽  
Vol 51 (3) ◽  
pp. 607-612 ◽  
Author(s):  
Annie H. Tsai ◽  
Patricia M. Harney ◽  
R. L. Peterson
Keyword(s):  
Mother Cell ◽  
Megaspore Mother Cell ◽  
Outer Integument ◽  
Embryo Sac ◽  
Mature Embryo ◽  
Polar Nucleus ◽  
Archesporial Cell ◽  
Linear Tetrad ◽  
Polygonum Type ◽  
Cell Functions

The ovary of Pelargonium × hortorum contains five pairs of superposed ovules in five locules. These ovules are bitegmic and crassinucellar and the upper ovule of each pair is campylotropous while the lower one is anatropous. A single archesporial cell functions directly as the megaspore mother cell. Meiotic division of the megaspore mother cell results in the formation of a linear tetrad of megaspores of which the chalazal megaspore is functional. Embryo sac development is of the polygonum type. Rapid degeneration of the three antipodals occurs followed by the fusion of the two polar nuclei. Therefore, the mature embryo sac contains the egg, the two synergids, and the fused polar nucleus. Double fertilization takes place. Ninety-two percent of the fertilized ovules of P. × hortorum cv. ‘Purple Heart’ are found in the upper position.The two integuments are initiated before the differentiation of the archesporial cell. Cells of the outer layer of the outer integument and the inner layer of the inner integument deposit tannins. The nucellus develops through divisions of the parietal cells of the nucellar epidermal cells.

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.

Floral Morphology of the family compositae, III. Embryology of Siegesbeckia orientalis L

1965 ◽  
Vol 13 (1) ◽  
pp. 1 ◽  
Author(s):  
S Misra
Keyword(s):  
Vascular Bundle ◽  
Floral Morphology ◽  
Embryo Sac ◽  
Cell Plate ◽  
Pollen Grain ◽  
Polygonum Type ◽  
Outermost Layer ◽  
The Family ◽  
Siegesbeckia Orientalis ◽  
Ray Florets

The capitulum is heterogamous and globose with a biseriate involucre, the outer most bracts being radiating and glandular wuhile the inner are boat-shaped, enclosing the ray florets. The disc florets are also subtended by bracts, although one or two central bracts do not bear florets. The corolla of the ray florets is bilabiate in material collected from Mussoorie, India, while posterior lip is suppressed in that form Mt.Abu. The stamen and the style correspond to types 2 and V11 respectively of Small (1919). Occasional staminodes in the ray florets represent a reversionary feature. The development and structure of the microsporangium is described. An ephemeral cell plate is formed after meiosis 1 of the sporocytes. The mature pollen grain is tricellular; the male garnets are elongated and laxly spiral. The ovule develops slightly to one side of the base of the loculus, and a funicular vascular bundle branches in the integument. The endothelium is uniseriate, later becoming multiseriate at the two ends of the embryo sac, and it develops a cuticle on its inner face which persists in the seed after the endothelium degenerates. The development of the embryo sac is of the Polygonum type. The antipodals and one synergid become haustorial after fertilization. Supernumery pollen tubes were noted. Failure of fertilization in exceptional cases results in unusaul behaviour of the endothelium, degeneration of the embryo sacs, and seed sterility. The endosperm is nuclear, later becoming cellular, and is outermost layer persists in the seed. Embryogeny is of the asterad type.

Ovule-to-seed development in Dovyalis caffra (Salicaceae: Flacourtieae) with notes on the taxonomic significance of the extranucellar embryo sac

Bothalia ◽  
2005 ◽  
Vol 35 (1) ◽  
pp. 101-108 ◽  
Author(s):  
E. M. A. Steyn ◽  
A. E. Van Wyk ◽  
G. F. Smith
Keyword(s):  
Seed Development ◽  
Embryo Sac ◽  
Taxonomic Significance ◽  
Polygonum Type

Dovyalis caffra (Hook.f. Harv.) Hook.f. is a widespread and horticulturally important southern African endemic. Here described, ovule-to-seed development represents the first embryological information on this genus of the tribe Flacourtieae, Salicaceae  sensu lato. Results are discussed in the light of data available on the embryology of the order Malpighiales in general and on the tribe Flacourtieae in particular. It is clear that Dovyalis E.Mey. ex Am. shares many characters with other members of the Flacourtieae. Ovules of D. caffra are anatropous. bitegmic and crassinucellate with both bisporic Allium- and monosporic Polygonum-type embryo sacs. One of the most characteristic embryological features of the tribe is the pres­ence of an unusual, extranucellar embryo sac that stretches halfway up into the micropyle. Since this extraordinary-shaped embryo sac also defines the embryo sacs of Salix L. and Populus L., it is suggested that the character provides strong sup­port for the proposed close phylogenetic link between tribes Flacourtieae and Saliceae of Salicaceae sensu lato.

scholarly journals The dyad gene is required for progression through female meiosis in Arabidopsis

Development ◽  
2000 ◽  
Vol 127 (1) ◽  
pp. 197-207 ◽  
Author(s):  
I. Siddiqi ◽  
G. Ganesh ◽  
U. Grossniklaus ◽  
V. Subbiah
Keyword(s):  
Mother Cell ◽  
Megaspore Mother Cell ◽  
Female Gametophyte ◽  
Molecular Mechanisms ◽  
Higher Plants ◽  
Embryo Sac ◽  
Initial Step ◽  
Female Meiosis ◽  
Female Germ Cell ◽  
Further Development

In higher plants the gametophyte consists of a gamete in association with a small number of haploid cells, specialized for sexual reproduction. The female gametophyte or embryo sac, is contained within the ovule and develops from a single cell, the megaspore which is formed by meiosis of the megaspore mother cell. The dyad mutant of Arabidopsis, described herein, represents a novel class among female sterile mutants in plants. dyad ovules contain two large cells in place of an embryo sac. The two cells represent the products of a single division of the megaspore mother cell followed by an arrest in further development of the megaspore. We addressed the question of whether the division of the megaspore mother cell in the mutant was meiotic or mitotic by examining the expression of two markers that are normally expressed in the megaspore mother cell during meiosis. Our observations indicate that in dyad, the megaspore mother cell enters but fails to complete meiosis, arresting at the end of meiosis 1 in the majority of ovules. This was corroborated by a direct observation of chromosome segregation during division of the megaspore mother cell, showing that the division is a reductional and not an equational one. In a minority of dyad ovules, the megaspore mother cell does not divide. Pollen development and male fertility in the mutant is normal, as is the rest of the ovule that surrounds the female gametophyte. The embryo sac is also shown to have an influence on the nucellus in wild type. The dyad mutation therefore specifically affects a function that is required in the female germ cell precursor for meiosis. The identification and analysis of mutants specifically affecting female meiosis is an initial step in understanding the molecular mechanisms underlying early events in the pathway of female reproductive development.

Embryo sac development in some South African Lantana species (Verbenaceae)

Bothalia ◽  
1984 ◽  
Vol 15 (1/2) ◽  
pp. 161-166 ◽  
Author(s):  
J. J. Spies
Keyword(s):  
South African ◽  
Embryo Sac ◽  
Lantana Camara ◽  
The South ◽  
Polygonum Type ◽  
Embryo Sac Development ◽  
Chalazal Megaspore

Evidence that the South African Lantana camara L. complex only produces sexual embryo sacs is provided. It is shown that the archesporium occasionally divides mitotically and that both archesporia form tetrads. The chalazal megaspore of one tetrad and the micropylar megaspore of the second tetrad develop into Polygonum type embryo sacs. L. rugosa Thunb. also forms Polygonum type embryo sacs. The L. rugosa embryo sac has a much more densely packed cytoplasm, smaller vacuole and the position of the polar nuclei differs from that of the L. camara embryo sac. It is possible to distinguish between  L. camara and  L. rugosa on their embryo sac morphology alone.

Studies on the relationships and evolution of supraspecific taxa utilizing developmental data. 1. Stipa lemmonii (Gramineae)

1972 ◽  
Vol 50 (11) ◽  
pp. 2327-2352 ◽  
Author(s):  
Jack Maze ◽  
Lesley R. Bohm ◽  
Charles E. Beil
Keyword(s):  
Individual Differences ◽  
Pollen Tube ◽  
Early Development ◽  
Apical Meristem ◽  
Embryo Sac ◽  
Complex Structures ◽  
Plant Structure ◽  
Polygonum Type ◽  
The Individual ◽  
Developmental Features

This is a study of floret development and embryology of Stipa lemmonii (Vasey) Scribn. as a means of assessing its relationships and evolution. There is an advantage to using developmental data for it allows one to break complex structures down into developmental units. These developmental units can be compared and thus more characters can be analyzed. The lemma, palea, ventral lodicule, and carpel of S. lemmonii are leaf-like (sensu Sattler 1966, 1967) in initiation and early development. The stamens are stem-like and the ovule develops from the floret apical meristem. The ovule is interpreted as being cauline. The ovule is hemianatropous and pseudocrassinucellate. The inner integument delimits the micropyle. The integuments are ephemeral except for the inner layer of the inner integument. Embryo sac development is Polygonum type. Both synergids undergo change before entry of the pollen tube and the pollen tube appears to empty into the larger synergid. The antipodals are proliferated. The endosperm is at first free nuclear. Developmental features of S. lemmonii were compared with developmental features of S. tortilis, Oryzopsis miliacea, and S. hendersonii. The last is a species which hybridizes with S. lemmonii. Thirty-five characters were abstracted from the developmental data and were analyzed statistically. The results indicated that S. lemmonii and S. hendersonii are most closely related, and that these two plus S. tortilis form a group distinct from O. miliacea. The individual differences between taxa show gradation in the degree of difference. This is taken to indicate that the evolution of differences, and the evolution of taxa, is the result of the accumulation of many minor differences. Developmentally, plants are very simple, especially as compared with higher animals. Because of this, it is difficult to make generalizations about the "basic nature" of a plant structure using developmental data. Flowers seem best interpreted as functional units. This allows one to accept the concept that flowers in general are polyphyletic, a concept that is indicated by objective analysis of the data.

Embryology of Macroptilium arenarium (Leguminosae)

2006 ◽  
Vol 54 (6) ◽  
pp. 531 ◽  
Author(s):  
M. Gotelli ◽  
B. Galati ◽  
P. Hoc
Keyword(s):  
Comparative Study ◽  
Sexual Reproduction ◽  
Embryo Sac ◽  
Pollen Grains ◽  
Linear Arrangement ◽  
Polygonum Type ◽  
Chalazal Megaspore ◽  
Chasmogamous Flowers

Macroptilium arenarium (Bacigalupo) S.I.Drewes & R.A.Palacios produces two floral morphs, aerial chasmogamous flowers and cleistogamous flowers in geophyte racemes. A comparative study of the sporogenesis, gametogenesis and the development of the related sporophytic structures in both floral morphs is reported. The anther is tetrasporangiate, its wall consists of epidermis, endothecium, one or two middle layers and an uninucleate secretory tapetum. The mature endothecium presents fibrilar thickenings that are more developed in cleistogamous flowers. Pollen grains are tricolporate, angulaperturate, and are shed at bicellular stage. The ovule is crassinucelate, bitegmic and anacampylotropous. Megaspore tetrads with linear arrangement have been observed in chasmogamous flowers, whereas only megaspore dyads have been found in cleistogamous flowers. In both floral morphs the chalazal megaspore develops into an embryo sac of Polygonum type. Apomixis is considered as a possible replacement for sexual reproduction in cleistogamous flowers.

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