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.

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.

Floral morphology and the development of gamethophytes in Eucalyptus melliodora A. Cunn

1968 ◽  
Vol 16 (1) ◽  
pp. 19 ◽  
Author(s):  
GL Davis
Keyword(s):  
Soviet Union ◽  
Floral Morphology ◽  
Embryo Sac ◽  
Pollen Grains ◽  
The Black Sea ◽  
Anther Wall ◽  
Polygonum Type ◽  
Threefold Increase ◽  
The Soviet Union ◽  
Sea Area

Flower buds are first recognizable in late December at the commencement of new growth, and the deciduous bracts enclosing each cyme are shed about 3 weeks later. The buds increase rapidly in size, but anthesis does not occur until the end of September and the seeds are not shed from the capsules until the following August. The development of the double operculum and the floral parts is traced. Archesporal tissue is differentiated in the anthers in late February but ovule primordia are not formed until the end of March, by which time the stamens have reached their full size and anther wall formation is well advanced. In each bud events in the anthers and ovules are broadly comparable, but variation in the stages of development occurs between buds on the same branch. Meiosis takes place during the winter months, and embryo sac development follows the Polygonum type. The components of the egg apparatus undergo a threefold increase in size after their formation and, whereas the egg contains little cytoplasm, the synergids become densely cytoplasmic and laterally hooked. The pollen grains are two-celled when they are shed through the slits at the apices of the anthers. A comparison is made of the embryology of E. melliodora and that of species cultivated in Italy and the Black Sea area of the Soviet Union.

scholarly journals A Contribution to the Embryology of Rhynchelytrum repens (Willd) C.E. Hubbard

1970 ◽  
Vol 7 (7) ◽  
pp. 37-40 ◽  
Author(s):  
Mohammed Inamuddin ◽  
Beatrice Were ◽  
Mohammad Saquib
Keyword(s):  
Mother Cell ◽  
Female Gametophyte ◽  
Pollen Grains ◽  
Middle Layer ◽  
Microspore Mother Cell ◽  
Polygonum Type ◽  
Dense Cytoplasm ◽  
Scientific World ◽  
Tapetal Cells ◽  
Functional Megaspore

The present investigation deals with morphological and embryological studies of Rhynchelytrum repens (Willd) C.E. Hubbard. The development of anther walls are found to be Monocotyledonous type. The tapetal cells are substantially large, glandular and uninucleate. The middle layer is ephemeral and their cells are small in size. It is sandwiched between endothecial and tapetal layer. The endothecial cells are large and develop fibrous thickenings. The microspore mother cell undergoes two successive reduction divisions, giving rise to isobilateral microspore tetrad. The tetrad separates and give rise to four pollen grains. Occasionally, the anther show degenerating pollen grains before dehiscence. Formation of Ubisch's bodies has also been observed. The pollen grains shed at three celled stage. The exine is thick while intine is thin. The ovule is anatropous, bitegmic and crassinucellate. The female archesporial cell becomes large with dense cytoplasm. It directly functions as megaspore mother cell and undergoes two meiotic divisions to produce a linear megaspore tetrad. The micropylar three cells degenerate and chalazal one becomes functional. The chalazal functional megaspore undergoes three mitotic divisions without wall formation and produces 8-nucleate embryosac. Such 8-nucleate embryosac organizes into Polygonum type of embryosac. It is interesting to note that some somatic cells of the ovule undergo nuclear divisions and give rise to facultative apomictic embryosacs. Key Words: Eldoret; Microsporangium; Ubisch's bodies; Facultative apomixis; Female gametophyte. DOI: 10.3126/sw.v7i7.3822 Scientific World Vol.7(7) 2009 pp.37-40

scholarly journals Embryology and fertility of the natural tetraploid Lessingianthus plantaginoides (Asteraceae, Vernonieae): taxonomic implications

Rodriguésia ◽  
2021 ◽  
Vol 72 ◽  
Author(s):  
Yanina de Jesús Pérez ◽  
Maria Betiana Angulo ◽  
Ana Honfi ◽  
Massimiliano Dematteis
Keyword(s):  
Embryo Sac ◽  
Pollen Grains ◽  
Anther Wall ◽  
Meiotic Analysis ◽  
Polygonum Type ◽  
Male And Female ◽  
Ontogenetic Study ◽  
Colonization Potential ◽  
Taxonomic Implications ◽  
Anther Wall Development

Abstract Lessingianthus plantaginoides (Vernonieae, Asteraceae) is a small natural tetraploid shrub that inhabits rocky highlands from South America. The population studied inhabits and covers an extensive region of a private reserve with high local biodiversity and animal and plant endemisms. With the purpose of providing insights into the cyto-embryology of this tetraploid species, the aims of this study were: to perform an ontogenetic study of the male and female gametophytes of L. plantaginoides; to carry out detailed meiotic analysis and evaluate the fertility of this species; to document and provide highlights on taxonomic implications of their reproductive aspects. Lessingianthus plantaginoides presented the following male and female gametophyte traits: dicotyledonous type of anther wall development, tetrahedral tetrads, 3-celled mature pollen grains; development of the chalazal megaspore, monosporic embryo sac and Polygonum type of megagametophyte development. The meiotic behavior was regular, the spores were tetrads of equal size and the pollen grains were highly stainable. Lessingianthus plantaginoides is a highly diplodized autotetraploid that reproduces sexually and has high meiotic regularity; which is apparently responsible for its colonization potential. It now seems certain that polyploid speciation plays a significant role in the establishment and diversification of the genus.

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.

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.

Floral morphology, embryology, and relationships of the Berberidaceae.

1969 ◽  
Vol 17 (1) ◽  
pp. 69 ◽  
Author(s):  
RLN Sastri
Keyword(s):  
Floral Morphology ◽  
Embryo Sac ◽  
Pollen Grains ◽  
Wall Layer ◽  
Vascular Supply ◽  
Anther Wall ◽  
Polygonum Type ◽  
Innermost Layer ◽  
Secretory Type ◽  
Mother Cells

The floral morphology and development of the gametophytes in Berberis umbellata and Mahonia leschenaultii have been studied. All the perianth members have three traces each in B. umbellata while in M. leschenaultii the members of the outer three whorls have five veins each and those of the fourth three veins each. The vascular supply for the inner two whorls of perianth and the stamens arises as conjoint traces. The wall of the gynoecium is traversed by numerous bundles with some concentrated in the placental region. The dorsal and ventral bundles are differentiated in M. leschenaultii but not in B. umbellata. The tricarpellary interpretation of the gynoecium is shown to be unconvincing. The gynoecium is regarded as monocarpellary. The mature anther wall is five-layered including the epidermis, of which the innermost layer forms the tapetum of secretory type. The tapetal cells are four to eight-nucleate. The hypodermal wall layer develops into a fibrous endothecium in M. leschenaultii. In B. urnbellata, the endothecium develops U-shaped thickenings. Division of pollen mother cells is successive. Pollen tetrads are usually isobilateral. Mature pollen grains are three-colpate and two-celled. The ovule is anatropous, bitegmic, and crassinucellate. In B. umbellata, a rudimentary aril is formed as an outgrowth of the funiculus. The single hypodermal archesporial cell in the young ovule cuts off a parietal cell. Development of the embryo sac is of the Polygonum type. The synergids show filiform apparatus and are persistent. The antipodals are large and persistent in M. leschenaultii and ephemeral in B. umbellata. The relationships of the Berberidaceae (sensu Hutchinson 1959) to the Menispermaceae, Lardizabalaceae, and the Ranunculaceae (sensu lato) are discussed.

Reproductive development in two species of Darwinia Rudge (Myrtaceae)

1969 ◽  
Vol 17 (2) ◽  
pp. 215 ◽  
Author(s):  
N Prakash
Keyword(s):  
Embryo Sac ◽  
Pollen Grains ◽  
Reproductive Development ◽  
Outer Zone ◽  
Mature Embryo ◽  
Globular Embryo ◽  
Primary Endosperm Nucleus ◽  
Oil Glands ◽  
Polygonum Type ◽  
History Of

In Darwinia the floral parts are differentiated in a "calyx-orolla-gynoeciumandroecium" sequence. In individual buds stages of microsporogenesis markedly precede corresponding stages of megasporogenesis. The anther is tetrasporangiate with all sporangia lying in one plane. The secretory tapetum is one- to three-layered within the same microsporangium and a large number of Ubisch bodies are formed. The anthers dehisce by minute lateral pores and an ingenious mechanism helps disperse the twocelled pollen grains. A basal placenta in the single loculus of the ovary bears four ovules in D. micropetala and two in D. fascicularis. In both species, however, only one ovule is functional after fertilization. The fully grown ovules are anatropous, crassinucellar, and bitegmic; the inner integument forms the micropyle. The parietal tissue is most massive at the completion of megasporogenesis but is progressively destroyed later. The embryo sac follows the Polygonum type of developnlent and when mature is five-nucleate, the three antipodals being ephemeral. Following fertilization, the primary endosperm nucleus divides before the zygote. Subsequent nuclear divisions in the endosperm mother cell are synchronous and lead to a free-nuclear endosperm which becomes secondarily cellular, starting from the micropylar end at the time the globular embryo assumes an elongated shape. Embryogeny is irregular and the mature embryo is straight with a massive radicle and a hypocotyl which terminates in two barely recognizable cotyledons. Sometimes the minute cotyledons are borne on a narrow neck-like extension of the hypocotyl. A suspensor is absent. Both integuments are represented in the seed coat and only the outer layer of the outer and the inner layer of the inner integuments, with their thick-walled tanniniferous cells, remain in the fully grown seed. The ovary wall is demarcated into an outer zone containing oil glands surrounded by cells containing a tannin-like substance and an inner zone of spongy parenchyma. In the fruit this spongy zone breaks down completely but the outer zone is retained. The two species of Darwinia, while closely resembling each other in their embryology, differ significantly from other Myrtaceae. However, no taxonomic conclusions are drawn at this stage, pending enquiry into the life history of other members of the tribe Chamaelaucieae.

scholarly journals Dynamics of Polysaccharides and Neutral Lipids during Anther Development in Castor (Ricinus communis)

2015 ◽  
Vol 140 (4) ◽  
pp. 356-361 ◽  
Author(s):  
Dongmei Wei ◽  
Huimin Xu ◽  
Ruili Li
Keyword(s):  
Neutral Lipids ◽  
Ricinus Communis ◽  
Starch Content ◽  
Single Layer ◽  
Pollen Grains ◽  
Middle Layer ◽  
Anther Development ◽  
Anther Wall ◽  
Starch Grains ◽  
Tapetal Cells

Anthers contain starch and neutral lipids, which have key roles in microspore ontogeny and gametophyte development. In this study, we observed the dynamic changes in starch and neutral lipids in the anther developmental processes of castor (Ricinus communis) by cytochemical methods. Starch grains and neutral lipids presented a regular dynamic distribution during anther development. In young anthers, some neutral lipids accumulated in sporogenous cells, whereas neutral lipids disappeared with microspore growth. At the late microspore stage, starch grains began to accumulate in microspores, and the starch content of bicellular pollen significantly increased after microspore mitosis. At anthesis, starch grains and neutral lipids accumulated in the mature pollen grains. Visible changes occurred in anther wall cells. The epidermis, middle layer, and tapetum were degenerated, and only a single layer of endothecium remained at anthesis. The dynamic variation of starch grains and neutral lipids in tapetal cells was consistent with the changes in microspores and pollen during anther development. All these findings demonstrated that tapetal cells directly interacted with the developing gametophytes. The tapetal cells play an important role in supplying nutritional substances for microspore absorption. Moreover, the endothecium protects the pollen and contributes to anther dehiscence. The results of this study provide a foundation for the further research on sexual reproduction in angiosperms.

The floral morphology and embryology of Themeda australis (R. Br.) Stapf

1964 ◽  
Vol 12 (2) ◽  
pp. 157 ◽  
Author(s):  
PS Woodland
Keyword(s):  
Embryo Sac ◽  
Pollen Grains ◽  
Low Fertility ◽  
Linear Tetrad ◽  
Polygonum Type ◽  
Morphological Variations ◽  
Endosperm Formation ◽  
Secretory Type ◽  
Successive Cytokinesis ◽  
Mother Cells

A comparative study was carried out between diploid and tetraploid races of Themeda australis from Armidale and Cobar, respectively. Some morphological variations occur in both populations, but sporogenesis and gametogenesis are identical. The anther is tetrasporangiate and the development of its four-layered wall is described. The tapetum is of the secretory type and its cells become binucleate at the initiation of meiosis in the adjacent microspore mother cells which undergo successive cytokinesis. Microspore tetrads are usually isobilateral and the pollen grains are three-celled at dehiscence, which takes place by lateral longitudinal slits. The ovule is of a modified anatropous form and bitegmic, the broad micropyle being formed of both integuments. The single hypodermal archesporial cell develops directly into the megaspore mother cell and the nucellar epidermis undergoes periclinal and anticlinal divisions to form a conspicuous epistase. The chalaza1 megaspore of the linear tetrad gives rise to a Polygonum-type embryo sac. Material from the Armidale population showed one embryo sac per ovule, but two to five embryo sacs were present in that from Cobar. Embryogeny is typically graminaceous and endosperm formation is at first free-nuclear, later becoming cellular. Polyembryony follows fertilization of several embryo sacs within the same ovule. The reasons for low fertility of T. australis and poor germination of seeds are discussed.

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