Megasporogenesis and microsporogenesis in Vicia faba

1975 ◽  
Vol 53 (23) ◽  
pp. 2804-2812 ◽  
Author(s):  
John P. Mitchell
Keyword(s):  
Vicia Faba ◽  
Mother Cell ◽  
Megaspore Mother Cell ◽  
Apical Cell ◽  
Outer Integument ◽  
Spore Wall ◽  
Early Prophase ◽  
Prophase I ◽  
Classic Pattern ◽  
Mother Cells

A multicellular archesporium develops beneath two layers of cells in the young ovules of Vicia faba L. The megaspore mother cell differentiates from the apical cell of this archesporial group. A linear array of megaspores results from a normal meiosis. The inner integument is initiated by periclinal divisions in a ring of two ovule epidermal cells while the outer integument arises as a bump at the base of the ovule. Integument development starts while the megaspore mother cell is in early prophase I. The megaspore second from the chalazal end is the functional megaspore. In the anthers, meiosis in the microsporocytes is initiated before meiosis in the megaspore mother cells and follows the classic pattern. The tapetum becomes progressively more distinct during early prophase I. The nuclei complete several DNA replications without dividing. The tapetum finally disintegrates after the uninucleate microspore goes through mitosis. Endothecium development is apparent accompanying the elongation of the newly formed isodiametric microspores, as is the formation of the complex spore wall architecture.

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.

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.

scholarly journals Meiotic Chromosome Behavior and Capsule Setting in Doritaenopsis Hybrids

2008 ◽  
Vol 133 (1) ◽  
pp. 107-116 ◽  
Author(s):  
Pablo Bolaños-Villegas ◽  
Shih-Wen Chin ◽  
Fure-Chyi Chen
Keyword(s):  
Cell Division ◽  
Pollen Mother Cell ◽  
Chromosome Pairing ◽  
Chromosomal Aberrations ◽  
High Frequency ◽  
Mother Cell ◽  
Seed Set ◽  
Pollen Viability ◽  
High Pollen ◽  
Mother Cells

The development of new cultivars in Doritaenopsis Guillaum. & Lami orchids is often hindered by factors such as low seed count in hybrids. Cytological study may offer the ability to develop new hybrids by revealing cultivars with good chromosome pairing and high pollen viability, which are somewhat difficult to obtain under current breeding programs. Cross pollination, pollen viability, and chromosomal behavior during meiosis were analyzed to reveal the relation between seed fertility and capsule set in Doritaenopsis hybrids. The number of mature capsules harvested and their relative seed content were used as indices of crossing availability. The results of meiosis were evaluated according to pollen viability detected by fluorescein diacetate and quantification of sporad types by acid fuchsin staining. Chromosome number and pairing at meiosis were observed in root tips or in samples of pollen mother cells. A positive relation was found among high seed set, high frequency of viable tetrads, high degree of chromosome pairing, and low frequency of chromosomal aberrations such as inversions and translocations. On the basis of these factors, three types of hybrids could be distinguished. In type one hybrids, chromosomes paired as bivalents, pollen mother cells divided into tetrads, and capsule setting occurred after pollination of pollen acceptors. In type two hybrids, chromosomes remained mainly as univalents that developed into micromeiocytes, pollen mother cell division was disrupted, and seed recovery was low after pollination. Type three hybrids showed chromosomes paired mostly as multivalents, chromosome bridges, pollen mother cell division with massive failure, and little fertility. In Doritaenopsis orchids, high pollen viability and high fertility depends on a high frequency of normal tetrads, and low seed set in cross-pollination is predicted with micronuclei in the end products of meiosis. The occurrence of chromosomal aberrations may suggest a process of genome differentiation that could compromise breeding efforts if not taken into consideration.

scholarly journals Epigenetic Regulation of Plant Gametophyte Development

2019 ◽  
Vol 20 (12) ◽  
pp. 3051 ◽  
Author(s):  
Vasily V. Ashapkin ◽  
Lyudmila I. Kutueva ◽  
Nadezhda I. Aleksandrushkina ◽  
Boris F. Vanyushin
Keyword(s):  
Mother Cell ◽  
Female Gametophyte ◽  
Male Gametophyte ◽  
Endosperm Development ◽  
Epigenetic Changes ◽  
Gametophyte Development ◽  
Daughter Cells ◽  
Second Stage ◽  
Somatic Tissues ◽  
Mother Cells

Unlike in animals, the reproductive lineage cells in plants differentiate from within somatic tissues late in development to produce a specific haploid generation of the life cycle—male and female gametophytes. In flowering plants, the male gametophyte develops within the anthers and the female gametophyte—within the ovule. Both gametophytes consist of only a few cells. There are two major stages of gametophyte development—meiotic and post-meiotic. In the first stage, sporocyte mother cells differentiate within the anther (pollen mother cell) and the ovule (megaspore mother cell). These sporocyte mother cells undergo two meiotic divisions to produce four haploid daughter cells—male spores (microspores) and female spores (megaspores). In the second stage, the haploid spore cells undergo few asymmetric haploid mitotic divisions to produce the 3-cell male or 7-cell female gametophyte. Both stages of gametophyte development involve extensive epigenetic reprogramming, including siRNA dependent changes in DNA methylation and chromatin restructuring. This intricate mosaic of epigenetic changes determines, to a great extent, embryo and endosperm development in the future sporophyte generation.

Female gametophyte and embryo development in western hemlock (Tsuga heterophylla)

1974 ◽  
Vol 52 (4) ◽  
pp. 885-893 ◽  
Author(s):  
Elizabeth A. Stanlake ◽  
John N. Owens
Keyword(s):  
Embryo Development ◽  
Mother Cell ◽  
Megaspore Mother Cell ◽  
Morphological Study ◽  
Female Gametophyte ◽  
Tsuga Heterophylla ◽  
Western Hemlock ◽  
Seed Fall

A morphological study of the female gametophyte and embryo development was made for western hemlock (Tsuga heterophylla (Raf.) Sarg.) growing in the Victoria, B.C., area. Western hemlock follows a pattern of development similar to other members of the Pinaceae. A comparison was also made between development in western hemlock and other gymnosperm families. Meiosis of the megaspore mother cell in western hemlock begins in early February and is completed at the end of the first week in March. This is 3 weeks before pollination. Fertilization occurs 6 weeks after pollination, in the middle of May. Embryo development takes place throughout June and July and the embryo is mature by the middle of August. Seed fall occurs throughout September, 5 months after pollination.

The temporal relationship between the development of intracellular hyphae and haustoria by Physopella zeae in Zea mays

1988 ◽  
Vol 66 (4) ◽  
pp. 742-744 ◽  
Author(s):  
Michèle C. Heath ◽  
M. R. Bonde
Keyword(s):  
Plant Cell ◽  
Mother Cell ◽  
Plant Cell Wall ◽  
Rust Fungus ◽  
Morphological Differentiation ◽  
Adjacent Cell ◽  
Previous Suggestion ◽  
Epidermal Tissue ◽  
Developmental Relationship ◽  
Mother Cells

To investigate the developmental relationship between haustoria and intracellular hyphae, fixed and cleared whole mounts of com leaves infected with the tropical corn rust fungus Physopella zeae (Mains) Cumm. & Ramachar were examined by interference contrast light microscopy. Haustoria were clearly distinguished from intracellular hyphae by their morphological differentiation into a filamentous body and a narrow neck. The latter was encircled by a thin neckband, which appeared to develop in young haustoria at the time when the haustorial body started to expand. Observations made at the colony margins suggested that the fungus grew into uninvaded epidermal tissue in the following sequence: (i) formation of a haustorium from a haustorial mother cell in an adjacent cell, (ii) formation of an intracellular hypha next to the haustorium by the same intracellular hypha that had formed the haustorial mother cell, (iii) growth of the intracellular hypha within the newly invaded plant cell, (iv) formation by the intracellular hyphae of haustorial mother cells against the plant cell wall adjacent to an uninvaded cell, and (v) formation of haustoria in the uninvaded cell. These results support the previous suggestion that the haustorium may induce a state of susceptibility in the plant cell, "paving the way" for invasion by the intracellular hyphae.

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