scholarly journals Number of Pollen Grains in Rice Cultivars with Different Cool-Weather Resistance at the Young Microspore Stage

2000 ◽  
Vol 3 (3) ◽  
pp. 299-305 ◽  
Author(s):  
Teiji Nakamura ◽  
Masahiro Chiba ◽  
Setsuo Koike ◽  
Iwao Nishiyama
Keyword(s):  
Pollen Grains ◽  
Rice Cultivars ◽  
Weather Resistance ◽  
Microspore Stage

Development of sperm cells in barley

1975 ◽  
Vol 53 (10) ◽  
pp. 1051-1062 ◽  
Author(s):  
David D. Cass ◽  
Ilana Karas
Keyword(s):  
Cell Membrane ◽  
Vegetative Cell ◽  
Generative Cell ◽  
Pollen Grains ◽  
Complete Separation ◽  
Pollen Wall ◽  
Vegetative Nucleus ◽  
Sperm Cells ◽  
Subsequent Stage ◽  
Microspore Stage

Ultrastructural events in barley sperm development were examined from the uninucleate microspore stage to establishment of two mature sperm cells in pollen grains. Microspore mitosis produces a vegetative nucleus and a naked generative cell, both embedded in vegetative cell cytoplasm. The generative cell membrane is enclosed by vegetative cell membrane. The generative cell, at first apparently unattached, becomes attached to the pollen wall and acquires a cell wall by centripetal vesicle accumulation. Wall formation may be complete at the time of generative cell karyokinesis; karyokinesis occurs while the generative cell is attached to the pollen wall. Cytokinesis of the generative cell is delayed. The subsequent stage is a binucleate, attached generative cell with a wall. Generative cell cytokinesis appears to involve formation of a partition between the two sperm nuclei. Eventual complete separation of the sperm cells occurs only after the two-celled derivative of the generative cell detaches from the pollen wall. Final stages in sperm cell separation are considered to result from degradation of the partitioning and surrounding wall, not from furrowing of a naked binucleate generative cell according to previous suggestions. Mature plastids were not observed in the generative cell or the sperms.

scholarly journals A Cytological Study of Anther and Pollen Development in Chinquapin (Castanea henryi)

HortScience ◽  
2020 ◽  
Vol 55 (6) ◽  
pp. 945-950
Author(s):  
Weiping Zhong ◽  
Zhoujun Zhu ◽  
Fen Ouyang ◽  
Qi Qiu ◽  
Xiaoming Fan ◽  
...  
Keyword(s):  
Pollen Development ◽  
Lipid Droplets ◽  
Morphological Characteristics ◽  
Pollen Grains ◽  
Middle Layer ◽  
Anther Development ◽  
Mature Pollen ◽  
Anther Wall ◽  
Male Flowers ◽  
Microspore Stage

The normal development of anthers and the formation of functional pollen are the prerequisites for successful pollination and fertilization. In this study, we observed dynamic changes in inflorescence and anther development in the chinquapin (Castanea henryi) using stereomicroscopy, light microscopy, and transmission electron microscopy. We found that cytokinesis during meiosis in microsporocytes was of the simultaneous type, and that the tetrads were mainly tetrahedral. Mature pollen grains contained two cells with three germ pores. The anther wall was of the basic type and composed of epidermis, endothecium, middle layers, and tapetum. Mature anthers had no middle layer and tapetum. The tapetum was of the glandular type. At the early microspore stage, a large number of starch granules appeared in the endothecium, which was deformed at the late microspore stage. Lipid droplets appeared in tapetum during the early microspore stage, and a few lipid droplets were still found during tapetum degeneration. The mature pollen accumulated a large amount of starch and lipids. These findings demonstrated that the anther wall provides nutrients and protection for pollen development. There is relatively stable correspondence between the external morphological characteristics of male flowers and internal structure of anther development.

scholarly journals Cytochemical and ultrastructural observations of anthers and pollen grains in Lathyrus undulatus Boiss

2011 ◽  
Vol 70 (1) ◽  
pp. 53-64 ◽  
Author(s):  
Filiz Vardar ◽  
Meral Ünal
Keyword(s):  
Morphological Characteristics ◽  
Pollen Grains ◽  
Middle Layer ◽  
Mature Pollen ◽  
Anther Wall ◽  
Tapetal Cells ◽  
Microspore Stage ◽  
Pollen Stage ◽  
Mature Anther ◽  
Insoluble Polysaccharides

Cytochemical and ultrastructural observations of anthers and pollen grains inLathyrus undulatusBoissInLathyrus undulatusBoiss. (Fabaceae), the young microspore stage of anther development was characterized by the enlarged secretory tapetal cells, which presented an intense reaction with regard to protein, insoluble polysaccharides and lipids. At bicellular pollen stage, the middle layer and the tapetum degenerated. After degradation of the tapetum, epidermis and single row U-shaped endothecium existed in the mature anther wall, and pollen grains remained in the locus. Young microspores had a spherical and centrally located nucleus with one or two nucleoli, many spherical lipid bodies and starchy plastids. A mature pollen grain contains insoluble polysaccharides, proteins, lipids and calcium. The mature pollen had the following morphological characteristics: 3-zonocolporate, prolate, tectate (imperforate) type of exine and perforate type of structure. The intine formed an important constituent portion of the wall, and consisted two sublayers: an outer intine (exintine) and an inner intine (endintine). The well-defined exine was made up of lipoidal substances and protein, but the intine composed of insoluble polysaccharides and protein. The bicellular state of the pollen grains persisted to anthesis.

scholarly journals Studies on the androgenesis in cultured anthers of Atropa belladonna L.

2015 ◽  
Vol 42 (2) ◽  
pp. 309-322 ◽  
Author(s):  
E. Misiura ◽  
M. Zenkteler
Keyword(s):  
Pollen Grains ◽  
Meiotic Abnormalities ◽  
Atropa Belladonna ◽  
Natural Conditions ◽  
Storage Materials ◽  
Skoog Medium ◽  
Microspore Stage ◽  
Androgenic Embryos ◽  
Meiosis I

Embryological investigations were carried out on developing anthers of <i>Atropa belladonna</i> grown in natural conditions and on anthers which produced androgenic embryos in the <i>in vitro</i> culture. The anatomy of developing anthers was analized in details. Meiotic abnormalities were not detected and 36 bivalents were present at metaphase of meiosis I. About 90% of pollen grains were normally developed. Anthers inoculated at the tetrad or microspore stage and cultured on Linsmaier and Skoog medium with kinetin 4 mg/1 and IAA - 2 mg/1 produced androgenic embryos. Differences in the development of septum, in the morphology of pollen grains, formation of tapetum, development of proembryos and the occurrence of storage materials were recorded. The origin of autopoliploid plants from haploid cells is discussed.

scholarly journals Calcium Distribution during Anther Development in Oil Tea (Camellia oleifera Abel.)

2015 ◽  
Vol 140 (1) ◽  
pp. 88-93 ◽  
Author(s):  
Dongmei Wei ◽  
Chao Gao ◽  
Deyi Yuan
Keyword(s):  
Plasma Membranes ◽  
Pollen Grains ◽  
Anther Development ◽  
Camellia Oleifera ◽  
Calcium Distribution ◽  
Temporal Features ◽  
Tapetal Cells ◽  
Microspore Stage ◽  
Mother Cells ◽  
The Relationship

The mechanism by which calcium regulates anther development remains unclear. This study investigated the relationship between calcium distribution and anther development in oil tea (Camellia oleifera Abel.) by using the potassium antimonite technique. Before the onset of microsporogenesis, abundant minute calcium precipitates appeared on the plasma membranes of microspore mother cells. Meanwhile, numerous precipitates accumulated in the tapetal cells. After meiosis, calcium precipitates appeared in young microspores. During microspore development, calcium precipitates mainly appeared in the small vacuoles of the cytoplasm. At the late microspore stage, a large vacuole formed, and the number of precipitates in the microspore decreased. The number of precipitates in the tapetal cells decreased as microsporogenesis proceeded. Then, calcium precipitates in the bicellular pollen cytoplasm again increased in number. During bicellular pollen development, the number of calcium precipitates decreased. As the pollen grains matured, only a few calcium precipitates were evident in the pollen cytoplasm. The results of this study, which show the spatial and temporal features of calcium distribution during the anther development of C. oleifera, suggest that calcium distribution is related to anther development.

scholarly journals In vivo and in vitro pollen maturation in Lilium: influence of carbohydrates

2014 ◽  
Vol 65 (1-2) ◽  
pp. 73-82 ◽  
Author(s):  
Christophe Clement ◽  
Daniel Al-Awad ◽  
Jean C. Audran
Keyword(s):  
Germination Rate ◽  
Starch Synthesis ◽  
Pollen Grains ◽  
Second Phase ◽  
Flower Buds ◽  
Flower Bud ◽  
Pollen Maturation ◽  
Microspore Stage

The purpose of this study was to develop a protocol for <em>in vitro</em> conform pollen maturation, as a model to study the involvement of carbohydrates on pollen maturation in <em>Lilium</em>. <em>In vivo</em> and <em>in vitro</em> pollen maturations were followed and compared by transmission electron microscopy, and several <em>in vitro</em> parameters were tested in terms of carbohydrate physiology. <em>In vivo</em>, pollen maturation was initiated at the vacuolated microspore stage, and consisted of two successive phases. The first phase was characterized by reactivation of microspore organelles, followed by microspore mitosis, starch synthesis and vacuole breakdown. During the second phase, starch was progressively degraded whereas lipid and phytine reserves accumulated. <em>In vivo</em>, pollen maturation occured within 14 days and pollen germination rate was 73.6 ± 2.2%. We then attempted to realise <em>in vitro</em> pollen maturation starting from the vacuolated microspore stage. The best results were obtained with flower buds cultivated at 26<sup>o</sup>C, in 100 µmol/m<sup>2</sup>/s light, with a 16h/8h photoperiod on a modified Heller's medium supplemented with NAA (10<sup>-2</sup> mg/l) and sucrose (M/6). In these conditions, pollen maturation occured within 7 days only. <em>In vitro</em> matured pollen is cytologically comparable to <em>in vivo</em> developed pollen grains and the germination rate was 72.4 ± 3.7%. When flower buds were cultivated in the dark, the germination rate decreased, but this could be compensated by providing high sucrose concentrations (1M) in the medium. Further, photosynthesis inhibitors had the same effect on pollen maturation than the darkness, strongly suggesting that photosynthesis occurs in the flower bud and is important for pollen maturation in <em>Lilium</em>.

Development of Cucurbita pepo pollen: ultrastructure and histochemistry of the sporoderm

1995 ◽  
Vol 73 (7) ◽  
pp. 1046-1057 ◽  
Author(s):  
M. Nepi ◽  
F. Ciampolini ◽  
E. Pacini
Keyword(s):  
Key Words ◽  
Cucurbita Pepo ◽  
Pollen Grains ◽  
Mature Pollen ◽  
Pollen Ultrastructure ◽  
Protein Layer ◽  
Tetrad Stage ◽  
Sporoderm Development ◽  
Pore Area ◽  
Microspore Stage

Sporoderm development is described in Cucurbita pepo, a species characterized by large spinous pollen grains covered by pollenkitt; i.e. the degeneration product of the tapetum. During the tetrad stage, separate types of primexine are observed for microspines and macrospines. At maturity these spines are affected differently by acetolysis: microspines contain polysaccharides as well as sporopollenin, and macrospine contain only sporopollenin. Unlike other species investigated so far, the intine begins to form at the early microspore stage and is very complex in the pore area where it forms a Zwischenkörper. The pore is covered by a protein layer of sporophytic origin and by the operculum. Just before anther opening, the pore protrudes, exposing part of the poral intine. Mature pollen has a thin callosic wall. The findings are discussed in the light of the fact that Cucurbita pepo pollen does not dehydrate prior to anthesis. Key words: Cucurbita pepo, pollen, sporoderm, exine, intine, sporophytic proteins.

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