Über das Antherentapetum mit besonderer Berücksichtigung seiner Kernzahl
01 Feb 1954-Vol. 101, Iss: 1, pp 1-63
TL;DR: In der vorliegenden Arbeit wurden zur Prufung der jungst aufgeworfenen Frage, ob dem Vorkommen des einkernigen Tapetums eine gewisse systematischen Bedeutung zukame, nicht nur die Angaben uber das Einkernige Tapetum (vgl. die Zusammenstellung S. 15−17) kritisch gesichtet, sondern auch alle Angabens uber e
Abstract: Da in den letzten Jahren die Beobachtungen uber ein einkerniges Tapetum weiter zugenommen haben, liegt die Vermutung nahe, das dieses eine weitere Verbreitung hat, als bisher angenommen wurde. In der vorliegenden Arbeit wurden zur Prufung der jungst aufgeworfenen Frage, ob dem Vorkommen des einkernigen Tapetums eine gewisse systematische Bedeutung zukame, nicht nur die Angaben uber das einkernige Tapetum (vgl. die Zusammenstellung S. 15–17) kritisch gesichtet, sondern auch alle Angaben uber ein mehrkerniges Tapetum gesammelt und beide Vorkommen einander gegenubergestellt (vgl. den systematischen Teil). Es schien auch angezeigt, auf die verschiedenartigen Abweichungen von der normalen Tapetumentwicklung hinzuweisen, da in einzelnen solchen Fallen (bei weiblichen Pflanzen und pollensterilen Apomikten) ein Unterbleiben oder Verzogern von Kernteilungen in den Tapetumzellen beobachtet werden konnte, wodurch eine Einkernigkeit vorgetauscht sein kann. — Das Vorhandensein sowohl eines inneren als auch eines mehrschichtigen Tapetums ist in den vorliegenden Fallen nicht an eine bestimmte Kernzahl geknupft.
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TL;DR: A hypothetical phylogenesis of the tapetum is proposed on the basis of its morphological appearance and of the nutritional relations with meiocytes/spores, and the evolutionary trends of thetapeta tend towards a more and more intimate and increasingly greater contact with the spores/pollen grains.
Abstract: It appears that the tapetum is universally present in land plants, even though it is sometimes difficult to recognize, because it serves mostly as a tissue for meiocyte/spore nutrition. In addition to this main function, the tapetum has other functions, namely the production of the locular fluid, the production and release of callase, the conveying of P.A.S. positive material towards the loculus, the formation of exine precursors, viscin threads and orbicules (= Ubisch bodies), the production of sporophytic proteins and enzymes, and of pollenkitt/tryphine. Not all these functions are present in all land plants:Embryophyta. Two main tapetal types are usually distinguished in theSpermatophyta: the secretory or parietal type and the amoeboid or periplasmodial type; in lower groups, however, other types may be recognized, with greater or lesser differences. A hypothetical phylogenesis of the tapetum is proposed on the basis of its morphological appearance and of the nutritional relations with meiocytes/spores. The evolutionary trends of the tapeta tend towards a more and more intimate and increasingly greater contact with the spores/pollen grains. Three evolutionary trends can be recognized: 1) an intrusion of the tapetal cells between the spores, 2) a loss of tapetal cell walls, and 3) increasing nutrition through direct contact in narrow anthers.
346 citations
01 Jan 1984
TL;DR: After more than 30 years of research on the nuclear cytology of differentiated tissues, it is now clear that the “supernumerary chromonemal reproduction” at interphase, better called “chromosome endoreduplication” (Levan and Hauschka 1953), is the commonest and most widespread process of cell polyploidization in both plants and animals.
Abstract: In the older literature on angiosperm morphology many examples of very large cells with giant or “hypertrophied” nuclei within differentiated tissues, including reproductive tissues, have been reported, and the connection between nuclear size and trophic activity of the cell has been stressed (references in Schnarf 1929, Tischler 1944, Maheshwari 1950). Goldstein (1928) even attempted to establish a correlation between nuclear form and functional activities of normal and pathological cells. In the absence of adequate knowledge of the mechanisms responsible for the multiplication of the genome, the large size and the variable form (irregular, crenate, lobate, constricted, furrowed, etc.) of nuclei were generally assumed to result from fusion of nuclei and/or amitosis. The significance of restitutional mitosis as a mechanism of doubling the chromosome number was not realized, and was generally regarded as a pathological process. The situation began to change in the late 1930’s—early 1940’s following the discovery of endomitosis in Homoptera, e.g., the pondskaters of the genus Gerris (Geitler 1939), and the proposition that the tetraploid mitoses “with paired chromosomes” (now called “diplochromosomes”) in poly somatic root tips of Spinacia oleracea are due to a double chromosome reproduction at interphase (Berger 1941). After more than 30 years of research on the nuclear cytology of differentiated tissues, it is now clear that the “supernumerary chromonemal reproduction” at interphase (Lorz 1947), better called “chromosome endoreduplication” (Levan and Hauschka 1953), is the commonest and most widespread process of cell polyploidization in both plants and animals (Brodsky and Uryvaeva 1977, D’Amato 1977 a, Nagl 1978).
178 citations
TL;DR: This article is restricted to a summary, discussion and evaluation of the knowledge of the physiology and cytology of anther development, particularly the role of tapetum and the development of pollen grains.
Abstract: An understanding of the morphology and physiology of the angiosperm flower and its component parts is of considerable importance in programmes for the development of new agricultural and horticultural varieties, in the elucidation of various hereditary processes and their control, and for an insight into various problems of cell biology, cell division and the physiology and control of reproduction. A great deal of work has been produced since the days of Amici (1824) and Hofmeister (I 848) regarding the developmental aspects of reproductive parts of the angiosperm flower, fertilization and the development of endosperm and embryo leading to the formation of a mature seed. Much of this work is summarized in the books by Schnarf (1929, 1931), and Maheshwari (1950, 1963). Unfortunately, very little effort, if any, has been made to understand the physiology of the reproductive organs of the angiosperm flower, particularly the chemical and cytochemical changes involved in the initiation and control of these processes (Vasil, 1965). The ultrastructural studies made by Rosen, Gawlik, Dashek & Siegesmung (1964) and by Sassen (1964) of the pollen tubes, by Heslop-Harrison (1962, 1963b, 1964) of the developing anther, and by Jensen (1963) of the embryo sac, fertilization and embryogenesis are, therefore, especially welcome. Some work has also been done recently on the histochemical and biochemical aspects of reproduction in higher plants (Linskens, 1 9 6 4 ~ ) . In order to limit the field of discussion and because of my own interest and familiarity with the angiosperm anther, this article is restricted to a summary, discussion and evaluation of our knowledge of the physiology and cytology of anther development, particularly the role of tapetum and the development of pollen grains." Discussion of the various aspects of the physiology of pollen grains after dehiscence is excluded as
123 citations
111 citations
TL;DR: The distribution of tapetal types in basal angiosperms is reviewed both from the literature and new observations in the context of recent phylogenetic analyses, finding apparent plasticity for a relatively brief but critical time in angiosperm evolution.
Abstract: The distribution of tapetal types in basal angiosperms is reviewed both from the literature and new observations in the context of recent phylogenetic analyses. Secretory tapeta predominate among land plants. The majority of basal angiosperms share a secretory tapetum with their anthophyte ancestors. Plasmodial and invasive tapeta are relatively rare in eudicots but have evolved several times among early‐branching angiosperms, especially in monocotyledons, in which they have evolved three or more times. The invasive tapetum has evolved at least four other times independently in basal angiosperms: in Nymphaeaceae, Annonaceae, Monimiaceae, and Winteraceae. Plasmodial tapeta are mostly found in monocotyledons but have evolved at least twice in basal angiosperms, in Annonaceae, and in Hernandiaceae/Lauraceae. This apparent plasticity for a relatively brief but critical time in angiosperm evolution may reflect the early evolution of highly specific pollination syndromes.
82 citations
References
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TL;DR: The pistillate flower is strongly epigynous, and develops a long floral tube reaching from the sessile ovary to the surface of the water, which early develops a pouch in which the antipodal group of nuclei is formed.
Abstract: 1. The pistillate flower is strongly epigynous, and develops a long floral tube reaching from the sessile ovary to the surface of the water. 2. Four megaspores are usually formed; six were noted in one instance. 3. The embryo sac early develops a pouch in which the antipodal group of nuclei is formed. 4. The polars approach one another at an early stage and may remain for a long time side by side; their fusion, however, was not noted before fertilization. 5. The stamens regularly produce two sporangia each. The primary wall layer nearly invests the sporogenous tissue, which later may contribute to the tapetum on the axial side. 6. The pollen grains adhere in tetrads and have a greater specific gravity than water. The exine possesses spines which hold back the surface film and imprison sufficient air to keep the spores afloat. 7. The male cells are organized in the pollen grain and are joined together by their elongated ends. 8. Gas bubbles aid in detaching the staminate flowers and in bringing them prompt...
38 citations
TL;DR: Auf Grund vergleichender Untersuchungen in den Pollenmutterzellen und Tapetenzellen von geschlechtlich and apomiktisch sich fortpflanzendenHieracium-Arten gelangte man zu der Annahme, daß zwischen der Tapetumentartung and den auffallenden meiotischen Vorgängen in the PollenM
Abstract: 1.
Es sind 15 Arten der GattungHieracium zytologisch untersucht und ihre Chromosomenzahl aus der Kernteilung in den Pollenmutterzellen, wie aus den Zellen der Wurzelspitzen ermittelt worden. In manchen Pollenmutterzellen einzelner Pflanzen vonH. canadense ist dieBoreale- in anderen dieLevigatum-Meiosis beobachtet worden. Dieser Zustand findet sich auch beiH. vulgatum. Bei dieser Art kommen auserdem in manchen Pollenmutterzellen eine pseudohomootypische Kernteilung wie auch einepseudoillyricumahnliche Meiosis vor. BeiH. pulmonarioides wie beiH. echioides wurden Pollenmutterzellen mit Chromosomen beobachtet, die in den verschiedenen Zellen nicht gleiche Gestalt haben. So kommen z. B. Pollenmutterzellen mit langlichen, den somatischen ahnlichen Chromosomen und solche vor, die vollstandig rundlich aussehen, oder alle moglichen Ubergange dazwischen aufweisen.
2.
Auf Grund vergleichender Untersuchungen in den Pollenmutterzellen und Tapetenzellen von geschlechtlich und apomiktisch sich fortpflanzendenHieracium-Arten gelangte man zu der Annahme, das zwischen der Tapetumentartung und den auffallenden meiotischen Vorgangen in den Pollenmutterzellen der apomiktischen, Hieracien ein Zusammenhang bestehe.
3.
Bei 5 Arten der UntergattungArchieracium und bei einer Art der UntergattungPilosella ist die Embryosackentwicklung untersucht worden. Es wurde festgestellt, das manchmal beiH. murorum die erste Kernteilung in der Embryosackmutterzelle ahnlich der in den Pollenmutterzellen verlaufe. BeiH. vulgatum undH. ramosum sind Falle beobachtet worden, die auf gleichzeitiges Vorkommen von somatischer Parthenogenese und somatischer Apogamie hindeuten. Es sind z. B. in ein und demselben Embryosack Embryonen beobachtet worden, die aus der Eizelle, wie auch solche, die aus einer oder beiden Synergiden entstammten. Es sind Hinweise darauf vorhanden, das beiH. ramosum und vielleicht auch beiH. canadense eine apospore Entwicklung stattfinde. Es wurden zytologische Beweise erbracht, die das Vorkommen von nucellarer Polyembryonie wie auch von endospermaler Embryoentwicklung beiH. pilosella bestatigen.
38 citations
TL;DR: The inference seems justifiable that the mutations of O. Lamarckiana arise during the reduction divisions and that pollen grains which will give rise to mutants differ in their potentialities and probably also in chromatin morphology from the ordinary pollen grains of the plant.
Abstract: 1. Failure of pollen development in O. lata is not due to ingrowth of the tapetum to fill the loculus, as described by POHL, but to some other agency at work in the hybrid, the nature of which is not fully explained. 2. Pollen development in O. lata may proceed to the formation of tetrads, but degeneration of both mother cells and tapetum frequently begins in the resting stage or during the prophase of the first mitosis. 3. Heterochromosomes arise in O. lata in the prophase after synapsis. There may be one or two such bodies, which are formed as large rings by the cutting off of a portion of the spirem thread before the remainder breaks up into chromosomes. These bodies later are found in metaphase of the heterotypic mitosis, usually in the cytoplasm near the spindle. They do not divide, but become smaller and probably disappear at the end of the first mitosis. These bodies are also found in the O. Lamarckiana hybrid, in which they doubtless have the same origin. They probably represent discarded chromoso...
38 citations
38 citations
TL;DR: C Y T O L O G Y O F T H E P O L L E N .
37 citations