RESUMEN
Two original mechanisms of nuclear restitution related to different processes of meiotic division of pollen mother cells (PMCs) have been found in male meiosis of the lines of maize haploids no. 2903 and no. 2904. The first mechanism, which is characteristic of haploid no. 2903, consists in spindle deformation (bend) in the conventional metaphase-anaphase I. This leads to asymmetric incomplete cytokinesis with daughter cell membranes in the form of incisions on the mother cell membrane. As a result, the chromosomes of the daughter nuclei are combined into a common spindle during the second meiotic division, and a dyad of haploid microspores is formed at the tetrad stage. The frequency of this abnormality is about 50%. The second restitution mechanism, which has been observed in PMCs of haploid no. 2904, results from disturbance of the fusion of membrane vesicles (plastosomes) at the moment of formation of daughter cell membranes and completion of cytokinesis in the first meiotic division. This type of cell division yields a binuclear monad. In the second meiotic division, the chromosomes of the daughter nuclei form a common spindle, and meiosis results in a dyad of haploid microspores. The frequency of this abnormality is as high as 15%. As a result, haploid lines no. 2903 and no. 2904 partly restore fertility.
Asunto(s)
División del Núcleo Celular/genética , Citocinesis/fisiología , Meiosis/fisiología , Zea mays , Núcleo Celular/genética , Cromosomas de las Plantas/genética , Haploidia , Huso Acromático/genética , Zea mays/citología , Zea mays/genéticaRESUMEN
A group of new meiotic division abnormalities affecting processes of phragmoplast centrifugal movement in successive cytokinesis in cereal pollen mother cells is described. These phenotypes present new information about motile phragmoplast formation and operation and confirm our model of centrifugal movements as B-ana-phase modification.
Asunto(s)
Citocinesis/fisiología , Grano Comestible/fisiología , Meiosis/fisiología , Polen/fisiología , Grano Comestible/citología , Polen/citologíaRESUMEN
Previously non-described in literature abnormalities of phragmoplast formation in pollen mother cells of cereal haploids and allohaploids are reported. These abnormal phenotypes reveal and illustrate some steps of the process of phragmoplast formation in dividing plant cell, indicate a special regulation of their start, and confirm the information about the process obtained from other sources. The cytokinetic stage in plant cytoskeleton cycle is discussed.
Asunto(s)
Quimera/fisiología , Citocinesis/fisiología , Grano Comestible/fisiología , Meiosis/fisiología , Polen/fisiología , Grano Comestible/citología , Polen/citologíaRESUMEN
The paper describes the phenomenon of disorganization of completely formed subcellular structures: division spindle, phragmoplast and chromosome telophase groups. These structures disintegrate into their elements (cytoskeletal fibers, chromosomes) that transform into chaotic system. Chaotization of cytoskeleton structures such as prophase spindle in mitosis or perinuclear ring in meiosis is a normal step of wild type plant cell division. Disintegration of division spindle and phragmoplast presumably indicate the abnormality of temporal regulation of cytoskeleton cycle during meiosis. Disintegration of telophase chromosome groups and the migration of the chromosomes backward to the equatorial area might mean the abnormal start of some prometaphase mechanisms, in particular, chromokinesins activation.
Asunto(s)
Quimera/metabolismo , Cromosomas de las Plantas/metabolismo , Meiosis , Huso Acromático/metabolismo , Telofase , Triticum/metabolismo , Quimera/genética , Cromosomas de las Plantas/genética , Huso Acromático/genética , Triticum/genéticaRESUMEN
The phragmoplast dysfunction in wheat x rye hybrid F1 male meiosis has been described. The pollen mother cells (PMCs) show the phenotype where transition from central spindle fibers (forming a solid bundle) to a phragmoplast (hollow cylinder) is blocked. The blockade suppresses centrifugal movement of the phragmoplast and cell plate formation. The resulting cells occur to be binucleate. Sometimes, the two nuclei join and form one restitution nucleus. PMCs of wheat x rye F1 hybrid N D-144gp 06r. F1 (T. aestivum c. 93-60 T 9 x S. cereale c. Saratovskaya 7) showing this phenotype have an additional phragmoplast at late telophase. This happens like that in the case of immobile phragmoplast formation in meiosis in bicotyledons: the new phragmoplast arises by the aid of microtubules polymerization starting from the spindle poles. The new additional phragmoplast builds a new cell plate and accomplishes cytokinesis.
Asunto(s)
Citocinesis , Polen/citología , Secale/citología , Triticum/citología , Quimera/genética , Quimera/fisiología , Citoplasma/metabolismo , Citoesqueleto/metabolismo , Meiosis , Fenotipo , Polen/genética , Secale/genética , Triticum/genéticaRESUMEN
The deviation of prophase cytoskeletal ring formation was determined during meiotic division in 50% of pollen mother cells (PMCs) in maize haploid No 1498 (Zea mays). At prophase in both meiotic divisions the cytoskeletal ring is formed in cortical region of cytoplasm instead of perinuclear. Sometimes formation of both perinuclear and cortical rings is observed in the same cell. It has been shown that in multinucleate PMCs the cortical ring leads to the consolidation of chromosomes into common spindle and to meiotic restitution.
Asunto(s)
Núcleo Celular/fisiología , Citoesqueleto/ultraestructura , Meiosis/fisiología , Polen/citología , Profase/fisiología , Zea mays/citología , Núcleo Celular/ultraestructura , Técnicas Citológicas , Haploidia , Polen/ultraestructura , Zea mays/genética , Zea mays/ultraestructuraRESUMEN
Arrest of chromosomes at bouquet configuration at zygothene leads to meiotic restitution in some haploids and allohaploids in cereals: univalents are transported preferentially to one spindle pole in bipolar spindle because of their oriented position in the beginning of prometaphase.
Asunto(s)
Cromosomas de las Plantas/fisiología , Meiosis , Poaceae/fisiología , Quimera , Huso Acromático/fisiologíaRESUMEN
Abnormalities of plant meiotic division leading to abnormal meiotic products are summarized schematically in the paper. Causes of formation of monads, abnormal diads, triads, pentads, polyads, etc. have been observed in meiosis with both successive and simultaneous cytokinesis.
Asunto(s)
Meiosis , Células VegetalesRESUMEN
An overview of a set of our previous papers titled "Dynamics of microtubular cytoskeleton in higher plant meiosis" is presented, in addition to some data on subcellular mechanisms underlying cytoskeleton reorganization during meiotic division in pollen mother cells. An illustrated scheme of cytoskeleton rearrangements during plant meiosis, both with successive and simultaneous cytokinesis, is given.
Asunto(s)
Citoesqueleto/ultraestructura , Meiosis , Fenómenos Fisiológicos de las Plantas , Quimera , Citoesqueleto/fisiología , Microtúbulos/ultraestructura , Huso Acromático/ultraestructuraRESUMEN
Rearrangements of microtubular cytoskeleton during telophase in pollen mother cells of some dicotyledon plants with the simultaneous cytokinesis during normal and abnormal meiosis were studied. At telophase I, a potentially functional phragmoplast forms between daughter nuclei, but no cell plate is present. During interkinesis, the phragmoplast plays the role of an interphase cytoskeleton array. Dynamics of microtubule reorganization in polar regions of the telophase spindle is discussed in addition to the role played by microtubule convergence centers in cytoskeleton rearrangements during meiosis.
Asunto(s)
Citocinesis , Citoesqueleto/metabolismo , Meiosis , Fenómenos Fisiológicos de las Plantas , Citoesqueleto/ultraestructura , Microtúbulos , Polen/fisiología , TelofaseRESUMEN
The abnormal cytoskeleton cycle in meiosis in pollen mother cells of cereal wide hybrids F reveals the role of polar microtubules in phragmoplast formation during successive cytokinesis. The cytoskeletal rearrangements during successive and simultaneous cytokinesis in higher plant meiosis are compared.
Asunto(s)
Agropyron/citología , Citocinesis , Meiosis , Microtúbulos/ultraestructura , Triticum/citología , Agropyron/ultraestructura , Triticum/ultraestructuraRESUMEN
In this study we analysed the terminal step of cytoskeleton cycle in higher plant meiosis: transition from phragmoplast to radial interphase configuration. Wild type meiosis in a range of mono- and dicotyledonous species was studied. A number of cytoskeleton abnormalities on this stage was described in meiotic mutants, haploids and wide hybrids of various species. We described processes of cytoskeleton rearrangements on this stage: disjunction of phragmoplast MTs, their shortening and the role of daughter cell membranes. The independence of the interphase radial MT system formation from the previous steps of cytoskeleton cycle and from nuclear envelope cycle is proposed.
Asunto(s)
Citoesqueleto/ultraestructura , Meiosis , Fenómenos Fisiológicos de las Plantas , Quimera , Microtúbulos/ultraestructura , Huso Acromático/ultraestructuraRESUMEN
The inability of phragmoplast to stop its centrifugal movement after reaching the mother cell membrane is described in abnormal meiosis with the arrest of cell plate formation. The excess of phragmoplast expansion leads to rotation of the whole telophase figure (phragmoplast with daughter nuclei) within the cell through 90 degrees. It has been suggested that this phenomenon may occur because of a the lack of signal stopping cytokinesis. Such a signal arises due to formation of daughter cell membranes.
Asunto(s)
División Celular , Células Vegetales , Fenómenos Fisiológicos de las Plantas , Agropyron/citología , Transporte Biológico , Citocinesis/fisiología , Citoesqueleto/metabolismo , Meiosis , Secale/citología , Triticum/citología , Zea mays/citologíaRESUMEN
Intracellular morphological processes of successive cytokinesis in cereal pollen mother cells during normal and abnormal meiosis were studied. It was shown that the central spindle fiber system transforms into a phragmoplast at telophase. A model of centrifugal movement of the phragmoplast as a modification of B-anaphase has been proposed.
Asunto(s)
Citoesqueleto/metabolismo , Meiosis , Anafase , Citocinesis , Citoesqueleto/ultraestructura , Grano Comestible/fisiología , Polen/fisiología , Huso Acromático/metabolismo , Huso Acromático/ultraestructuraRESUMEN
Morphogenesis and functioning of polyarchal spindles in higher plant meiosis were studied. A mechanism of anastral spindle formation in discussed.
Asunto(s)
Meiosis , Huso Acromático/ultraestructura , Morfogénesis , Desarrollo de la Planta , Fenómenos Fisiológicos de las Plantas , Polen/citología , Polen/fisiologíaRESUMEN
Cytoskeleton abnormalities leading to the formation of restitution nuclei, and to the reunion of segregated daughter chromosome groups in the higher plant meiosis are reviewed.
Asunto(s)
Cromosomas de las Plantas , Citoesqueleto/genética , Meiosis/genética , Células Vegetales , Plantas/genéticaRESUMEN
A list of 24 abnormal plant spindles observed in meiotic division of PMCs in wide hybrids, meiotic mutants, haploids, polyploids has been presented. The abonormalities arranged according to the course of normal prometaphase are provided with descriptions of their morphogenesis and consequences, microphotographs and schemes. The spindle abnormalities leading to meiotic restitution are registered.
Asunto(s)
Células Vegetales , Huso Acromático/patología , División Celular , Meiosis/fisiología , Huso Acromático/ultraestructuraRESUMEN
This review involves consideration of morphological and functional aspects of cytokinesis, such as role of microtubule and actin cytoskeleton as well as mechanisms of cell plate formation and phragmoplast expansion, spatial control of division plan and cell cycle regulation, in addition to newly discovered mutations. Recent progress in understanding mechanisms of cytokinesis in the plant cell is discussed.
Asunto(s)
División Celular/fisiología , Células Vegetales , Actinas/fisiología , Citocinesis/genética , Citocinesis/fisiología , Citoesqueleto/metabolismo , Microtúbulos/metabolismo , MutaciónRESUMEN
By means of morphological analyses of meiotic abnormalities in pollen mother cells of cereal distant hybrids, processes of cytoskeleton cycle at the middle prometaphase (chaotic stage) were studied. It was shown that elements of the bipolar spindle (central and opposite kinetochore fibres) are formed at the chaotic stage of meiotic prometaphase.
Asunto(s)
Meiosis , Microtúbulos/ultraestructura , Triticum/fisiología , Polen/fisiología , PrometafaseRESUMEN
By means of morphological analyses of meiotic abnormalities in pollen mother cells (PMCs) of cereal wide hybrids, haploids and meiotic mutants, the processes involved in cytoskeleton cycle at late prometaphase (a sub-stage of transition from chaotic figure to bipolar spindle) were studied. A significance of the four processes of late prometaphase--axial orientation, lateral association, consolidation and convergance of spindle fibers--is discussed.