scholarly journals Impact of cytomixis on the microspogenesis and formation of unreduced pollen grains in monocots

2017 ◽  
Vol 20 ◽  
pp. 26-30
Author(s):  
E. A. Kravets ◽  
S. H. Plohovskaya ◽  
I. I. Horyunova ◽  
A. I. Emets ◽  
Ya. B. Blume
Keyword(s):  
Meiotic Division ◽  
Functional Role ◽  
Fluorescent Microscopy ◽  
Pollen Grains ◽  
Allium Fistulosum ◽  
2N Pollen ◽  
Significant Progress ◽  
Unreduced Pollen ◽  
Meiotic Chromosomes ◽  
Allium Cepa L

Aim. Despite significant progress in the investigation of cytomixis its functional role and effect on the course of meiosis as well as mechanisms of 2n pollen grains formation is still not completely clear. We have studied the destination of cytomictic chromatin as well the mechanisms of unreduced microspores formation in species of monocots with spontaneous cytomixis. Methods. Light and fluorescent microscopy. Results. The cytomictic chromatin forms additional meiotic chromosomes in the recipient microsporocytes. Many of these meiotic chromosomes undergo rearrangement and fragmentation but retain their bivalent organization. Conclusions. Cytogenetic anomalies of microsporogenesis caused by activation of cytomixis in prophase may reflect meiosis stabilization mechanisms by assimilation and adaptation or diminution and reutilization of the introduced DNA. The main mechanism of polyploidization of microsporocytes and pollen grains in studied monocots is the restitution of the first meiotic division via the formation of a meta-anaphase 1 block.Keywords: cytomixis, microsporogenesis, additional (recipient) chromosomes, meta-anaphase 1 block, Lilium croceum Chaix., Allium cepa L., Allium fistulosum L.

CYTOLOGY OF 2n POLLEN FORMATION IN DIPLOID ALFALFA, MEDICAGO SATIVA

1979 ◽  
Vol 21 (4) ◽  
pp. 525-530 ◽  
Author(s):  
Nicholi Vorsa ◽  
E. T. Bingham
Keyword(s):  
Medicago Sativa ◽  
Seed Set ◽  
Pollen Grains ◽  
Genetic Constitution ◽  
2N Pollen ◽  
Diploid Parent ◽  
2N Gamete ◽  
Medicago Sativa L ◽  
Pollen Formation ◽  
Mother Cells

Four diploid (2x) clones of alfalfa, Medicago sativa L., which produced good seed set when used as male parents in 4x-2x crosses were selected for study. The 2x clones descended from 2x haploids of cultivated 4x alfalfa. Fertility in the 4x-2x cross was due to the production of pollen with the unreduced chromosome number (2n pollen) from the 2x parent. The cytological mechanism of 2n pollen formation was found to be disorientation of spindles at metaphase II in up to 38% of the pollen mother cells. Thus, both n and 2n pollen were produced by all four diploids examined. Normal spindles at metaphase II were oriented such that they defined the poles of a tetrahedron and resulted in normal tetrads in a tetrahedral arrangement. Disoriented spindles were basically parallel to each other and resulted in formation of dyads and occasionally a triad. Dyads developed into two 2n pollen grains; triads developed into one 2n and two n pollen grains. Since both n and 2n pollen grains are produced by the diploids, they can be maintained as diploids or they can be used as male parents in crosses to tetraploids. The genetic constitution of 2n pollen resulting from parallel spindles is similar to that expected after first division restitution of meiosis and much of the heterozygosity of the diploid parent is conserved in the gametes. The 2n gamete mechanism has potential application in germplasm transfer and in maximizing heterozygosity in tetraploid hybrids.

The relationship of reproductive biology to the rarity of endemic Aster curtus (Asteraceae)

1999 ◽  
Vol 77 (1) ◽  
pp. 140-149 ◽  
Author(s):  
David E Giblin ◽  
Clement W Hamilton
Keyword(s):  
Pacific Northwest ◽  
Reproductive Biology ◽  
Fluorescent Microscopy ◽  
Pollen Grains ◽  
Field Trials ◽  
Rare Plants ◽  
Glacial Outwash ◽  
Compatible Cross ◽  
Species Rarity ◽  
Filled Seeds

The fecundity of rare plants is a commonly used indicator of performance at the population or species level. However, accurately interpreting reproductive output requires an understanding of a particular species's breeding system. The purpose of this study was to determine if reproductive biology contributes to the restricted distribution of Aster curtus Cronq. We hypothesized that (i) A. curtus, like many Asteraceae species, is self-incompatible, and (ii) that pollinations between patches produce significantly more filled seeds than pollinations within patches. Fluorescent microscopy of pistils harvested after greenhouse pollination showed A. curtus to be partially self-compatible. Cross-pollination resulted in significantly more pollen grains per stigma and significantly greater pollen germination than self-pollination. Similarly, field pollination trials showed that between-patch crosses produced significantly more filled seeds than within-patch crosses. Nevertheless, within-patch pollinations produced substantial levels of filled seed. Results from the greenhouse and field trials suggest that the reproductive biology of A. curtus contributes little to its rarity. Understanding why A. curtus is rare has important implications to the conservation of the glacial outwash prairie. Moreover, the data from this research can be used in further developing predictive models for plant species rarity based on reproductive biology.Key words: Aster, endemic, Pacific Northwest, rarity, reproductive biology, self-incompatibility.

Allium cepa L. Allium fistulosum L. Allium ramosum L. Allium sativum L. Amaryllidaceae

2020 ◽  
pp. 159-169
Author(s):  
Narel Y. Paniagua-Zambrana ◽  
Rainer W. Bussmann ◽  
Carolina Romero
Keyword(s):  
Allium Cepa ◽  
Allium Sativum ◽  
Allium Fistulosum ◽  
Allium Cepa L

scholarly journals Morphological diversity of pollen from selected species of the genus Taraxacum, according to their ploidal level

2012 ◽  
Vol 61 (1) ◽  
pp. 65-69 ◽  
Author(s):  
Jolanta Marciniuk ◽  
Anna Rudzińska-Langwald
Keyword(s):  
Pollen Grains ◽  
Morphological Diversity ◽  
Great Variability ◽  
2N Pollen ◽  
Regular Type ◽  
Unknown Number ◽  
Species Being ◽  
The Way

The study of the morphology of pollen concerned eight species of the genus <i>Taraxacum</i>. Seven types were chosen with a different number of chromosomes belonging to the section <i>Palustria</i>: <i>Taraxacum paucilobum</i> 2n = 3x = 24, <i>T. subdolum</i> 2n = 3x =24, <i>T. subpolonicum</i> 2n =3x = 24, <i>T. vindobonense</i> 2n = 4x = 32, <i>T. trilobifolium</i> 2n = 4x = 32, <i>T. mendax</i> 2n = 5x = 40, <i>T. portentosum</i> 2n =? and one type from the section <i>Obliqua</i> - <i>T. platyglossum</i> 2n =?. Pollen from all the examined species was observed by SEM microscopy. A distinct relation exists between the morphology of pollen and the way of reproduction. Pollen of triploidal species, being compulsory apomicts, is characterized by a great variability of the size and a high percentage of deformed pollen grains. Tetraploids, being optional apomicts, produce regular pollen with a relatively even size. The regular type of pollen in pentaploidal <i>Taraxacum mendax</i> and in species with an unknown number of chromosomes (<i>Taraxacum portentosum</i> and <i>T. platyglossum</i>) suggests that these taxa are optional apomicts.

A comparison of progeny from diallel crosses of diploid potato with regard to the frequencies of 2n-pollen grains

Euphytica ◽  
1995 ◽  
Vol 92 (3) ◽  
pp. 313-320
Author(s):  
Qu Dongyu ◽  
Zhu Dewei ◽  
M. S. Ramanna ◽  
E. Jacobsen
Keyword(s):  
Pollen Grains ◽  
Diploid Potato ◽  
2N Pollen ◽  
Diallel Crosses

scholarly journals A new and anomalous type of meiosis in a mantid, Callimantis antillarum saussure

1938 ◽  
Vol 125 (841) ◽  
pp. 516-523 ◽  
Keyword(s):  
Meiotic Division ◽  
Middle Part ◽  
Extreme Form ◽  
Diffuse Stage ◽  
Spindle Attachment ◽  
Meiotic Chromosomes ◽  
Male Sex

The general course of meiosis in the Orthoptera is remarkably constant from species to species, and even from one suborder to another. This is at any rate true of meiosis in the male sex; owing to technical difficulties, oogenesis has been studied in only a few species, but there seems no reason to believe that it is less uniform than spermatogenesis. Such deviations from normality as do occur seem to be of two main kinds. In some species the middle part of the prophase of the first meiotic division (pachytene, and sometimes diplotene as well) are replaced by a “diffuse stage” during which the chromosomes become almost impossible to fix and stain. Such a stage is apparently present in the peculiar orthopteran Schizodactylus monstrosus (McClung and Asana 1933, 1935)-In other species the chiasmata which usually occur more or less at random along the length of the meiotic chromosomes are localized in certain definite regions. Localization of chiasmata is seen in it's most extreme form in species of the genus Mecostethus (Acrididae), where only one chiasma is usually formed in each bivalent, just near the spindle attachment (White 1936).

Screening and incorporation of rust resistance from Allium cepa into bunching onion (Allium fistulosum) via alien chromosome addition

Genome ◽  
2015 ◽  
Vol 58 (4) ◽  
pp. 135-142 ◽  
Author(s):  
Tadayuki Wako ◽  
Ken-ichiro Yamashita ◽  
Hikaru Tsukazaki ◽  
Takayoshi Ohara ◽  
Akio Kojima ◽  
...  
Keyword(s):  
Allium Cepa ◽  
Rust Resistance ◽  
Rust Fungus ◽  
Allium Fistulosum ◽  
Addition Line ◽  
Chromosome Addition ◽  
Allium Cepa L ◽  
Alien Chromosome Addition ◽  
High Level ◽  
Bunching Onion

Bunching onion (Allium fistulosum L.; 2n = 16), bulb onion (Allium cepa L. Common onion group), and shallot (Allium cepa L. Aggregatum group) cultivars were inoculated with rust fungus, Puccinia allii, isolated from bunching onion. Bulb onions and shallots are highly resistant to rust, suggesting they would serve as useful resources for breeding rust resistant bunching onions. To identify the A. cepa chromosome(s) related to rust resistance, a complete set of eight A. fistulosum – shallot monosomic alien addition lines (MAALs) were inoculated with P. allii. At the seedling stage, FF+1A showed a high level of resistance in controlled-environment experiments, suggesting that the genes related to rust resistance could be located on shallot chromosome 1A. While MAAL, multi-chromosome addition line, and hypoallotriploid adult plants did not exhibit strong resistance to rust. In contrast to the high resistance of shallot, the addition line FF+1A+5A showed reproducibly high levels of rust resistance.

THREE MECHANISMS OF 2n POLLEN FORMATION IN DIPLOID POTATOES

1975 ◽  
Vol 17 (2) ◽  
pp. 217-225 ◽  
Author(s):  
D. W. S. Mok ◽  
S. J. Peloquin
Keyword(s):  
Meiotic Division ◽  
Genetic Data ◽  
The Other ◽  
Cleavage Furrow ◽  
2N Pollen ◽  
Parallel Spindles ◽  
Solatium Tuberosum ◽  
Pollen Formation ◽  
Group Tuberosum

Three mechanisms of 2n pollen formation observed in diploid hybrids between Solatium tuberosum Group Phureja (2x) and haploids of S. tuberosum Group Tuberosum (4x) are termed parallel spindles (ps), premature cytokinesis 1 (pc 1) and premature cytokinesis 2 (pc 2). A II spindles are parallel to each other in many cells of clones producing 2n pollen by ps. A single cleavage furrow follows and forms a dyad which generates two 2n microspores. The other two mechanisms, pc 1 and pc 2, produce 2n pollen by omission of the second meiotic division. Premature cytokinesis 1 (pc 1) involves asynchronized movement of bivalents to and from the M I plate and falling apart of chromatids at T I. A cleavage furrow follows the first meiotic division, no second division occurs and products of meiosis are dyads. Premature cytokinesis 2 (pc 2) exhibits no abnormalities at the first meiotic division. However, cytokinesis occurs prematurely at P II, no second division occurs, and only dyads are formed. Genetic data suggested that these three mechanisms may be controlled by single loci, and are inherited independently as simple recessives.

scholarly journals Colchicine did not affect the viability of induced 2n pollen in Populus tomentosa

Silva Fennica ◽  
2019 ◽  
Vol 53 (2) ◽  
Author(s):  
Yan Liu ◽  
Yuan Zhang ◽  
Qing Zhou ◽  
Jian Wu ◽  
Pingdong Zhang
Keyword(s):  
Pollen Germination ◽  
Pollen Viability ◽  
Pollen Grains ◽  
Populus Tomentosa ◽  
2N Pollen ◽  
Significant Difference ◽  
Diploid Pollen ◽  
Germination Experiments ◽  
Diploid Gametes

Colchicine is widely used as a mutagen to induce production of diploid gametes in plants. However, whether colchicine affects induced pollen viability remains unclear. To clarify whether colchicine affected the viability of induced pollen, we induced production of diploid pollen by colchicine, followed by pollen germination and crossing induced pollen with normal gametes to produce triploid in Carrière. The results showed that the predominant meiotic stages and the number of colchicine injections had significant effects on the occurrence rates of induced 2n pollen. When the colchicine injection was given at diakinesis, a significant decrease in the pollen production per bud was observed ( < 0.001). The morphology of the colchicine-induced 2n pollen was similar to that of the natural 2n pollen in its ectexine structure. The pollen germination experiments revealed that there was also no significant difference in germination rates between the induced diploid pollen and natural 2n pollen grains, and 68 triploids were created by crossing colchicine-induced pollen. Our findings revealed that colchicine injection could induce to produce 2n pollen and will not lead to dysfunction of induced diploid pollen.in vitroPopulus tomentosapP. tomentosa

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