Environmental induction of high frequency 2n pollen formation in diploid Solanum

1983 ◽  
Vol 25 (6) ◽  
pp. 609-615 ◽  
Author(s):  
N. A. McHale
Keyword(s):  
High Frequency ◽  
The Other ◽  
Similar Response ◽  
2N Pollen ◽  
Flowering Period ◽  
Field Site ◽  
Phenotypic Stability ◽  
Mean Frequency ◽  
Environmental Induction ◽  
Pollen Formation

Ten genotypes of Solanum phureja Juz. and Buk. producing 2n pollen via fused (FS) and tripolar (TPS) spindles at the second meiotic division were grown in 2 consecutive years at a cool field site (E1, 8–22 °C) and in a warm greenhouse (E2, 14–40 °C) to examine environmental effects on mean frequency and phenotypic stability of 2n pollen production. Overall frequencies of big pollen (BP) and dyad formation were substantially higher in E1 in both years. The stable standard (154-1) gave almost complete expressions of dyads in E1, with no bud below 99%. Four other genotypes (413, 414, 416, 417) gave a similar response in E1, producing mean dyad frequencies between 93 and 99%, with no bud below 80%. The other four genotypes (420, 424, 427, 429) and the variable standard (127–14) produced higher dyad frequencies in E1 versus E2, but their phenotypes remained variable in E1, showing disparities up to 79% between buds of a single collection. The fidelity of stable and variable phenotypes in E1 was examined by scoring dyad frequencies in putatively stable (413, 414, 415, 416) versus variable (420, 424, 427, 127–14) genotypes at four dates spanning the flowering period in this environment. The four stable genotypes showed consistent expression of high dyad frequency (86–99%) at all four dates. In contrast, dyad frequencies of the variable genotypes were substantially lower and more variable between and within collections.

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 High frequency 2n pollen formation in black poplar (Populus nigra L.) induced by colchicine

2019 ◽  
Vol 47 (3) ◽  
Author(s):  
Wenting XU ◽  
Yan ZHANG ◽  
Liqin GUO ◽  
Jian ZHAO ◽  
Zunzheng WEI ◽  
...  
Keyword(s):  
High Frequency ◽  
Colchicine Treatment ◽  
Tree Breeding ◽  
Populus Nigra ◽  
Digital Object Identifier ◽  
2N Pollen ◽  
Digital Object ◽  
The World ◽  
Pollen Formation ◽  
First Time

Populus nigra L. is one of the most important male genetic donors in populus genetic improvement and tree breeding over the world. Many excellent Populus nigra clones are identified as triploids potentially obtaining by hybridization of 2n pollen and normal oogamete. This study revealed the cytological mechanism of 2n pollen formation in Populus nigra L. for the first time and concluded the best treated combination of colchicine treatment, which obtained 2n pollen with the highest rate reaching at 87.11% (even 100% 2n pollen in some floral buds) which made the polyploid hybridization utilizing 2n pollen in section Aigeiros possible.   ********* In press - Online First. Article has been peer reviewed, accepted for publication and published online without pagination. It will receive pagination when the issue will be ready for publishing as a complete number (Volume 47, Issue 3, 2019). The article is searchable and citable by Digital Object Identifier (DOI). DOI link will become active after the article will be included in the complete issue. *********

THE INHERITANCE OF 2n POLLEN FORMATION IN DIPLOID ALFALFA MEDICAGO SATIVA

1982 ◽  
Vol 24 (3) ◽  
pp. 315-323 ◽  
Author(s):  
T. J. McCoy
Keyword(s):  
Medicago Sativa ◽  
High Frequency ◽  
Seed Set ◽  
Single Gene ◽  
Recessive Gene ◽  
2N Pollen ◽  
Good Seed ◽  
Ploidy Levels ◽  
Pollen Formation ◽  
Diploid Level

The inheritance of 2n pollen formation was studied in two diploid clones of alfalfa, Medicago sativa L. The two clones consistently produced a high frequency of 2n pollen, and they also porduced good seed set when used as males in 4x-2x crosses due to the functioning of 2n(2x) pollen. For the inheritance study the two clones were crossed with diploid clones of cultivated alfalfa at the diploid level (CADL), and with several clones of diploid M. falcata. In segregating families, plants that produced a high frequency of 2n pollen were identified by good seed set when used as males in 4x-2x crosses, and/or by bimodal pollen sizes. Plants that produced 4% or more 2n pollen generally produced greater than one seed per pollination in 4x-2x crosses, and these plants were considered 2n pollen producers. Analysis of self, F1, F2 and backcross (BC) families indicated 2n pollen formation was controlled by a single recessive gene, designated rp (restitution pollen). An allelism test indicated 2n pollen formation was controlled by the same recessive gene in both clones. Although there was considerable variation in the frequency of 2n pollen in rp/rp plants grown in different environments, all rp/rp plants consistently produced a significant frequency of 2n pollen (greater than 4%). Simple genetic control of 2n pollen formation has important implications in the evolution of the genus Medicago. In addition, 2n pollen formation controlled by a single gene may have potential application in the breeding of highly heterozygous tetraploids and in the efficient transfer of germplasm across ploidy levels.

scholarly journals Chance or Necessity—The Fungi Co−Occurring with Formica polyctena Ants

Insects ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 204
Author(s):  
Igor Siedlecki ◽  
Michał Gorczak ◽  
Alicja Okrasińska ◽  
Marta Wrzosek
Keyword(s):  
Molecular Identification ◽  
High Frequency ◽  
Its Rdna ◽  
The Other ◽  
Formica Polyctena ◽  
Ant Nests ◽  
Mutualistic Fungi ◽  
The Tropics ◽  
High Diversity ◽  
Better Than

Studies on carton nesting ants and domatia−dwelling ants have shown that ant–fungi interactions may be much more common and widespread than previously thought. Until now, studies focused predominantly on parasitic and mutualistic fungi–ant interactions occurring mostly in the tropics, neglecting less−obvious interactions involving the fungi common in ants’ surroundings in temperate climates. In our study, we characterized the mycobiota of the surroundings of Formica polyctena ants by identifying nearly 600 fungal colonies that were isolated externally from the bodies of F. polyctena workers. The ants were collected from mounds found in northern and central Poland. Isolated fungi were assigned to 20 genera via molecular identification (ITS rDNA barcoding). Among these, Penicillium strains were the most frequent, belonging to eight different taxonomic sections. Other common and widespread members of Eurotiales, such as Aspergillus spp., were isolated very rarely. In our study, we managed to characterize the genera of fungi commonly present on F. polyctena workers. Our results suggest that Penicillium, Trichoderma, Mucor, Schwanniomyces and Entomortierella are commonly present in F. polyctena surroundings. Additionally, the high diversity and high frequency of Penicillium colonies isolated from ants in this study suggest that representatives of this genus may be adapted to survive in ant nests environment better than the other fungal groups, or that they are preferentially sustained by the insects in nests.

Normal Synaptonemal Complex and Abnormal Recombination Nodules in Two Alleles of the Drosophila Meiotic Mutant mei-W68

Genetics ◽  
2003 ◽  
Vol 163 (4) ◽  
pp. 1337-1356 ◽  
Author(s):  
Adelaide T C Carpenter
Keyword(s):  
Electron Microscopy ◽  
Synaptonemal Complex ◽  
High Frequency ◽  
Serial Section ◽  
The Other ◽  
Wild Type ◽  
Recombination Nodules ◽  
Section Electron ◽  
Serial Section Electron Microscopy ◽  
Section Electron Microscopy

Abstract The meiotic phenotypes of two mutant alleles of the mei-W68 gene, 1 and L1, were studied by genetics and by serial-section electron microscopy. Despite no or reduced exchange, both mutant alleles have normal synaptonemal complex. However, neither has any early recombination nodules; instead, both exhibit high numbers of very long (up to 2 μm) structures here named “noodles.” These are hypothesized to be formed by the unchecked extension of identical but much shorter structures ephemerally seen in wild type, which may be precursors of early recombination nodules. Although the mei-W68L1 allele is identical to the mei-W681 allele in both the absence of early recombination nodules and a high frequency of noodles (i.e., it is amorphic for the noodle phene), it is hypomorphic in its effects on exchange and late recombination nodules. The differential effects of this allele on early and late recombination nodules are consistent with the hypothesis that Drosophila females have two separate recombination pathways—one for simple gene conversion, the other for exchange.

LONG DURATION ECHOES FROM AURORA, METEORS, AND IONOSPHERIC BACK-SCATTER

1953 ◽  
Vol 31 (2) ◽  
pp. 171-181 ◽  
Author(s):  
D. W. R. McKinley ◽  
Peter M. Millman
Keyword(s):  
Long Range ◽  
High Frequency ◽  
The Other ◽  
Very High Frequency ◽  
Long Duration ◽  
E Region ◽  
Very High ◽  
Visual Observations

In the course of the Ottawa meteor program some unusual echoes have been detected on 33 Mc. Echoes from the aurora are discussed and correlated with visual observations. Two mechanisms of radio reflections from the aurora have been proposed but the data here presented are insufficient to favor one over the other. On Aug. 4, 1948, six extremely long duration meteor echoes were observed which may have been due to abnormal ionospheric conditions. From time to time since August, 1948, a weak semipermanent echo has been recorded, usually appearing at a range of about 80 km., and enduring up to an hour. It is suggested that this echo is due to back-scatter from the same sources in the lower E-region that are presumed to be responsible for long-range very high frequency propagation.

scholarly journals Transduction mechanisms of bacteriophage ε15I. General properties of the system

1971 ◽  
Vol 18 (1) ◽  
pp. 9-19 ◽  
Author(s):  
R. W. Hedges
Keyword(s):  
High Frequency ◽  
Genetic Material ◽  
Recipient Strain ◽  
The Other ◽  
Donor Strain ◽  
General Properties ◽  
Show Evidence ◽  
Transduction Mechanisms ◽  
Defective Prophage

SUMMARYBacteriophageεγis capable of transduction both by replacement of a genetic segment of the recipient by the homologous genetic material from the donor strain and by the formation of defective transducing particles capable of lysogenizing the recipient strain ofS. anatum.The isolation of strains carrying such prophages, which have incorporated the lactose or arabinose operons, is reported. Lysogenic strains, carrying both normal and defective transducing prophage, form high-frequency transducing lysates. Other strains, carrying only defective prophage, show evidence that the association of prophage genes and transduced materials is stable since the loss of one frequently entails loss of the other.

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.

Relative clauses in Agul from a corpus-based perspective

2020 ◽  
Vol 73 (1) ◽  
pp. 113-158
Author(s):  
Timur Maisak
Keyword(s):  
High Frequency ◽  
Relative Clauses ◽  
High Ratio ◽  
The Other ◽  
The Core ◽  
Text Corpora ◽  
The Asymmetry ◽  
Intransitive Verbs ◽  
Syntactic Restrictions ◽  
Locative Case

AbstractThis paper gives an account of participial clauses in Agul (Lezgic, Nakh-Daghestanian), based on a sample of 858 headed noun-modifying clauses taken from two text corpora, one spoken and one written. Noun-modifying clauses in Agul do not show syntactic restrictions on what can be relativized, and hence they instantiate the type known as GNMCCs, or general noun-modifying clause constructions. As the text counts show, intransitive verbs are more frequent than transitives and experiencer verbs in participial clauses, and among intransitive verbs, locative statives with the roots ‘be’ and ‘stay, remain’ account for half of all the uses. The asymmetry between the different relativization targets is also significant. Among the core arguments, the intransitive subject (S) is the most frequent target, patient (P) occupies second place, and agent (A) is comparatively rare. The preference of S and, in general, of S and P over A also holds true for most other Nakh-Daghestanian languages for which comparable counts are available. At the same time, Agul stands apart from the other languages by its high ratio of non-core relativization which accounts for 42% of all participial clauses. Addressee, arguments and adjuncts encoded with a locative case, as well as more general place and time relativizations show especially high frequency, outnumbering such arguments as experiencers, recipients, and predicative and adnominal possessors. Possible reasons for the high ratio of non-argument relativization are discussed in the paper.

Sign in / Sign up

Export Citation Format

Share Document