A trigeneric hybrid between Hordeum, Aegilops, and Secale

Genome ◽  
1992 ◽  
Vol 35 (4) ◽  
pp. 647-649 ◽  
Author(s):  
A. Cabrera ◽  
A. Martin
Keyword(s):  
Chromosome Number ◽  
Chromosome Pairing ◽  
Seed Set ◽  
Female Parent ◽  
Hybrid Plant ◽  
Male Parent ◽  
Cytological Analysis ◽  
Pollen Mother Cells ◽  
Mother Cells

A trigeneric hybrid between Hordeum, Aegilops, and Secale was synthesized. The female parent was a fertile amphiploid between H. chilense and A. squarrosa and the male parent was S. cereale. The hybrid plant had the expected chromosome number of 2n = 21. Cytological analysis of pollen mother cells revealed no chromosome pairing. Morphology of the HchDR hybrid plant was similar to that of the Aegilops. The hybrid was sterile and no seed set was observed even after colchicine treeatment.Key words: Hordeum, Aegilops, Secale, trigeneric hybrid, cytology.

A natural first-generation hybrid between Rorippa barbareaefolia and R. islandica

1968 ◽  
Vol 46 (8) ◽  
pp. 1079-1081
Author(s):  
Gerald A. Mulligan ◽  
A. E. Porsild
Keyword(s):  
First Generation ◽  
Female Parent ◽  
Yukon Territory ◽  
Male Parent ◽  
Male Sterile ◽  
Pollen Mother Cells ◽  
Mother Cells ◽  
Generation Hybrid

All the seeds taken from a fruiting specimen of Rorippa barbareaefolia (2n = 16) growing in the Yukon Territory produced plants with 24 somatic chromosomes. These plants were first-generation hybrids between R. barbareaefolia (2n = 16) and R. islandica (2n = 23). The female parent, R. barbareaefolia, was male sterile. Pairing configurations in pollen mother cells of these first generation hybrids suggested that the male parent, R. islandica, was autotetraploid.

scholarly journals Cytological Analysis of a Clethra alnifolia `Hokie Pink' × C. pringlei Hybrid

HortScience ◽  
2005 ◽  
Vol 40 (2) ◽  
pp. 339-342
Author(s):  
Sandra M. Reed
Keyword(s):  
Chromosome Number ◽  
Cold Hardiness ◽  
Male Gamete ◽  
Cytological Analysis ◽  
Root Tips ◽  
Chromosome Counts ◽  
Pollen Mother Cells ◽  
Size And Shape ◽  
Mother Cells ◽  
Deciduous Shrub

Clethra alnifolia L., a native deciduous shrub cultivated as an ornamental, was recently hybridized with C. pringlei S. Wats. The purpose of this hybridization was to combine the cold hardiness and adaptability of C. alnifolia with the ornamental foliage of C. pringlei. While most of the C. alnifolia × C. pringlei hybrids more closely resembled C. alnifolia than the paternal species, a `Hokie Pink' × C. pringlei hybrid (NA71586) with foliage that flushes red like C. pringlei was recovered. The objectives of this study were to analyze cytologically the F1 and produce a F2 population from NA71586. Chromosome counts from root tips cells indicated that NA71586 has 32 chromosomes. Since the chromosome number of C. alnifolia is 2n = 32 and that of C. pringlei was found to be 2n = 16, NA71586 appears to have developed following fertilization of a C. alnifolia egg with an unreduced male gamete from C. pringlei. Both `Hokie Pink' and C. pringlei exhibited primarily bivalent pairing in pollen mother cells (PMCs). Over half of the PMCs from NA71586 contained 16 bivalents, indicating substantial homology within the C. alnifolia genome. It was theorized that C. alnifolia is either an autotetraploid that exhibits bivalent pairing or a segmental allotetraploid produced from hybridization of species with similar genomes. More than 700 F2 progeny were obtained from self-pollination of NA71586. Although many of the F2 progeny resembled NA71586, variation in foliage color, size and shape was apparent in the population.

Morphology and cytology of induced hexaploid of Elymus canadensis and its backcross derivatives—pentaploids, tetrasomics, and trisomics

Genome ◽  
1990 ◽  
Vol 33 (3) ◽  
pp. 389-394 ◽  
Author(s):  
C. H. Park ◽  
P. D. Walton
Keyword(s):  
Tissue Culture ◽  
Chromosome Pairing ◽  
Seed Set ◽  
Chiasma Formation ◽  
Tetraploid Species ◽  
Genomic Constitution ◽  
Stainable Pollen ◽  
Pollen Mother Cells ◽  
Elymus Canadensis ◽  
Mother Cells

A tissue culture induced octoploid of Elymus canadensis was crossed with two accessions ("Canada" and "Montana") of the same tetraploid species to produce hexaploids. Hexaploid (2n = 42) and near-hexaploid progeny (2n = 43 or 40) obtained from the crosses were morphologically vigorous but either partially or completely sterile. Mean frequencies of univalents and trivalents in the hexaploid pollen mother cells at metaphase I were 3 or 4 and 2 to 4 per cell, respectively. In view of the genomic constitution of the parents, the hexaploids were expected to be genomically double triploids. Nevertheless, bivalents, averaging 14–17 per cell, predominated. This might be due to the failure of chiasma formation and chiasma terminalization. One hexaploid plant was backcrossed to the tetraploid. The progeny consisted of one pentaploid and five aneuploids including one tetrasomic and two trisomics. All of the progeny from the backcrosses were less vigorous than aneuploids at the near-hexaploid level. Tetrasomics and trisomics had stainable pollen and a 17–19% seed set. Two trisomic plants were morphologically indistinguishable from each other and predominantly showed chromosome pairing of 14 II + 1 I. This indicates failure of chiasma formation and chiasma terminalization between homologous chromosomes.Key words: Elymus canadensis, hexaploids, tetrasomics, trisomics, meiosis.

scholarly journals Meiotic Chromosome Behavior and Capsule Setting in Doritaenopsis Hybrids

2008 ◽  
Vol 133 (1) ◽  
pp. 107-116 ◽  
Author(s):  
Pablo Bolaños-Villegas ◽  
Shih-Wen Chin ◽  
Fure-Chyi Chen
Keyword(s):  
Cell Division ◽  
Pollen Mother Cell ◽  
Chromosome Pairing ◽  
Chromosomal Aberrations ◽  
High Frequency ◽  
Mother Cell ◽  
Seed Set ◽  
Pollen Viability ◽  
High Pollen ◽  
Mother Cells

The development of new cultivars in Doritaenopsis Guillaum. & Lami orchids is often hindered by factors such as low seed count in hybrids. Cytological study may offer the ability to develop new hybrids by revealing cultivars with good chromosome pairing and high pollen viability, which are somewhat difficult to obtain under current breeding programs. Cross pollination, pollen viability, and chromosomal behavior during meiosis were analyzed to reveal the relation between seed fertility and capsule set in Doritaenopsis hybrids. The number of mature capsules harvested and their relative seed content were used as indices of crossing availability. The results of meiosis were evaluated according to pollen viability detected by fluorescein diacetate and quantification of sporad types by acid fuchsin staining. Chromosome number and pairing at meiosis were observed in root tips or in samples of pollen mother cells. A positive relation was found among high seed set, high frequency of viable tetrads, high degree of chromosome pairing, and low frequency of chromosomal aberrations such as inversions and translocations. On the basis of these factors, three types of hybrids could be distinguished. In type one hybrids, chromosomes paired as bivalents, pollen mother cells divided into tetrads, and capsule setting occurred after pollination of pollen acceptors. In type two hybrids, chromosomes remained mainly as univalents that developed into micromeiocytes, pollen mother cell division was disrupted, and seed recovery was low after pollination. Type three hybrids showed chromosomes paired mostly as multivalents, chromosome bridges, pollen mother cell division with massive failure, and little fertility. In Doritaenopsis orchids, high pollen viability and high fertility depends on a high frequency of normal tetrads, and low seed set in cross-pollination is predicted with micronuclei in the end products of meiosis. The occurrence of chromosomal aberrations may suggest a process of genome differentiation that could compromise breeding efforts if not taken into consideration.

scholarly journals Meiosis in Oenothera missouriensis

1933 ◽  
Vol 113 (780) ◽  
pp. 57-70 ◽  
Keyword(s):  
Chromosome Pairing ◽  
Cytological Study ◽  
Stage Ii ◽  
Species Hybrid ◽  
Final Solution ◽  
Pollen Mother Cells ◽  
Closed Circle ◽  
Somatic Number ◽  
Mother Cells ◽  
Species Hybrids

A cytological study of the meiotic phenomena in Oenothera may not need an excuse in spite of the exhaustive studies of the genus made by numerous competent cytologists of this century. Up to the present time, all the investigators of Oenothera cytology have been successful in establishing that the basic ( n ) number of chromosomes in this genus is 7; although tetraploid (Gates, 1911), triploid (Cathcheside, 1931), and trisomic numbers might occur either naturally (by mutation) or could be produced by experiment. It is also known that the somatic number of chromosomes corresponds with the number of chromosome bodies in the diakinesis and metaphase of the heterotypic division.. Thus in diploid Oenothera species, hybrid, or mutant at the diakinesis of pollen mother cells 14 chromosomes have been shown to exist, withouth any doubt, in the configuration of a closed circle, in 7 ring pairs, or a mixtrue of free pairs and closed circles. Mathematically, there are 15 possible configurations in which 14 chromosomes can arrange themselves in the form of closed circle, ring pairs, or a combination of ring pairs and closed circles (Cleland and Blakeslee, 1931; Darlington, 1931). Of these 15 Possible configurations 13 have already been reported in various Oenothera species, hybrids and mutants (Darlington, 1931). Regarding the origin and significance of these chromosome configurations invsestigators have not yet reached an agreed opinion. Apart from the genetical significance, the much disputed cytological question of parasynaptic and telosynaptic methods of chromosome pairing is yet far from a final solution. In oenothera both the methods of pairing have strong sup-porters in consideration of observed cytological facts. The fact are (i) the continuous spireme (in leptotene stage); (ii) the pachynema and the diakinesis consisting of the 14 chromosomes arranged end to end. This arragement, known as catenation of chromosomes, favours the telosynaptic rather than the parasynaptic union. Wheras (i) double threads at the prophase, (ii) the looping of the threads, and (iii) the half number of bodies (7 ring pairs) at the diakinesis support the parasynaptic method of pairing of chromosomes. The occurence of a complete catenation of 14 chromosomes in some Oenotheras and the presence of 7 free pairs in others naturally suggests the question-whether they can be correlated with the two methods of chromosome-pairing in the meiosis of Oenothera .

The Effect of Spindle Inhibitors Applied before Meiosis on Meiotic Chromosome Pairing

1973 ◽  
Vol 12 (1) ◽  
pp. 143-161 ◽  
Author(s):  
G. A. DOVER ◽  
R. RILEY
Keyword(s):  
Chromosome Pairing ◽  
Chloral Hydrate ◽  
Control Mechanism ◽  
Meiotic Chromosome ◽  
Chiasma Formation ◽  
Meiotic Pairing ◽  
Mitotic Spindles ◽  
Pollen Mother Cells ◽  
Meiotic Chromosome Pairing ◽  
Mother Cells

Injection of 0.5% colchicine into immature tillers of genotypes of Triticum aestivum, T. aestivum x Aegilops mutica and T. aestivum x Secale cereale hybrids induces asynapsis at first meiotic metaphase irrespective of the homologous or homoeologous nature of the potential pairing chromosomes. The induction of asynapsis occurs at a time during and immediately following the last premeiotic mitosis of pollen mother cells. No disruption of synapsis and chiasma formation occurs in anthers having pollen mother cells originally at leptotene or immediately prior to leptotene when cultured in White's medium plus colchicine. Tetraploid and octaploid pollen mother cells resulting from the disruption of premeiotic spindles by colchicine show pairing of chromosomes only in bivalents, in genotypes normally having a degree of multivalent pairing configurations. The induction of multipolar mitotic spindles with 0.01% colchicine results in the development of pollen mother cell mosaics with different numbers of chromosomes. Such cells show high levels of chromosome pairing, including multivalents, in some genotypes that normally have very little chromosome pairing. The injection of 0.5% chloral hydrate during the last premeiotic mitosis of the archesporium causes no disturbances of meiotic pairing. The results are discussed with reference to the hypothesis that the control mechanism of meiotic chromosome pairing involves centromeric microtubules of the spindle (not affected by chloral hydrate) that are responsible for the positional adjustment, during the last mitotic anaphase, of potential pairing partners.

Genomic constitution of the allo-octoploid Elymus tenuis (Poaceae: Triticeae) of New Zealand

2010 ◽  
Vol 23 (5) ◽  
pp. 381 ◽  
Author(s):  
Hai-Qin Zhang ◽  
Xue Bai ◽  
Bao-Rong Lu ◽  
Henry E. Connor ◽  
Yong-Hong Zhou
Keyword(s):  
New Zealand ◽  
Chromosome Pairing ◽  
Interspecific Hybrids ◽  
Genomic Constitution ◽  
Pollen Mother Cells ◽  
Mother Cells

Elymus tenuis (Buch.) Á.Löve et Connor is a perennial octoploid (2n = 56) wheatgrass endemic to New Zealand. To investigate its genomic constitution, four artificial interspecific hybrids between E. tenuis and E. enysii (2n = 4x = 28, HW), and E. solandri (2n = 6x = 42, StYW) and E. multiflorus (2n = 6x = 42, StYW) were studied cytologically. Meioses in pollen mother cells (PMCs) of the hybrids showed relatively high chromosome pairing, with an average of 13.50 in E. enysii × E. tenuis, 20.22 in E. solandri × E. tenuis, 19.62 in E. multiflorus × E. tenuis, and 20.00 in E. tenuis × E. multiflorus bivalents per cell, respectively. The results indicate that E. tenuis is an allo-octoploid species, with the new and unique genomic constitution StYHW. An autochthonous origin is proposed for it.

Ultrastructure of meiotic pairing in B chromosomes of Crepis capillaris. I. One-B and two-B pollen mother cells

Genome ◽  
1989 ◽  
Vol 32 (4) ◽  
pp. 611-621 ◽  
Author(s):  
G. H. Jones ◽  
J. A. F. Whitehorn ◽  
S. M. Albini
Keyword(s):  
Synaptonemal Complex ◽  
Chromosome Pairing ◽  
Complex Surface ◽  
B Chromosome ◽  
B Chromosomes ◽  
Meiotic Pairing ◽  
Pollen Mother Cells ◽  
Crepis Capillaris ◽  
Axis Length ◽  
Mother Cells

Chromosome pairing of a small metacentric B chromosome in Crepis capillaris has been studied by synaptonemal complex surface spreading of pollen mother cells containing either one or two B chromosomes. The B-chromosome axis, on average, represents about 8.7% of the axis length of the standard A-chromosome set, which is less than the corresponding values for DNA content (10.6%) and mitotic chromosome volume (13.6%). Single B chromosomes commonly undergo fold-back pairing to give a symmetrical hairpin loop, which supports earlier suggestions that this B chromosome is an isochromosome. Two B chromosomes may show interarm pairing, exclusively, or interchromosome pairing, exclusively, or combinations of the two. Near the centromeres pairing occurs preferentially between arms of the same chromosome, but chromosome ends show random association. Some B chromosomes show anomalous pairing configurations, which may reflect further orders of reverse repeats within arms or, alternatively, nonhomologous pairing. The period of B-chromosome pairing is confined almost exclusively to zygotene, when the standard A chromosomes are pairing, but within this period their pairing is delayed relative to the A set. Individual B chromosomes at zygotene contain from one to three separate synaptonemal complex segments. These are widely distributed within the chromosomes, mainly in distal and interstitial regions; pairing is delayed around the centromere.Key words: B chromosomes, isochromosomes, synaptonemal complex.

Chromosome pairing in triploid and tetraploid hybrids in Elytrigia (Triticeae; Poaceae)

1984 ◽  
Vol 26 (5) ◽  
pp. 519-522 ◽  
Author(s):  
Patrick E. McGuire
Keyword(s):  
Chromosome Pairing ◽  
Genome Analysis ◽  
Triploid Hybrid ◽  
Pollen Mother Cells ◽  
Tetraploid Hybrid ◽  
A Genome ◽  
Mother Cells ◽  
Metaphase I

Mean chromosome pairing of 5.14I + 1.28II (rod) + 3.86II (ring) + 1.47III + 0.11IV (open) + 0.11V was observed in pollen mother cells at metaphase I in the triploid hybrid Elytrigia scirpea (K. Presl) Holub, 2n = 4x = 28 × E. bessarabica (Savul. et Rayss) Dubrovik, 2n = 4x = 14. Mean chromosome pairing of 3.71I + 2.29II (rod) + 1.82II (ring) + 2.64III + 0.29IV (open) was observed in the triploid hybrid E. curvifolia (Lange) Holub, 2n = 4x = 28 × E. bessarabica. Mean chromosome pairing of 3.00I + 0.93II (rod) + 1.57II (ring) + 1.36III + 1.79IV (open) + 1.I4IV (closed) + 0.79V was observed in the tetraploid hybrid E. junceiformis Löve et Löve, 2n = 4x = 28 × E. curvifolia. The first hybrid provides the first evidence by genome analysis that E. bessarabica possesses a genome (designated Eb) which is closely related to the genomes of E. scirpea (ES and ESC) and hence to the E genome of E. elongata (Host) Nevski, 2n = 2x = 14. The second and third hybrids provide the first evidence that the two genomes of E. curvifolia (designated EC and ECU) are related to the Eb genome of E. bessarabica and thus to the E genome of E. elongata.Key words: Elytrigia, homoeology, Triticum, phylogeny, triploid, tetraploid.

Induction of parthenogenesis, and chromosome behavior in plants of parthenogenetic origin in cotton (Gossypium hirsutum)

Genome ◽  
1991 ◽  
Vol 34 (2) ◽  
pp. 255-260 ◽  
Author(s):  
Zhou Shi-Qi ◽  
Qian De-Qi ◽  
Cao Xiu-Yun
Keyword(s):  
Gossypium Hirsutum ◽  
Biological Treatment ◽  
Seed Set ◽  
Hibiscus Cannabinus ◽  
Root Tips ◽  
Chromosome Behavior ◽  
Flower Buds ◽  
Physical Treatment ◽  
Pollen Mother Cells ◽  
Mother Cells

Different chemical, physical, and biological treatments were applied to emasculated flower buds of cotton hybrids (Gossypium hirsutum, 2n = 4x = 52) of various genotypes with the purpose of inducing haploid parthenogenesis. Of the treatments applied, the most effective chemical treatment was 0.2% colchicine in 0.2% dimethyl sulfoxide (1.22% parthenogenetic seed set), the most effective physical treatment was high temperature (2.66% parthenogenetic seed set), and the most effective biological treatment was pollination with Hibiscus cannabinus pollen (2.33% parthenogenetic seed set). In the progeny of five plants of parthenogenetic origin, chromosome number and meiotic behavior were studied. All were mixoploids at the dihaploid level and yet set bolls almost like normal allotetraploids. Chromosome numbers ranged from 12 to 56 in the root tips within plants, with a somewhat less pronounced variation between pollen mother cells. At meiotic metaphase I in pollen mother cells 89.8% of the chromosomes were associated. Of the bivalents 23.3% showed AA pairing, 18.7% showed DD pairing, and 18.4% showed AD pairing. Trivalents and higher multivalents involved 29.4% of the chromosomes, and 10.2% were univalents. Anaphase I segregation was often unequal. Yet fertility was as high as in the allotetraploid. It is possible that the second generation was formed by parthenogenesis after restitution in the embryonic mother cells.Key words: Gossypium hirsutum, cotton, parthenogenesis, mixoploidy, meiosis fertility.

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