Chromosome pairing in triploid hybrids and amphidiploids involving Lolium and diploid Festuca species

Genome ◽  
1990 ◽  
Vol 33 (4) ◽  
pp. 472-477 ◽  
Author(s):  
W. G. Morgan
Keyword(s):  
Chromosome Pairing ◽  
Phylogenetic Relationships ◽  
Meiotic Behaviour ◽  
Triploid Hybrid ◽  
Chromosome Size ◽  
Chromosome Homology ◽  
Precise Identification

Chromosome homology between Lolium and Festuca complements are assessed in triploid and tetraploid hybrids with variable doses of the different diploid genomes. In general, the chromosome pairing observed in the triploid hybrid gave a better prediction of the meiotic behaviour of the tetraploid amphidiploids than that found in the diploid hybrids. Differences in chromosome size between the complements allowed the precise identification of the chromosomes in chiasmate associations and there was evidence that most chromosome pairing was between homologues. In the triploid hybrids, associations between nonhomologous chromosomes were recorded. The results, based on chromosome pairing data, are briefly discussed in relation to genome homologies and phylogenetic relationships in the Lolium-Festuca complex.Key words: Lolium, Festuca, chromosome pairing, nonhomologous, triploid hybrids, amphidiploids.

CHROMOSOME RELATIONSHIPS BETWEEN THE CULTIVATED OAT AVENA SATIVA (6x) AND A. VENTRICOSA (2x)

1970 ◽  
Vol 12 (1) ◽  
pp. 36-43 ◽  
Author(s):  
Hugh Thomas
Keyword(s):  
Chromosome Pairing ◽  
Avena Sativa ◽  
Diploid Species ◽  
Meiotic Behaviour ◽  
Hexaploid Species ◽  
C Genome

Chromosome pairing in the F1 hybrid between the cultivated oat Avena sativa and a diploid species A. ventricosa, and in the derived amphiploid, shows that the diploid species is related to one of the genomes of the hexaploid species. The amount of chromosome pairing observed in complex interamphiploid hybrids demonstrates further that A. ventricosa is related to the C. genome of A. sativa. However, the chromosomes of the diploid species have become differentiated from that of the C genome of A. sativa and this is readily apparent in the meiotic behaviour of both the F1 hybrid and the amphiploid.

CHROMOSOME PAIRING IN TWO INTERSPECIFIC HYBRIDS OF TRIFOLIUM

1970 ◽  
Vol 12 (4) ◽  
pp. 790-794 ◽  
Author(s):  
Chi-Chang Chen ◽  
Pryce B. Gibson
Keyword(s):  
Phylogenetic Relationship ◽  
Chromosome Pairing ◽  
Trifolium Repens ◽  
Interspecific Hybrids ◽  
Triploid Hybrid ◽  
Close Phylogenetic Relationship ◽  
Metaphase I

Both Trifolium repens (2n = 32) and T. nigrescens (2n = 16) formed bivalents during meiosis. However, their triploid hybrid showed an average of 4.27 trivalents per microsporocyte at metaphase I. The frequency of trivalents in the hybrid between T. nigrescens and autotetraploid T. occidentale (2n = 32) was 5.69. The data are interpreted to indicate: (1) a possible autotetraploid origin of T. repens; and (2) a close phylogenetic relationship among T. repens, T. nigrescens and T. occidentale.

Meiotic behaviour of induced autotetraploids in Triticum L.

Genome ◽  
1990 ◽  
Vol 33 (2) ◽  
pp. 302-307 ◽  
Author(s):  
Yang Yen ◽  
Gordon Kimber
Keyword(s):  
Chromosome Pairing ◽  
Seed Set ◽  
Chromosome Association ◽  
Meiotic Behaviour ◽  
Meiotic Analysis

Colchicine-induced autotetraploids of Triticum speltoides, T. longissimum, T. sharonense, T. bicorne, T. uniaristatum, T. monococcum, and T. tauschii were all morphologically similar to but larger than their diploid forms. Seed set was lower than in the diploids except for the autotetraploid T. speltoides. Meiotic analysis showed fewer quadrivalents and more bivalents than would be expected in all of these autotetraploids. Arm-pair switch, indicated by complex trivalents and quadrivalents, was found and involved 0.1% of total chromosomes in T. umbellulatum, 0.5% in T. longissimum, 0.7% in both T. sharonense and T. tauschii, 6.3% in T. bicorne, and 15.3% in T. uniaristatum.Key words: meiosis, chromosome association, arm-pair switch, chromosome pairing, bivalentization.

Genome analysis of Thinopyrum junceiforme and T. sartorii

Genome ◽  
1992 ◽  
Vol 35 (5) ◽  
pp. 758-764 ◽  
Author(s):  
Zhi-Wu Liu ◽  
Richard R.-C. Wang
Keyword(s):  
Chromosome Pairing ◽  
Chromosome Banding ◽  
Triploid Hybrid ◽  
Meiotic Pairing ◽  
Organizational Changes ◽  
Banding Patterns ◽  
Small Satellites ◽  
Basic Genome ◽  
Dna Organization ◽  
Karyotype Analyses

Genome constitutions of Thinopyrum junceiforme (A. Löve and D. Löve) A. Löve (2n = 4x = 28) and T. sartorii (Boiss. &Heldr.) A. Löve (2n = 4x = 28) were determined by studying (i) meiotic pairing patterns in hybrids involving the two species and other pertinent hybrids; (ii) mitotic chromosome karyotypes based on length, arm ratio, and satellites; and (iii) C-banding patterns. New hybrids synthesized and reported are T. sartorii × T. bessarabicum (2n = 3x = 21), T. sartorii × (T. bessarabicum × T. elongatum) amphidiploid (2n = 4x = 28), and the reciprocal of the latter. Mean meiotic pairing in the triploid hybrid and the two tetraploid hybrids were 3.83 I + 3.92 II + 3.11 III, 0.931 + 7.46 II + 0.62 III + 2.44 IV + 0.07 V + 0.03 VI, and 3.41 I + 9.39 II + 0.74 III + 0.88 IV, respectively. Based on the chromosome pairing data, it can be concluded that T. junceiforme and T. sartorii have two versions (Jb and Je) of the J genome and behave like true allotetraploids owing to bivalentization. Karyotype analyses of the species and their hybrids with T. bessarabicum revealed minor structural differentiations of the genomes in the two species. Thinopyrum sartorii has one genome basically unchanged from the Jb genome of T. bessarabicum while another is a modified Je genome of T. elongatum. One genome of T. junceiforme is modified from Jb and the other is modified from Je. There are two pairs of large and one pair of small satellites in T. sartorii, but there are only one pair of each in T. junceiforme. Thinopyrum junceiforme is rich and T. sartorii is poor in interstitial C-bands for both sets of genomes. Thinopyrum sartorii has larger terminal C-bands on the Jb genome chromosomes than those of T. junceiforme. These organizational changes of chromosomes could not be detected by studying chromosome pairing alone. However, this study demonstrates that meiotic pairing is the first criterion for determining basic genome symbols. Other techniques, such as those involving chromosome banding, isozymes, and DNA probes, may then be used to detect differences in chromosome (or DNA) organization and gene expression.Key words: genome, hybrid, meiosis, karyotype, chromosome banding, speciation.

Genome analysis of Elymus alatavicus and E. batalinii (Poaceae: Triticeae)

1986 ◽  
Vol 28 (5) ◽  
pp. 770-776 ◽  
Author(s):  
Kevin B. Jensen ◽  
Douglas R. Dewey ◽  
Kay H. Asay
Keyword(s):  
Chromosome Pairing ◽  
Genome Analysis ◽  
Taxonomic Classification ◽  
Meiotic Behaviour ◽  
Pseudoroegneria Spicata ◽  
Mode Of Reproduction ◽  
The Relationship ◽  
Partial Fertility ◽  
Metaphase I

Elymus alatavicus (Drob.) A. Love and E. batalinii (Krasn.) A. Love were studied to determine (i) meiotic behaviour, (ii) the mode of reproduction, (iii) the relationship between the two species, (iv) genomic constitutions, and (v) the most logical taxonomic classification of both species. A series of F1 hybrids between E. alatavicus, E. batalinii, and six "analyzer" species were developed. Chromosome pairing was studied at metaphase I to identify genomic similarities or differences. The results showed that E. alatavicus and E. batalinii are caespitose, self-fertile allohexaploids (2n = 42) with the same genomic formula SSYYXX. The F1 hybrids between E. alatavicus and E. batalinii had complete pairing (21 bivalents) at metaphase I in 7% of the cells and almost complete pairing in the remaining cells. High chromosome pairing and partial fertility (4 seeds/plant) in the F1 hybrids shows that the two species are closely related. Hybrids were obtained between E. alatavicus or E. batalinii and the following "analyzer" species with known genomic formulas: Pseudoroegneria spicata (Pursh) A. Love, 2n = 14, SS; P. cognata (Hack.) A. Love, 2n = 14, SS; E. lanceolatus (Scribn. &Smith) Gould, 2n = 28, SSHH; E. trachycaulus1 (Link) Gould ex Shinners, 2n = 28, SSHH; E. mutabilis (Drob.) Tzvelev, 2n = 28, SSHH; and E. drobovii (Nevski) Tzvelev, 2n = 42, SSHHYY. Chromosome pairing in this series of hybrids demonstrated that E. alatavicus and E. batalinii contain an S and probably a Y genome plus an unknown genome, X, that may have been derived from Psathryostachys huashanica Keng or from Agropyron. Elymus alatavicus and E. batalinii are correctly classified in the genus Elymus.Key words: cytotaxonomy, Agropyron, meiosis, chromosome.

Cytogenetic studies of interspecific hybrids between diploid species of Festuca

1986 ◽  
Vol 28 (6) ◽  
pp. 921-925 ◽  
Author(s):  
W. G. Morgan ◽  
Hugh Thomas ◽  
M. Evans ◽  
M. Borrill
Keyword(s):  
Genome Size ◽  
Chromosome Pairing ◽  
Dna Content ◽  
Interspecific Hybrids ◽  
Parental Species ◽  
Diploid Species ◽  
Chromosome Size ◽  
Cytogenetic Studies ◽  
The Difference

Chromosome pairing in hybrids between diploid species of Festuca is described. The chromosome complements of the species from different taxonomic sections vary in chromosome size and DNA content. In interspecific hybrids involving species of the section Montanae there was a relationship between the difference in DNA content of the parental species and chromosome pairing in the F1 hybrids. The larger the difference between the DNA content of the parental species, the more pronounced the failure of chromosome pairing in the F1 hybrids. Factors other than divergence in genome size were also shown to have an effect on chromosome pairing in other hybrid combinations.Key words: chromosome pairing, DNA content, Festuca, hybrids (interspecific).

Interspecific hybrids between a transgenic rapeseed (Brassica napus) and related species: cytogenetical characterization and detection of the transgene

Genome ◽  
1993 ◽  
Vol 36 (6) ◽  
pp. 1099-1106 ◽  
Author(s):  
M. C. Kerlan ◽  
A. M. Chevre ◽  
F. Eber
Keyword(s):  
Chromosome Pairing ◽  
Related Species ◽  
Interspecific Hybrids ◽  
Plant Production ◽  
Triploid Hybrid ◽  
Bar Gene ◽  
Meiotic Behavior ◽  
Gene Dispersal ◽  
Gene Characterization ◽  
Transgenic Rapeseed

In interspecific hybrids produced between a transgenic rapeseed, an allotetraploid species, resistant to herbicide, phosphinotricin, and five diploid related species, the risk for gene introgression in weed genomes was explored through cytogenetic and bar gene characterizations. Among the 75 hybrids studied, most had the expected triploid structure, with the exception of B. napus – B. oleracea amphidiploid plants and one B. napus – S. arvensis amphidiploid plant. In triploid hybrid plants, the reciprocal hybrids did not exhibit any difference in their meiotic behavior. The comparison of the percentage of chromosome pairing in the hybrids with that of haploid rapeseed permit to conclude that allosyndesis between AC genomes and related species genomes took place. This possibility of recombination was confirmed by the presence of multivalent associations in all the interspecific hybrids. Nevertheless, in B. napus – B. adpressa hybrids a control of chromosome pairing seemed to exist. The possibility of amphidiploid plant production directly obtained in the F1 generation increased the risk of gene dispersal. The B. napus – B. oleracea amphidiploid plant presented a meiotic behavior more regular than that of the B. napus – S. arvensis amphidiploid plant. Concerning the herbicide bar gene characterization, the presence of the gene detected by DNA amplification was correlated with herbicide resistance, except for two plants. Different hypotheses were proposed to explain these results. A classification of the diploid species was established regarding their gene dispersal risk based on the rate of allosyndesis between chromosomes of AC genomes of rapeseed and the genomes of the related species.Key words: Brassicaceae, transgenic rapeseed, risk assessment, interspecific hybrids, chromosome pairing, bar gene characterization.

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.

Assessment of chromosome associations in haploids and their parental accessions in Hordeum

Genome ◽  
1988 ◽  
Vol 30 (2) ◽  
pp. 204-210 ◽  
Author(s):  
R. von Bothmer ◽  
N. C. Subrahmanyam
Keyword(s):  
Genetic Variation ◽  
Chromosome Pairing ◽  
Diploid Species ◽  
Meiotic Behaviour ◽  
Meiotic Pairing ◽  
Homoeologous Pairing ◽  
Homoeologous Chromosome ◽  
Homologous Pairing ◽  
Homoeologous Chromosome Pairing ◽  
Chromosome Associations

Meiotic pairing was studied in the following species and their haploid derivatives: Hordeum cordobense 2x, H. marinum 2x and 4x, H. secalinum 4x, H. capense 4x, H. jubatum 4x, H. brachyantherum 4x and 6x, H. lechleri 6x, and H. procerum 6x. The study revealed (i) homologous pairing in diploid species and very little nonhomologous associations in their mono-haploids; (ii) the alloploid nature of the polyploid taxa; (iii) a certain degree of homoeologous pairing in polyhaploids despite the diploid-like meiotic behaviour of the polyploids; (iv) genetic variation in the suppression of homoeologous chromosome pairing in different Hordeum species.Key words: Hordeum, meiotic pairing, haploids.

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