FERTILITY AND MEIOTIC BEHAVIOUR IN TETRAPLOID BARLEY

1975 ◽  
Vol 17 (1) ◽  
pp. 121-123 ◽  
Author(s):  
George Fedak
Keyword(s):  
Chromosome Pairing ◽  
Meiotic Behaviour ◽  
Preferential Pairing ◽  
Subsequent Fertility ◽  
Structural Differences ◽  
Hordeum Leporinum ◽  
Metaphase I

Chromosome pairing at metaphase I and distribution at anaphase I were examined in 3 autotetraploid and 3 amphidiploid parents and their F1 hybrids and related to spike fertility of the respective plants. Structural differences translocated from the Hordeum leporinum chromosomes to H. vulgare did not significantly enhance preferential pairing and subsequent fertility in the latter as anticipated. Quadrivalent formation was not related but regular disjunction at anaphase I was related to spike fertility.

Chromosome pairing in hybrids of ph1b mutant wheat with rye

Genome ◽  
1988 ◽  
Vol 30 (5) ◽  
pp. 639-646 ◽  
Author(s):  
T. Naranjo ◽  
A. Roca ◽  
R. Giraldez ◽  
P. G. Goicoechea
Keyword(s):  
Common Wheat ◽  
Chromosome Pairing ◽  
Chromosome Structure ◽  
Preferential Pairing ◽  
C Banding ◽  
Homoeologous Chromosomes ◽  
Metaphase I

Metaphase I pairing was studied in five ph1b mutant wheat × rye hybrids to verify the presence of translocations between homoeologous chromosomes in ph1b mutant wheat and to establish the pairing homoeology between wheat and rye chromosomes. Three 5B-deficient ABDR hybrids with standard chromosome structure were used as controls. Chromosomes 1R and 5R of rye and most wheat chromosomes, as well as their arms, were identified by means of C-banding. The presence of 5BS in ph1b hybrids raised the overall pairing level. The pattern of pairing between wheat chromosomes in ph1b hybrids, as in 5B-deficient hybrids, was characterized by the occurrence of preferential pairing between chromosomes of the A and D genomes in most homoeologous groups. The existence of a double translocation involving 4BL, 5AL, and 7BS in common wheat was confirmed. Deviation from the standard pairing pattern suggested the existence of a translocation involving 1BL and 1DL in one ph1b ABDR plant and another translocation involving 3AL and 3DL in three other ph1b hybrids. In ph1b hybrids, wheat – rye pairing was relatively frequent for 1RL, 5RL, and an arm of a metacentric rye chromosome, probably 2R, that is homoeologous to 2BL, and the homoeologous arms of 2A and 2D. The existence of a translocation involving 5RL and 4RL in rye was confirmed.Key words: homoeologous, homologous, 5B-deficient, translocations, C-banding.

CYTOLOGY OF PASPALUM VIRGATUM AND ITS RELATIONSHIP WITH P. INTERMEDIUM AND P. JURGENSII

1982 ◽  
Vol 24 (2) ◽  
pp. 219-226 ◽  
Author(s):  
Byron L. Burson ◽  
Camilo L. Quarin
Keyword(s):  
Chromosome Pairing ◽  
Cytological Study ◽  
Structural Differences ◽  
Metaphase I

A cytological study revealed that Paspalum virgatum L. is sexual, meiotically stable, and has 2n = 4x = 40 chromosomes. Paspalum virgatum was crossed with P. intermedium Munro. ex Morong and P. jurgensii Hackel; both have 2n = 2x = 20 chromosomes. Six P. intermedium × P. virgatum, 2n = 3x = 30, hybrids were studied cytologically. Meiosis was irregular with a mean chromosome pairing of 11.68 univalents, 9.09 bivalents, 0.03 trivalents, and 0.002 quadrivalents per cell at metaphase I. This indicates that the two species have a homologous genome with some minute structural differences because some of the bivalents were not tightly synapsed. One hybrid, 2n = 3x = 30, was recovered from the P. jurgensii × P. virgatum cross. Meiosis was irregular with a mean pairing of 18.72 univalents, 5.70 bivalents, and 0.05 trivalents. These findings suggest that P. jurgensii and P. virgatum have a partially homologous genome. Because P. intermedium and P. jurgensii have the genome formulas II and JJ, respectively, the formula II J2J2 is proposed for P. virgatum.

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.

Chromosome pairing affinity and quadrivalent formation in polyploids: do segmental allopolyploids exist?

Genome ◽  
1996 ◽  
Vol 39 (6) ◽  
pp. 1176-1184 ◽  
Author(s):  
J. Sybenga
Keyword(s):  
Key Words ◽  
Chromosome Pairing ◽  
Meiotic Behaviour ◽  
Homoeologous Pairing ◽  
Preferential Pairing ◽  
Multivalent Formation ◽  
Well Differentiated ◽  
Quadrivalent Frequency ◽  
Segmental Allopolyploid ◽  
Clear Cases

When polyploid hybrids with closely related genomes are propagated by selfing or sib-breeding, the meiotic behaviour will turn into essentially autopolyploid behaviour as soon as the affinity between the genomes is sufficient to permit occasional homoeologous pairing. An allopolyploid will only be formed when the initial differentiation is sufficient to completely prevent homoeologous pairing (in some cases enhanced by specific genes), or when segregational dysgenesis prevents transmission of recombined chromosomes. A new polyploid hybrid may be considered a segmental allopolyploid and may show reduced multivalent formation as a result of preferential pairing between the least differentiated genomes. An established polyploid is either an autopolyploid or an allopolyploid. In exceptional cases it is thinkable that a stable segmental allopolyploid arises, in which some sets of chromosomes are well differentiated and behave as in an allopolyploid, whereas other sets are not well differentiated and behave as in an autopolyploid. No clear cases have been found in the literature so far. Key words : chromosome, pairing affinity, quadrivalent frequency, segmental allopolyploidy.

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.

Chromosome pairing and potential for intergeneric recombination in some hypotetraploid somatic hybrids of Lycopersicon esculentum (+) Solanum tuberosum

Genome ◽  
1993 ◽  
Vol 36 (6) ◽  
pp. 1032-1041 ◽  
Author(s):  
J. H. de Jong ◽  
A. M. A. Wolters ◽  
J. M. Kok ◽  
H. Verhaar ◽  
J. van Eden
Keyword(s):  
Solanum Tuberosum ◽  
Lycopersicon Esculentum ◽  
Synaptonemal Complex ◽  
Chromosome Pairing ◽  
Somatic Hybrids ◽  
Cytogenetic Study ◽  
Unreduced Gametes ◽  
Root Tip ◽  
Prophase I ◽  
Metaphase I

Three somatic hybrids resulting from protoplast fusions of a diploid kanamycin-resistant line of tomato (Lycopersicon esculentum) and a dihaploid hygromycin-resistant transformant of a monohaploid potato (Solanum tuberosum) line were used for a cytogenetic study on chromosome pairing and meiotic recombination. Chromosome counts in root-tip meristem cells revealed two hypotetraploids with chromosome complements of 2n = 46 and one with 2n = 47. Electron microscope analyses of synaptonemal complex spreads of hypotonically burst protoplasts at mid prophase I showed abundant exchanges of pairing partners in multivalents involving as many as eight chromosomes. In the cells at late pachytene recombination nodules were found in multivalents on both sides of pairing partner exchanges, indicating recombination at both homologous and homoeologous sites. Light microscope observations of pollen mother cells at late diakinesis and metaphase I also revealed multivalents, though their occurrence in low frequencies betrays the reduction of multivalent number and complexity. Precocious separation of half bivalents at metaphase I and lagging of univalents at anaphase I were observed frequently. Bridges, which may result from an apparent inversion loop found in the synaptonemal complexes of a mid prophase I nucleus, were also quite common at anaphase I, though the expected accompanying fragments could be detected in only a few cells. Most striking were the high frequencies of first division restitution in preparations at metaphase II/anaphase II, giving rise to unreduced gametes. In spite of the expected high numbers of balanced haploid and diploid gametes, male fertility, as revealed by pollen staining, was found to be negligible.Key words: synaptonemal complex, recombination, chromosome pairing, somatic hybrid, Lycopersicon esculentum (+) Solanum tuberosum.

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.

Analysis of synaptonemal complexes and chromosome pairing at metaphase I in the diploid intergeneric hybrid Lolium multiflorum × Festuca drymeja

Genome ◽  
1990 ◽  
Vol 33 (4) ◽  
pp. 465-471 ◽  
Author(s):  
Hum M. Thomas ◽  
W. G. Morgan
Keyword(s):  
Chromosome Pairing ◽  
Complex Analysis ◽  
Lolium Multiflorum ◽  
Intergeneric Hybrid ◽  
Chiasma Formation ◽  
Genotypic Effect ◽  
Synaptonemal Complexes ◽  
Dna Values ◽  
Synaptonemal Complex Analysis ◽  
Metaphase I

The synaptonemal complexes in the diploid hybrid Lolium multiflorum × Festuca drymeja were examined by the surface spreading technique, and chromosome pairing at metaphase I was analysed. Synaptonemal complex analysis revealed "illegitimate" pairing, including multivalents and foldback pairing. At metaphase I, most chiasmata were between chromosomes of the same genome, and again multivalents were found. It was concluded that most synaptonemal complexes resulted in chiasma formation. The effects of the large differences in DNA values of the two species and the possible genotypic effect of F. drymeja on chromosome pairing are discussed.Key words: Lolium-Festuca, synaptonemal complexes, nonhomologous pairing, DNA values.

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