CHROMOSOME ASSOCIATIONS AT DIAKINESIS IN THE CULTIVATED STRAWBERRY

1971 ◽  
Vol 13 (2) ◽  
pp. 231-236 ◽  
Author(s):  
D. W. S. Mok ◽  
W. D. Evans
Keyword(s):  
Chromosome Pairing ◽  
Genetic Data ◽  
Cytological Evidence ◽  
Tetrasomic Inheritance ◽  
Secondary Pairing ◽  
Multivalent Formation ◽  
Chromosome Associations

The analysis of chromosome pairing in the cultivated strawberry revealed that multivalent formation occurs in each of the nine cultivars examined. Secondary pairing and a loose association of bivalents were also observed. The cytological evidence suggests that tetrasomic inheritance should be considered in the interpretation of genetic data.

Investigations in the Triticinae II. The cytology and fertility of intergeneric and interspecific F1 hybrids and their derived amphidiploids

1953 ◽  
Vol 43 (1) ◽  
pp. 105-115 ◽  
Author(s):  
G. D. H. Bell ◽  
Leo Sachs
Keyword(s):  
Chromosome Pairing ◽  
Intergeneric Hybrids ◽  
F1 Hybrids ◽  
Cytological Evidence ◽  
Structural Chromosome ◽  
Multivalent Formation ◽  
Bivalent Formation ◽  
Low Incidence ◽  
High Degree ◽  
Differential Affinity

1. Chromosome pairing has been studied in twenty-two different sterile F1 hybrids involving the genera Aegilops, Agropyron and Triticum, together with their colchicine derived amphidiploids having chromosome numbers of 2n = 42, 56 and 70. Cytological evidence has been correlated with male and female fertility, while chromosome pairing in the parents has been studied in relation to their amphidiploids.2. Some of the sterile F1 hybrids showed little or no pairing, while in others the pairing was appreciable. There was an association of the amount of pairing with the parental combinations used in the production of the hybrids in that the interspecific hybrids were characterized by a relatively high degree of pairing, particularly those with 28 chromosomes, while the intergeneric hybrids either lacked pairing or showed a low incidence.3. In the A1 amphidiploid generation, chromosome pairing was in all cases high, and in some cases almost complete. In all cases multivalent formation in the amphidiploid was lower than bivalent formation in its undoubted F1 hybrid. Different amphidiploids showed various degrees of differential affinity. Univalent formation occurred in some amphidiploids, while bivalent formation in some was increased by a loss of chromosomes.4. In all cases there was a reduction in chiasmata per nucleus and chiasmata per bivalent in the amphidiploid compared with its parent species. Reduction values were not directly associated with any increase in chromosome number of the amphidiploid, nor with the presence of multivalents.5. No confirmation could be obtained of the view that multivalent formation in amphidiploids is a more generally sensitive index of chromosome homology than bivalent formation in the undoubted F1 hybrid. The absence of multivalents in an amphidiploid does not disprove the existence of structural chromosome homologies between the two parents.

Tetrasomic inheritance and chromosome pairing behaviour in the naturally occurring autotetraploid Heuchera grossulariifolia (Saxifragaceae)

Genome ◽  
1989 ◽  
Vol 32 (4) ◽  
pp. 655-659 ◽  
Author(s):  
Paul G. Wolf ◽  
Pamela S. Soltis ◽  
Douglas E. Soltis
Keyword(s):  
Chromosome Pairing ◽  
Meiotic Chromosome ◽  
Low Frequency ◽  
Small Chromosome ◽  
Tetrasomic Inheritance ◽  
Naturally Occurring ◽  
Chromatid Segregation ◽  
Marker Loci ◽  
Allozyme Loci ◽  
Pairing Behaviour

Inheritance patterns at four allozyme loci and chromosome pairing behaviour at diakinesis were examined in the naturally occurring autotetraploid Heuchera grossulariifolia. Segregation patterns for Tpi, Pgi, Pgm-2, and Lap deviated significantly from all possible disomic models. All patterns were consistent with tetrasomic inheritance of these marker loci. No chromatid segregation was detected electrophoretically. Meiotic chromosome configurations at diakinesis in 45 cells were compared with a previously published model to test for autopolyploid-like chromosome pairing. Using the observed chiasma frequencies, the frequency of quadrivalents was consistent with the expectations for an autotetraploid. We suggest that the low frequency of quadrivalents at diakinesis in Heuchera grossulariifolia is due to small chromosome size, which results in a low chiasma frequency.Key words: autopolyploidy, tetrasomic inheritance, chromosome pairing, isozyme genetics, Heuchera.

Cytogenetics of decaploid Agropyron elongatum (Elytrigia elongata) (2n = 70). I. Frequency of decavalent formation

Genome ◽  
1990 ◽  
Vol 33 (6) ◽  
pp. 811-817 ◽  
Author(s):  
Mikio Muramatsu
Keyword(s):  
High Frequency ◽  
Chromosome Association ◽  
Agropyron Elongatum ◽  
Homologous Chromosomes ◽  
Ring Shape ◽  
Meiotic Configuration ◽  
Multivalent Formation ◽  
A Cell ◽  
Chromosome Associations ◽  
Metaphase I

The multivalents that appeared in the decaploid strain of Agropyron elongatum (2n = 10x = 70), a relative of wheat, ranged from trivalent to decavalent. Few univalents occurred. The metaphase I chromosome association in 12 cells where all configurations could clearly be identified averaged 0.42 ring X + 0.17 chain X + 0.42 ring VIII + 0.17 branched VIII + 0.25 chain VIII + 0.17 chain VII + 1.17 ring VI + 0.33 branched VI + 0.5 chain VI + 1.67 ring IV + 0.42 branched IV + 0.58 chain IV + 0.08 branched III + 0.17 chain III + 12.58 ring II + 3.75 open II + 0.25 I. The occurrence of decavalents, up to two in one cell, and of a cell with five multivalents, each of which involved more than five chromosomes, and many multivalents of ring shape indicated that the strain is autodecaploid.The chromosome associations of each cell can be interpreted as seven groups of 10 homologous chromosomes. The high frequency of bivalents indicated a tendency toward reduced multivalent formation, for which an explanation is suggested.Key words: Agropyron elongatum, meiotic configuration, decaploid, multivalent.

THE CYTOGENETIC STRUCTURE OF A 56-CHROMOSOME DERIVATIVE FROM A CROSS BETWEEN TRITICUM AESTIVUM AND AGROPYRON ELONGATUM (2n = 70)

1976 ◽  
Vol 18 (2) ◽  
pp. 271-279 ◽  
Author(s):  
Jan Dvořák
Keyword(s):  
Triticum Aestivum ◽  
Chromosome Pairing ◽  
Chinese Spring ◽  
Wheat Chromosome ◽  
Agropyron Elongatum ◽  
Synthetic Genome ◽  
Chromosome Associations ◽  
Chromosome Segments ◽  
The Relationship ◽  
Chromosome 3B

Chromosome pairing was studied in a number of hybrids involving a 56-chromosome wheat-Agropyron derivative, PW 327. PW 327 originated from the cross, Triticum aestivum cv. Chinese Spring (Chinese Spring × A. elongatum, 2n = 70). In hybrids between PW 327 and T. aestivum a number of multivalent chromosome associations were formed at metaphase I. These multivalents result from interchanges which occurred among wheat chromosomes 1A, 1D, 2A, 2D, 4D and 6D of PW 327. One chromosome of the Agropyron chromosome set of PW 327 occasionally pairs with wheat chromosome 3B. The rest of the Agropyron chromosomes present in PW 327 do not pair with the chromosomes of T. aestivum. It is proposed that the set of Agropyron chromosomes present in PW 327 is not an intact genome of decaploid A. elongatum but rather a modified synthetic genome combining chromosomes and/or chromosome segments from different genomes of the Agropyron parent. The incorporation of duplication-deletions into synthetic genomes of natural polyploids is discussed and it is shown that the set of Agropyron chromosomes which is present in PW 327 carries at least one such duplication-deletion. Pairing between chromosomes of diploid and decaploid A. elongatum was studied in a 56-chromosome hybrid from a cross between an amphiploid, T. aestivum × A. elongatum (2n = 14), and PW 327. It appeared that at least four chromosomes of these two Agropyrons occasionally paired with each other in this hybrid in which the diploidizing system of wheat was active. The relationship between chromosomes of diploid and decaploid A. elongatum is discussed.

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.

The initiation of meiotic chromosome pairing: the cytological view

Genome ◽  
1990 ◽  
Vol 33 (6) ◽  
pp. 759-778 ◽  
Author(s):  
Josef Loidl
Keyword(s):  
Synaptonemal Complex ◽  
Chromosome Pairing ◽  
Meiotic Chromosome ◽  
Meiotic Pairing ◽  
Cytological Evidence ◽  
Homologous Chromosomes ◽  
Synaptonemal Complex Formation ◽  
Meiotic Synapsis ◽  
The One ◽  
First Contact

Opposing views are held with respect to the time when and the mechanisms whereby homologous chromosomes find each other for meiotic synapsis. On the one hand, some evidence has been presented for somatic homologous associations or some other kind of relationship between chromosomes in somatic cells as a preliminary to meiotic pairing. On the other hand, it is argued by many that homologous contacts are first established at meiotic prophase prior to, or in the course of, synaptonemal complex formation. The present paper reviews the controversial cytological evidence, hypotheses, and ideas on how the first contact between homologous chromosomes comes about.Key words: synapsis, meiosis, presynaptic alignment, homologous recognition, synaptonemal complex, chromosome pairing.

FUSION OF CHROMOCENTERS IN PREMEIOTIC INTERPHASE OF SECALE CEREALE AND ITS POSSIBLE RELATIONSHIP TO CHROMOSOME PAIRING

1977 ◽  
Vol 19 (2) ◽  
pp. 313-321 ◽  
Author(s):  
J. G. Bowman ◽  
Tibor Rajhathy
Keyword(s):  
Chromosome Pairing ◽  
Secale Cereale ◽  
Disruptive Effect ◽  
Immature Inflorescence ◽  
Multivalent Formation ◽  
Relationship Of ◽  
The Relationship ◽  
Metaphase I

The premeiotic interphase of rye has been found to exhibit a synchronized fusion of chromocenters. This results in a solid knot of heterochromatin localized to one side of the nucleus. Colchicine injected into the immature inflorescence of diploid rye has been found to induce univalent and multivalent formation at metaphase I. The early premeiotic interphase was the phase of development most sensitive to colchicine. Colchicine was also found to have a similar disruptive effect on fusion of chromocenters in the premeiotic interphase. The relationship of these observations to chromosome pairing is discussed.

CHROMOSOME RELATIONSHIPS AND MORPHOLOGICAL COMPARISONS BETWEEN THE DIPLOID OATS AVENA PROSTRATA, A. CANARIENSIS AND THE TETRAPLOID A. MAROCCANA

1980 ◽  
Vol 22 (2) ◽  
pp. 287-294 ◽  
Author(s):  
J. M. Leggett
Keyword(s):  
Chromosome Pairing ◽  
Cytological Evidence ◽  
Geographical Data ◽  
Tetraploid Hybrid ◽  
A Genome

The morphology and chromosome pairing of the triploid hybrids Avena canariensis Baum, Rajhathy et Sampson × A. maroccana Gdgr., A. prostrata Ladiz × A. maroccana, the diploid A. prostrata and the tetraploid derived between A. prostrata and A. canariensis and the tetraploid hybrid between this derived tetraploid and A. maroccana are described in relation to genomic affinities between these species. The cytological evidence is at variance with morphological and geographical data which initially indicated that A. canariensis was the donor of the A genome of the A. maroccana-A. murphyi group of tetraploids. The possible relationship between the species is briefly discussed.

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