scholarly journals MOST OF THE HOMOEOLOGOUS PAIRING AT METAPHASE I IN WHEAT-RYE HYBRIDS IS NOT CHIASMATIC

Genetics ◽  
1985 ◽  
Vol 111 (4) ◽  
pp. 917-931
Author(s):  
Juan Orellana
Keyword(s):  
Homoeologous Pairing ◽  
Homologous Pairing ◽  
End To End ◽  
Homoeologous Chromosomes ◽  
Metaphase I

ABSTRACT The use of telomeric C-bands in wheat-rye hybrids has made it possible to distinguish three types of wheat-wheat (1BL) and wheat-rye associations (a, end-to-end extremely distal; b, end-to-ed distal; and c, interstitial) between homoeologous chromosomes at different metaphase I stages (early, middle and late) and also to estimate the actual recombination frequencies for such associations at anaphase I. There was a decrease of the a and b association frequencies during the different metaphase I stages, whereas the c type remained without variation in all stages. A good fit between the frequencies of c associations at metaphase I and the number of recombinant chromosomes at anaphase I, assuming a maximum of one chiasma per bond, was found; however, there was no correspondence between metaphase I and anaphase I data when all associations (a + b + c) were considered. In addition, rye-rye homologous pairing was observed at metaphase I, but no evidence for rye-rye recombination was found at anaphase I. The results indicate that most of end-to-end (a and b) homoeologous and nonhomologous associations are actually nonchiasmatic and are a remnant of prophase pairing.

scholarly journals GENOME SIZE IN THREE SPECIES OF Glandularia AND THEIR HYBRIDS

2019 ◽  
Vol 30 (2) ◽  
pp. 47-54
Author(s):  
M.R. Ferrari ◽  
E.J. Greizerstein ◽  
L. Poggio
Keyword(s):  
Genome Size ◽  
Dna Content ◽  
High Frequency ◽  
Parental Species ◽  
The Other ◽  
F1 Hybrids ◽  
Homoeologous Pairing ◽  
The Relationship ◽  
Species Being ◽  
Homoeologous Chromosomes

In this work the relationship between genome size of Glandularia species and the meiotic configurations found in their hybrids are discussed. Glandularia incisa (Hook.) Tronc., growing in two localities of Corrientes and Córdoba provinces, Argentina, with different ecological conditions, showed inter-population variability of the 2C-value. The DNA content found in the Corrientes locality (2.41 pg) was higher than that obtained in the Córdoba locality (2.09 pg) which has more stressful environmental conditions than the former. These values are statistically different from those that were found in Glandularia pulchella (Sweet) Tronc. from Corrientes (1.43 pg) and in Glandularia perakii Cov. et Schn from Córdoba (1.47 pg). The DNA content of the diploid F1 hybrids, G. pulchella × G. incisa and G. perakii × G. incisa, differed statistically from the DNA content of the parental species, being intermediate between them. Differences in the frequency of pairing of homoeologous chromosomes were observed in the hybrids; these differences cannot be explained by differences in genome size since hybrids with similar DNA content differ significantly in their meiotic behavior. On the other hand, the differences in the DNA content between the parental species justify the presence of a high frequency of heteromorphic open and closed bivalents and univalents with different size in the hybrids. Key words: Intra-specific DNA content variability, homoeologous pairing, heteromorphic bivalents

COMPENSATED MONOSOMIC 5B-TRISOMIC 5A PLANTS IN TETRAPLOID WHEAT

1972 ◽  
Vol 14 (3) ◽  
pp. 463-475 ◽  
Author(s):  
T. Mello-Sampayo
Keyword(s):  
Tetraploid Wheat ◽  
Break Point ◽  
Suppressor Gene ◽  
Terminal Segment ◽  
Homoeologous Pairing ◽  
Homoeologous Group ◽  
Homologous Pairing ◽  
Antagonistic Effects ◽  
Aegilops Sharonensis ◽  
Group 5

Tetraploid wheat plants monosomic 5B-trisomic 5A were obtained by crossing nullisomic 5B-tetrasomic 5A plants of Triticum aestivum with T. durum and backcrossing five times with T. durum. These plants were found to carry a translocated 5A-5D chromosome. By self-pollination they originated plants carrying both a 5A-5D and 5B-5D translocated chromosome. In the latter the break point was located distally to the pairing suppressor gene. The translocations must have occurred by homoeologous pairing and recombination in the long arm of chromosomes of the group 5. F1 hybrids of monosomic 5B-trisomic 5A plants with rye and Aegilops sharonensis showed high homologous pairing when 5B was absent. Pairing promotion associated with the terminal segment of the long arm of 5D attached to the 5B-5D chromosome end was detected. It was suggested that the long arm of chromosomes of the homoeologous group 5 of wheat might carry two separate loci with genes for antagonistic effects on the pairing of chromosomes.

scholarly journals Wheat mutants permitting homoeologous meiotic chromosome pairing

1971 ◽  
Vol 18 (3) ◽  
pp. 311-328 ◽  
Author(s):  
A. M. Wall ◽  
Ralph Riley ◽  
Victor Chapman
Keyword(s):  
Triticum Aestivum ◽  
Chromosome Pairing ◽  
Secale Cereale ◽  
Meiotic Chromosome ◽  
Meiotic Pairing ◽  
Homoeologous Pairing ◽  
Homozygous Condition ◽  
Meiotic Chromosome Pairing ◽  
Homoeologous Chromosomes

SUMMARYPlants of Triticum aestivum (2n = 6x = 42) ditelocentric 5BL were treated with EMS in order to produce mutations in the 5B system by which meiotic pairing between homoeologous chromosomes is normally prevented. To check for the occurrence of mutation T. aestivum ditelo-5BL plants were pollinated with rye (Secale cereale 2n = 14) and meiosis was examined in the resulting hybrids.Wheat-rye hybrids were scored for the presence of mutants when the wheat parents were either the EMS-treated wheat plants, or their selfed derivatives, or their progenies obtained after pollination with untreated euploid individuals.Mutants were detected by each of these procedures and mutant gametes were produced by the treated ditelocentric plants with frequencies between 1·5 and 2·5%, but there were differences between the mutants in the extent to which homoeologous pairing occurred in the derived wheat-rye hybrids. The differences may have resulted from the occurrence of mutation at different loci or to different extents at the same locus.Two mutants, Mutant 10/13 and Mutant 61, were fixed in the homozygous condition. Mutant 10/13 was made homozygous both in the 5BL ditelocentric and in the euploid conditions but these genotypes regularly formed 21 bivalents at meiosis, and there was no indication of homoeologous pairing although the mutant 10/13 gave rise to homoeologous pairing in wheat-rye hybrids.

Homoeologous pairing and recombination between the long arms of group 1 chromosomes in wheat × rye hybrids

Genome ◽  
1989 ◽  
Vol 32 (2) ◽  
pp. 293-301 ◽  
Author(s):  
T. Naranjo ◽  
P. Fernández-Rueda ◽  
P. G. Goicoechea ◽  
A. Roca ◽  
R. Giráldez
Keyword(s):  
Banding Pattern ◽  
Homoeologous Pairing ◽  
Parental Type ◽  
C Banding ◽  
Group 1 Chromosomes ◽  
The Relationship ◽  
Double Recombinant ◽  
Group 1 ◽  
Metaphase I

The relationship between homoeologous pairing at metaphase I and recombination at anaphase I between the arms 1AL, 1BL, 1DL, and 1RL was analyzed in ph1b, 5B-deficient, and ph2b wheat × rye hybrids. All four arms could be identified at metaphase I, as well as the arms 1BL and 1RL at anaphase I, by means of C-banding. On the basis of the C-heterochromatin constitution that 1BL and 1RL showed at anaphase I and that association at metaphase I was essentially homoeologous, the following anaphase I chromosome types could be distinguished: parental type, single and double recombinant types between 1BL and 1AL or 1DL, between 1BL and 1RL, and between 1RL and 1AL or 1DL. Recombinant types 1AL – 1DL did not differ from the parental type for the C-banding pattern and was not considered. In the three genotypes, most if not all of 1BL – 1AL, 1BL – 1DL, and 1BL – 1RL metaphase I bonds were chiasmatic. 1RL – 1AL and 1RL – 1DL associations were scarce. Frequencies of one chiasma and two chiasmata for the arm combinations 1BL – 1AL plus 1BL – 1DL, 1BL – 1RL, and 1RL – 1AL plus 1RL – 1DL were estimated. Values decreased in the order ph1b, 5B-deficient, and ph2b hybrids.Key words: C-banding, chiasmata, homoeologues, anaphase I, ph genes.

scholarly journals Homoeologous pairing of a chromosome from Agropyron elongatum with those of Triticum aestivum and Aegilops speltoides

1967 ◽  
Vol 10 (1) ◽  
pp. 63-71 ◽  
Author(s):  
Roy Johnson ◽  
Gordon Kimber
Keyword(s):  
Triticum Aestivum ◽  
Average Rate ◽  
Aegilops Speltoides ◽  
Homoeologous Pairing ◽  
Agropyron Elongatum ◽  
Telocentric Chromosome ◽  
Telocentric Chromosomes ◽  
Group 6 ◽  
Genetic Compensation ◽  
Homoeologous Chromosomes

1. Complex hybrids were produced having twenty-nine chromosomes, consisting of one telocentric and twenty complete chromosomes of T. aestivum (2n = 6x = 42), seven complete chromosomes of Ae. speltoides (2n = 2x = 14) and one telocentric chromosome derived from A. elongatum (2n = 10x = 70). The presence of the Ae. speltoides genome permitted pairing between homoeologous chromosomes at meiosis and the behaviour of the two telocentric chromosomes was observed.2. The A. elongatum chromosome was seen to pair with chromosomes homoeologous to those of group 6. There was no evidence that it paired with chromosomes of any other group.3. When the A. elongatum telocentric and those of 6A and 6D occurred in the same configuration it was evident that the telocentrics 6A and 6D were for corresponding chromosome arms, and the A. elongatum telocentric for the opposite arm.4. The average rate of pairing was much lower for the A. elongatum telocentric than for wheat telocentrics. Previous studies had indicated very good genetic compensation of the A. elongatum chromosome for chromosomes 6A and 6D. It was therefore indicated that genetic equivalence and pairing affinity were not closely related in this case. Some implications of this are discussed.

scholarly journals The position of a locus on chromosome 5B of Triticum aestivum affecting homoeologous meiotic pairing

1971 ◽  
Vol 18 (3) ◽  
pp. 329-339 ◽  
Author(s):  
A. M. Wall ◽  
Ralph Riley ◽  
M. D. Gale
Keyword(s):  
Triticum Aestivum ◽  
Chromosome Pairing ◽  
Single Locus ◽  
Meiotic Pairing ◽  
Homoeologous Pairing ◽  
Chromosome 5B ◽  
Homoeologous Chromosome Pairing ◽  
Mutant Locus ◽  
Homoeologous Chromosomes ◽  
Pairing Behaviour

SUMMARYAn investigation was made of the chromosomal position of the mutant locus, in Mutant 10/13 of Triticum aestivum (2n = 6x = 42), affecting homoeologous chromosome pairing at meiosis. In hybrids between Mutant 10/13 and rye (Secale cereale 2n = 14), homoeologous chromosomes frequently pair at meiosis although normally, in wheat-rye hybrids, this happens infrequently.The association of the mutant condition with chromosome 5B was determined by (i) the absence of segregation in hybrids obtained when Mutant 10/13 monosomic 5B was pollinated by rye; (ii) the occurrence of trisomie segregation for pairing behaviour in 28-chromosome wheat-rye hybrids, obtained from SB trisomie wheat parents with two 5B chromosome from a non-mutant and one from a mutant parent; (iii) the absence of segregation for pairing behaviour in the 29-chromosome wheat-rye hybrids obtained from the same trisomie wheat parents.The alternative pairing behaviours segregated independently of the centromere when wheat plants that were simultaneously heteromorphic, 5BL telocentric/5B complete, and heterozygous for the Mutant 10/13 state, were pollinated by rye. The alternative chromosome-pairing patterns segregated to give a ratio not different from 1:1, so that the association of homoeologous pairing with Mutant 10/13 probably derived from the occurrence of mutation at a single locus on 5BL. In the disomic heteromorphic state, 5BL was 91 map units in length.Trisomie wheats with two complete 5B chromosomes and one 5BL telocentric, that were also heterozygous for the Mutant 10/13 condition, were pollinated by rye. Among the resulting 28-chromosome hybrids there was a 2:1 segregation of hybrids with low pairing: high (homoeologous) pairing and also of hybrids with complete 5B: telocentric 5BL. However, there was no evidence of linkage in this trisomie segregation. All the 29-chromosome hybrids from this cross had low pairing and it could be concluded that the single mutant allele, in Mutant 10/13, was recessive. In the trisomie condition, relative to a simplex situation, 5BL was 33·05 map units in length.The critical locus on 5BL was designated Pairing homoeologous. The normal dominant allele was symbolized Ph and the recessive allele, in Mutant 10/13, ph.The prevention of homoeologous pairing by the activity of a single locus makes the evolution of the regular meiotic behaviour of T. aestivum more readily comprehensible.

scholarly journals Timing imbalance in the meiosis of the F1 hybrid Oryza sativa × O. australiensis

1961 ◽  
Vol 2 (3) ◽  
pp. 373-383 ◽  
Author(s):  
S. V. S. Shastry ◽  
D. R. Ranga Rao
Keyword(s):  
Oryza Sativa ◽  
Comparative Morphology ◽  
Meiotic Pairing ◽  
F1 Hybrid ◽  
Oryza Saliva ◽  
End To End ◽  
Primitive Member ◽  
Meiotic Cycle ◽  
Metaphase I

The meiosis in the F1 hybrid Oryza saliva × O. australiensis was studied. Contrary to the observations of Gopalakrishnan (1959), true allosyndetic bivalents were not found at metaphase I. The most frequent associations were non-chiasmatic, end-to-end pseudobivalents. Autosyndetic bivalents were recorded mostly in the complement belonging to O. sativa, which are distinguishable by their smallness and lighter staining. The meiotic cycle exhibits timing imbalance with earlier condensation, and possibly migration, of the univalents belonging to O. australiensis. The data on meiotic pairing in the F1 hybrid and the comparative morphology of O. sativa, O. officinalis and O. australiensis inicate that the last species is the most primitive member, having originated from the pre-Sativa and pre-Officinalis complex.

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.

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.

Trigenomic combinations for the analysis of meiotic control in the cultivated Brassica species

Genome ◽  
1987 ◽  
Vol 29 (2) ◽  
pp. 331-333 ◽  
Author(s):  
C. Busso ◽  
T. Attia ◽  
G. Röbbelen
Keyword(s):  
Meiotic Recombination ◽  
Genetic Factor ◽  
Brassica Campestris ◽  
Brassica Species ◽  
Homoeologous Pairing ◽  
Cytological Evidence ◽  
Cytoplasmic Effects ◽  
B Genome ◽  
Successful Transfer ◽  
Homoeologous Chromosomes

Haploid hybrids of either Brassica campestris (AA) or B. oleracea (CC) with B. nigra (BB) show a relatively low amount of chromosome pairing as compared with the level observed in the hybrid B. campestris × B. oleracea. This finding led to assume that B. nigra may carry a genic system suppressing homoeologous pairing in Brassica. To test this hypothesis, trigenomic hybrids (genome constitution ABC, 2n = 27) were synthesized, in which the effect of the B genome on the homoeologous pairing of the A and C genomes could be measured. The results indicate the inability of B. nigra to affect the level of pairing between homoeologous chromosomes of the A and C genomes. No genetic factor for a suppression of pairing was found in the B genome and there were no cytoplasmic effects on the regulation of pairing. However, cytological evidence pointed to chances of a successful transfer of economically valuable genes from B. nigra into the A and C genomes through the normal events of meiotic recombination. Key words: Brassica, triploid (trigenomic), homoeologous pairing, gene transfer.

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