Suppression of homologous pairing between chromosomes of A and B genomes of 4x and 6x wheats by Hordeum californicum Covas and Stebbins

Genome ◽  
1988 ◽  
Vol 30 (1) ◽  
pp. 8-11
Author(s):  
H. S. Balyan ◽  
G. Fedak
Keyword(s):  
Chromosome Pairing ◽  
Chinese Spring ◽  
Chiasma Frequency ◽  
Mother Cell ◽  
Triticum Turgidum ◽  
Regulatory Gene ◽  
Intergeneric Hybrids ◽  
Homologous Pairing ◽  
Meiotic Analysis ◽  
Hybrid Plants

Three hybrids of Triticum turgidum cv. Ma with Hordeum californicum × T. aestivum cv. Chinese Spring amphiploid were obtained at a frequency of 1.6% of the pollinated florets. Meiotic analysis of the hybrid plants revealed an average chiasma frequency per pollen mother cell ranging from 15.27 to 17.60. The lower than expected chromosome pairing in the hybrid plants was attributed to the suppression of pairing between homologous wheat chromosomes by pairing regulatory gene(s) in H. californicum.Key words: intergeneric hybrids, Hordeum californicum, Triticum turgidum, meiosis, chromosome pairing.

Segregation in the pollen of F2 rye (Secale cereale) plants for induction of homoeologous chromosome pairing in hybrids with wheat (Triticum aestivum)

Genome ◽  
1987 ◽  
Vol 29 (6) ◽  
pp. 888-891 ◽  
Author(s):  
P. K. Gupta ◽  
G. Fedak
Keyword(s):  
Spring Wheat ◽  
Chromosome Pairing ◽  
Chinese Spring ◽  
Chiasma Frequency ◽  
Significant Variation ◽  
Intergeneric Hybrids ◽  
Homoeologous Chromosome Pairing ◽  
Chinese Spring Wheat ◽  
Pollen Plants ◽  
Partial Amphiploids

An attempt was made to determine the inheritance of the rye genes which induce high chiasma frequency in hybrids with wheat and to study if the ability of rye to induce partial amphiploidy in hybrids with wheat was heritable. Five to eight F2 pollen plants were derived from seeds taken from each of three F1 plants that had given high chiasma frequency in hybrids with 'Chinese Spring' wheat in earlier studies. Similarly, six to seven F2 pollen plants were derived from each of three F1 plants that had given partial amphiploids in hybrids with 'Chinese Spring' wheat in earlier studies. Chiasma frequency was studied in 127 hybrids with 'Chinese Spring' wheat. In the present study, significant differences in chiasma frequency were observed (i) among the 38 families represented by 127 plants, and (ii) between two groups of three sets each, one known for inducing high pairing and the other known for inducing partial amphiploidy associated with low pairing in wheat × F1 rye plants. Significant variation was also observed between families within sets (each originated from one F1 rye plant) suggesting that F2 rye plants derived from the same F1 plants also differed genetically for inducing heterogenetic (homoeologous) pairing in wheat × rye hybrids. One of the six sets particularly showed significantly higher pairing with a mean of 2.13 per cell (individual hybrids gave a chiasma frequency as high as a mean of 6.07 per cell) as against a range of 0.96 to 1.18 in the remaining five sets, suggesting accumulation of genes in F2 rye plants for inducing pairing in wheat × rye hybrids. It is expected that by intermating the segregating rye plants, it should be possible to accumulate genes and eventually to isolate homozygous lines inducing high pairing in hybrids with wheat. Contrary to expectation, no partial amphiploids were obtained in a study of 127 wheat × F2 rye hybrids, although three of the six F1 rye plants had earlier given partial amphiploids in wheat × F1 rye hybrids. Key words: intergeneric hybrids, wheat, rye, genetic control, chromosome pairing.

GENETIC VARIATION IN TRITICUM AFFECTING THE LEVEL OF CHROMOSOME PAIRING IN INTERGENERIC HYBRIDS

1970 ◽  
Vol 12 (2) ◽  
pp. 278-282 ◽  
Author(s):  
C. J. Driscoll ◽  
C. J. Quinn
Keyword(s):  
Triticum Aestivum ◽  
Genetic Variation ◽  
Natural Selection ◽  
Chromosome Pairing ◽  
Chinese Spring ◽  
Chiasma Frequency ◽  
Intergeneric Hybrids ◽  
Homoeologous Chromosome ◽  
Homoeologous Chromosome Pairing ◽  
Aegilops Variabilis

Genetic differences which affect the extent of homoeologous chromosome pairing in intergeneric hybrids have been demonstrated between varieties of Triticum aestivum. Each of seven varieties of Triticum was crossed with the same strain of Aegilops variabilis. Significant differences in chiasma frequencies between varieties were found. Varieties Eureka, Gamut and Chinese Spring constitute one group with a relatively low chiasma frequency and varieties A. R. Falcon, Federation and Poso constitute a distinct second group with a relatively high chiasma frequency. The variety Bearded Yalta is intermediate to the two groups. Thus, this genetic variation appears to be common among varieties of Triticum. Presumably this variation does not become subject to natural selection as long as chromosome pairing in the parental varieties remains strictly homologous.

Promotion of homoeologous chromosome pairing in hybrids of Triticum aestivum × Aegilops variabilis

Genome ◽  
1990 ◽  
Vol 33 (6) ◽  
pp. 825-828 ◽  
Author(s):  
S. Farooq ◽  
N. Iqbal ◽  
T. M. Shah
Keyword(s):  
Triticum Aestivum ◽  
Chromosome Pairing ◽  
Chinese Spring ◽  
Chiasma Frequency ◽  
Intergeneric Hybrids ◽  
Mutant Form ◽  
Homoeologous Pairing ◽  
Homoeologous Chromosome ◽  
Homoeologous Chromosome Pairing ◽  
Aegilops Variabilis

Intergeneric hybrids of Triticum aestivum variety Lu-26 and ph1b mutant of the cultivar Chinese Spring were produced with three accessions, A, B, and E, of Aegilops variabilis. Significant differences were found in the amount of homoeologous chromosome pairing at meiotic metaphase I. Hybrids between wheat variety Lu-26 and accessions A and B of Ae. variabilis showed very little pairing, as indicated by the chiasma frequency of 1.0 and 1.5 per cell, respectively. Hybrids between Lu-26 and accession E, on the other hand, showed significantly increased homoeologous pairing (mean chiasma frequency, 12.6/cell). The level of such pairing was essentially the same as that between the hybrids of ph1b 'Chinese Spring' × Ae. variabilis accessions A and B. However, when the ph1b mutant was hyridized with accession E, the level of chromosome pairing increased significantly (mean chiasma frequency, 17.52/cell). This is indicative of the presence of pairing promoter gene(s) in Ae. variabilis accession E, which are epistatic to the wheat Ph1 allele and positively interact with its mutant form to further increase the ph1b ceiling to homoeologous pairing in wheat.Key words: Triticum aestivum, ph1b mutant, Aegilops variabilis, intergeneric hybrids, homoeologous pairing.

EFFECT OF RYE ON HOMOEOLOGOUS CHROMOSOME PAIRING IN WHEAT × RYE HYBRIDS

1977 ◽  
Vol 19 (3) ◽  
pp. 549-556 ◽  
Author(s):  
J. Dvořák
Keyword(s):  
Triticum Aestivum ◽  
Chromosome Pairing ◽  
Chinese Spring ◽  
Triticum Aestivum L ◽  
Homoeologous Chromosome ◽  
Wheat Genotype ◽  
Hybrid Plants ◽  
Homoeologous Chromosome Pairing ◽  
Secale Cereale L ◽  
Polygenic System

The number of chiasmata per cell at metaphase I was scored in eight haploid plants of Triticum aestivum L. emend. Thell. cv. 'Chinese Spring' and 100 hybrid plants of Chinese Spring × Secale cereale L. Mean chiasma frequency per cell ranged from 0.00 to 3.59 in the hybrids and from 0.17 to 0.35 in the haploids. Since the same wheat genotype was present in both the haploids and hybrids, it is concluded that some of the rye genotypes promoted homoeologous chromosome pairing. The absence of distinct segregation classes among the hybrids suggests that these genes constitute a polygenic system.

Intergeneric hybrids between Hordeum vulgare and Elymus trachycaulus resistant to Russian wheat aphid

Genome ◽  
1991 ◽  
Vol 34 (6) ◽  
pp. 954-960 ◽  
Author(s):  
Taing Aung
Keyword(s):  
Hordeum Vulgare ◽  
Chromosome Pairing ◽  
Chromosome Doubling ◽  
Nuclear Gene ◽  
Russian Wheat Aphid ◽  
Intergeneric Hybrids ◽  
Hordeum Vulgare L ◽  
Elymus Trachycaulus ◽  
Hybrid Plants ◽  
Slender Wheatgrass

Intergeneric hybrids between cultivated barley (Hordeum vulgare L.) (2n = 2x = 14) and slender wheatgrass (Elymus trachycaulus (Link) Gould ex Shinners), PI 531691 (2n = 4x = 28), were produced. This slender wheatgrass accession carries resistance to Russian wheat aphid, Diuraphis noxia Mordvilko, and was used as pollen parent. The seven hybrid plants were also resistant to Russian wheat aphid. The hybrids were produced at a frequency of 0.21% of emasculated and hand-pollinated florets. Chromosome pairing in all the euploid hybrids was very low (average chiasma frequency per cell, 0.30). This indicates that the I genome from H. vulgare is remotely related to the SH genomes of E. trachycaulus. Expression of resistance to Russian wheat aphid in all the hybrid plants demonstrates that the nuclear gene or genes for insect resistance contributed by E. trachycaulus are either dominant or hemizygous effective. Five of the seven hybrid plants were vigorous and produced well-developed flowering spikes; however, they did not shed viable pollen. Since all the vegetatively cloned plants of these hybrids exhibited a high degree of perennial characteristics and could be induced to flower under a favourable light and temperature regime, they appear congenial for chromosome doubling and backcrossing. Preliminary observations suggest that successful backcrossing could be achieved using the F1 hybrids as pistillate parent and H. vulgare as pollen parent.Key words: Russian wheat aphid resistance, intergeneric hybrids, genomic relationship, chromosome pairing, Hordeum vulgare, Elymus trachycaulus.

THE EFFECT OF GENES CONTROLLING DIFFERENT DEGREES OF HOMOEOLOGOUS PAIRING ON QUADRIVALENT FREQUENCY IN INDUCED AUTOTETRAPLOID LINES OF TRITICUM LONGISSIMUM

1976 ◽  
Vol 18 (2) ◽  
pp. 357-364 ◽  
Author(s):  
Lydia Avivi
Keyword(s):  
Chromosome Pairing ◽  
Chiasma Frequency ◽  
Spatial Separation ◽  
Meiotic Pairing ◽  
Homoeologous Pairing ◽  
Homologous Pairing ◽  
Homologous Chromosomes ◽  
Chromosomal Pairing ◽  
Per Se ◽  
Quadrivalent Frequency

Different genotypes of Triticum longissimum are known to either promote or suppress chromosome pairing in crosses with polyploid wheats. Lines that promote homoeologous pairing are here designated as intermediate pairing lines, while those which have no such effect or suppress pairing are known as low pairing lines. To determine a possible effect of these genotypes on homologous pairing, tetraploidy was induced in both lines and chromosomal pairing was studied at first metaphase of meiosis. While the two induced autotetraploids did not differ in chiasma frequency or in the number of paired chromosomal arms, they differed significantly in multivalent frequency; the intermediate-pairing autotetraploid exhibited the same multivalent frequency as that expected on the basis of two telomeric initiation sites, while the low pairing autotetraploid exhibited a significantly lower frequency. It is assumed that in the autotetraploid the low pairing genotype does not affect meiotic pairing per se, but modifies the pattern of homologous association in a similar manner to that known in polyploids and caused by diploidization genes. It is speculated that the tendency for bivalent pairing in the low pairing autotetraploid is due to spatial separation of the four homologous chromosomes in somatic and premeiotic cells into two groups of two.

Cytology of intergeneric hybrids between Psathyrostachys and Elymus with Agropyron (Poaceae: Triticeae)

Genome ◽  
1992 ◽  
Vol 35 (4) ◽  
pp. 676-680 ◽  
Author(s):  
Kevin B. Jensen ◽  
Ira W. Bickford
Keyword(s):  
Chromosome Number ◽  
Chromosome Pairing ◽  
Intergeneric Hybrids ◽  
Agropyron Cristatum ◽  
Stainable Pollen ◽  
Meiotic Analysis ◽  
C Value ◽  
Elymus Species ◽  
I Cells ◽  
Metaphase I

This paper describes the cytogenetics and fertility of intergeneric hybrids of Psathyrostachys stoloniformis × Agropyron cristatum and two Elymus species, E. dentatus ssp. ugamicus and E. grandiglumis × A. cristatum. Bivalent frequencies of metaphase I cells in the F1 hybrid P. stoloniformis (NN) × Agropyron cristatum (PP) ranged from 0 to 4 per cell, with an average of 0.87 bivalent per cell and a c value of 0.07. The hybrid E. dentatus ssp. ugamicus (SSYY) × A. cristatum (PP) averaged 3.07 bivalents per cell and ranged from 0 to 7 with a c-value of 0.27. Bivalents were predominantly end to end associations. Meiotic analysis in E. grandiglumis (SSYYPP) × A. cristatum (PP) revealed an average of 6.84 bivalents per metaphase I cell with a c value of 0.73. This hybrid had a chromosome number of 2n = 30 rather than the expected 2n = 28. All hybrids had less than 1% stainable pollen and set no seed under open-pollination.Key words: chromosome pairing, meiosis.

Implications of chromosome pairing in a monohaploid and its colchidiploid of Solanum tuberosum (x = 12)

Genome ◽  
1988 ◽  
Vol 30 (3) ◽  
pp. 347-351 ◽  
Author(s):  
A. K. Singh ◽  
H. Uhrig ◽  
F. Salamini
Keyword(s):  
Solanum Tuberosum ◽  
Chromosome Pairing ◽  
Equatorial Plane ◽  
High Frequency ◽  
Mother Cell ◽  
Chromosome Complement ◽  
Meiotic Analysis ◽  
Parallel Orientation ◽  
Parent Clone ◽  
Pairing Behaviour

A monohaploid (x = 12) of Solanum tuberosum, its colchidiploid and their 2n parent clone have been cytologically examined. The meiotic analysis of the monoploid shows a certain degree of pairing at pachytene with a high frequency of bivalents at metaphase I. The bivalent frequency ranges from 2.07 to 3.0 per pollen mother cell (PMC). The most frequent classes are 3II + 6I and 2II + 8I. Several PMCs show secondary associations. At anaphase I (AI), the chromosomes distribute frequently in groups of 7 to 5 (32% of PMCs) and 6 to 6 (30% of PMCs). Occasionally, however, both disjunct chromosomes and univalents remain at the equatorial plane and divide with or without segregation, resulting in the formation of dyads or monads. The PMCs with a regular AI show a parallel orientation of spindles as well as a normal one, a situation that ends at telophase II with dyads, triads, and tetrads but 0% pollen fertility. The overall frequency of monads, dyads, triads, and tetrads is equal to 13, 69, 7 and 11%, respectively. Both in the parent clone and in the 2n colchidiploid clone, chromosome pairing is normal. The pairing behaviour in the monohaploid suggests the presence of duplicated sequences in the chromosome complement. An alteration of genes controlling the level of pairing is excluded.Key words: monohaploid, colchidiploid, chromosome pairing, meiosis.

Intergeneric hybrids between × Triticosecale cv. Welsh (2n = 42) and three genotypes of Agropyron intermedium (2n = 42)

1986 ◽  
Vol 28 (2) ◽  
pp. 176-179 ◽  
Author(s):  
P. K. Gupta ◽  
G. Fedak
Keyword(s):  
Pollen Mother Cell ◽  
Chromosome Pairing ◽  
Mother Cell ◽  
Intergeneric Hybrids ◽  
Agropyron Intermedium ◽  
Genome Homology ◽  
Paternal Parent

Three genotypes of Agropyron intermedium ssp. trichophorum (2n = 42) were crossed onto × Triticosecale cv. Welsh (2n = 42). Bivalent frequencies per pollen mother cell in the three hybrid combinations were 4.97, 5.64, and 6.94. Pairing was attributed to autosyndesis between two genomes (N and N1) of the paternal parent rather than to genome homology between the two parents.Key words: triticale, hybrids (intergeneric), chromosome pairing, × Triticosecale, agronomy.

Intergeneric hybrids between Triticum aestivum and three crested wheatgrasses: Agropyron mongolicum, A. michnoi, and A. desertorum

Genome ◽  
1990 ◽  
Vol 33 (5) ◽  
pp. 663-667 ◽  
Author(s):  
Qin Chen ◽  
Joseph Jahier ◽  
Yvonne Cauderon
Keyword(s):  
Triticum Aestivum ◽  
Chromosome Pairing ◽  
Adult Stage ◽  
Meiotic Chromosome ◽  
Intergeneric Hybrids ◽  
Species Hybrid ◽  
Hybrid Necrosis ◽  
Hybrid Plants ◽  
High Degree ◽  
First Time

Three hybridizations of Triticum aestivum cv. Chinese Spring (CS) (2n = 42) with Agropyron mongolicum (2n = 14), A. michnoi (2n = 28), and A. desertorum (2n = 28) are reported for the first time. Hybrid embryos were obtained at frequencies of 0.24, 1.13, and 2.05%, respectively. The hybrid plants obtained from pollinating CS by A. mongolicum had the expected chromosome number of 2n = 4x = 28, but as a result of hybrid necrosis, none could be raised to the adult stage. Hybrids CS × A. michnoi and CS × A. desertorum both had 2n = 5x = 35 chromosomes. The average meiotic chromosome pairing per cell was 7.04 I + 12.14 II + 1.06 III + 0.07 IV + 0.02 V + 0.02 VI and 9.29 I + 11.05 II + 1.14 III + 0.05 IV, respectively. Their analysis leads to the conclusions that (i) the two Agropyron genomes in the hybrids share a high degree of homology, thus revealing that tetraploid Agropyron species are true autoploids (genome constitution PPPP) and (ii) gene(s) in the Agropyron species suppress the activity of the homoeologous pairing control system of wheat. The possibility of gene transfer from Agropyron to wheat is discussed.Key words: intergeneric hybrids, Triticum aestivum, Agropyron species, hybrid necrosis, chromosome pairing.

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