The effect of the Ph1 gene in diploid rye, Secale cereale L.

Genome ◽  
1991 ◽  
Vol 34 (6) ◽  
pp. 913-917 ◽  
Author(s):  
R. Schlegel ◽  
A. Boerner ◽  
V. Thiele ◽  
G. Melz
Keyword(s):  
Chromosome Pairing ◽  
Chiasma Frequency ◽  
Addition Line ◽  
Homologous Pairing ◽  
Chromosome 5B ◽  
Secale Cereale L ◽  
Ph1 Locus ◽  
Ph1 Gene ◽  
Bivalent Formation ◽  
Octoploid Triticale

Experimental results demonstrated clearly that the dominant Ph1 allele of chromosome 5B of wheat affects the homologous pairing of rye chromosomes. A rye-wheat monotelosomic 5BL addition line was produced and used for meiotic studies. Compared with 14-chromosome control plants, the 5BL addition to rye causes an increase in univalents and rod bivalent formation, i.e., a significant reduction of chiasma frequency (11.21 chiasmata per pollen mother cell). The 5BL telosome itself does not associate with any of the rye chromosomes. Thus, the double dosage of 5BL, present in hexaploid or octoploid triticale, could be one of the main causes of pairing failure of the rye genome.Key words: chromosome pairing, Ph1 locus, wheat, rye, rye-wheat addition.

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.

THE SIGNIFICANCE OF MEIOTIC CHROMOSOME PAIRING IN TETRAPLOID (2n = 28) BROMUS PUMPELLIANUS SCRIBN. SSP. DICKSONII

1972 ◽  
Vol 14 (4) ◽  
pp. 763-771 ◽  
Author(s):  
K. C. Armstrong
Keyword(s):  
Chromosome Pairing ◽  
High Frequency ◽  
Chiasma Frequency ◽  
Karyotype Analysis ◽  
Meiotic Chromosome ◽  
Low Frequency ◽  
Meiotic Chromosome Pairing ◽  
Ring Bivalents ◽  
Bivalent Formation

Bivalent formation was predominant at meiosis in B. pumpellianus ssp. dicksonii. The average in 15 plants ranged from 11.38 to 13.77 bivalents per cell. The high chiasma frequency (23.41-26.74) was a reflection of the high frequency of ring bivalents (9.48-12.42). A low frequency of quadrivalents occurred (0.06-1.22). A karyotype of this species was presented from both a highly contracted and moderately contracted cell and the differences between these two were noted. Four satellites were found, two large and two minute. There were 3-5 submedian and 5-7 median chromosomes depending on the cell studied. In addition two subterminal chromosomes were present. The meiotic and karyotype analysis suggest a deviation from an autotetraploid behaviour, but the presence of quadrivalents and similarities between pairs in the karyotype suggested closely related genomes. Alternatively it was considered that the quadrivalents could be due to translocation heterozygotes. The implications of these results were discussed in relation to the reported meiotic events in the octoploids, B. inermis and B. pumpellianus.

Location of the Ph1 locus in the metaphase chromosome map and the linkage map of the 5Bq arm of wheat

1986 ◽  
Vol 28 (4) ◽  
pp. 511-519 ◽  
Author(s):  
R. Jampates ◽  
J. Dvořák
Keyword(s):  
Linkage Map ◽  
Chromosome Pairing ◽  
Chinese Spring ◽  
Chromosome Rearrangement ◽  
Distal Region ◽  
Crossing Over ◽  
Chromosome 5B ◽  
Ph1 Locus ◽  
The Difference ◽  
Two Populations

Heterogenetic chromosome pairing in wheat is prevented by the Ph1 locus on the q (=L) arm of chromosome 5B. Two durum wheat cv. Cappelli structural mutants with rearranged 5Bq chromosome arms were investigated to determine the location of the Ph1 locus in the metaphase map and the linkage map of the arm. One of the mutants, Cap5Bq−, has a deletion of subregion 5Bq12.3 between C-bands 5Bq12.2 and 5Bq21 and the other one, Cap5Bq+, has the same subregion duplicated. Each mutant and standard cv. Cappelli were crossed with Aegilops kotschyi, Ae. ovata, Ae. cylindrica, Ae. ventricosa, Ae. juvenalis, and "Ae. crassa 6x." Hybrids involving Cap5Bq− had higher levels of chromosome pairing than those involving cv. Cappelli, whereas those involving Cap5Bq+ had lower levels of pairing than those involving cv. Cappelli. Cap5Bq− was crossed with cv. Cappelli and the F1 was hybridized with Ae. kotschyi and Ae. ventricosa. All hybrids with the 5Bq− chromosome had a higher level of chromosome pairing than those with the standard chromosome. Cap5Bq+ was crossed with cv. Cappelli and the F1 was hybridized with Ae. kotschyi. Most hybrids with the 5Bq+ chromosome had a lower level of chromosome pairing than those with the standard chromosome. Because the difference between the means of the two populations was small (0.43 chiasmata per cell) and the distributions overlapped, the strength of the linkage between the duplication and reduced pairing could not be determined; the data, nevertheless, showed that the reduced pairing must be strongly, if not completely, linked to the duplication. It is therefore concluded that the Ph1 locus is in the euchromatic subregion 5Bq12.3, 5Bq− is a null for Ph1, and 5Bq+ has two Ph1 loci. The 5Bq+ chromosome was substituted into Triticum aestivum cv. Chinese Spring, the substitution was crossed with cv. Chinese Spring ditelosomic 5Bq, and the F1 was crossed with cv. Chinese Spring monosomic 5B. Recombination of C-bands relative to each other and the centromere was determined with the objective of determining the distribution of crossing-over along the 5Bq arm and the linkage of the subregion 5Bq12.3 with the centromere. The distibution of crossing-over was greatly distorted, most occurred in the distal region of the arm. The subregion 5Bq12.3 showed a tight linkage with the centromere, even though it is in the middle of the 5Bq arm. It is proposed to designate the cv. Cappelli Ph1− mutation as ph1c.Key words: Triticum, map distortion, homoeologous pairing, chromosome pairing, chromosome rearrangement.

Spindle sensitivity to colchicine of the Ph1 mutant in common wheat

1984 ◽  
Vol 26 (2) ◽  
pp. 111-118 ◽  
Author(s):  
Carla Ceoloni ◽  
Lydia Avivi ◽  
Moshe Feldman
Keyword(s):  
Common Wheat ◽  
Root Tip ◽  
Control Line ◽  
Wild Type ◽  
Chromosomal Distribution ◽  
Chromosome 5B ◽  
Ph1 Locus ◽  
Ph1 Gene ◽  
Tip Cells ◽  
Different Doses

Mitotic spindle sensitivity to colchicine of a common wheat line carrying a mutation at the Ph1 locus which increases homoeologous pairing at meiosis, was studied in treated root-tip cells and compared with that of wild type (Ph1/Ph1) and plants deficient for chromosome 5B. Spindle sensitivity was determined by the percentage of fully affected cells of the overall metaphase cell population. The high-pairing mutant (ph1b/ph1b), which is assumed to be a deficiency for the Ph1 locus on the long arm of chromosome 5B, was found to be significantly more sensitive to colchicine than the corresponding control line, i.e., plants carrying the wild-type allele, Ph1. The sensitivity of the mutant was similar to that of plants deficient for chromosome 5B. It thus becomes highly probable that spindle sensitivity to colchicine, previously found in plants carrying different doses of chromosomal arm 5BL, is indeed determined by the Ph1 gene. This gene presumably exerts its effect on the spindle via modification of some microtubular components. Thus, microtubules are suggested to be a possible target structure for this gene, which is known to affect chromosomal distribution and degree of homologous and homoeologous association in somatic and premeiotic cells, as well as the pattern of meiotic pairing.Key words: spindle, Triticum, microtubules, colchicine.

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.

CYTOGENETICS OF A BARLEY × RYE HYBRID

1979 ◽  
Vol 21 (4) ◽  
pp. 543-548 ◽  
Author(s):  
George Fedak
Keyword(s):  
Hordeum Vulgare ◽  
Chromosome Number ◽  
Chromosome Pairing ◽  
Secale Cereale ◽  
Chiasma Frequency ◽  
Somatic Chromosome ◽  
Pollen Parent ◽  
Somatic Chromosome Number ◽  
Hordeum Vulgare L ◽  
Secale Cereale L

A viable hybrid with a somatic chromosome number of 14 was obtained by crossing Hordeum vulgare L. with Secale cereale L. Chromosome pairing in the hybrid was very low with an average chiasma frequency of 0.22. Phenotypically the hybrid resembled rye, the pollen parent, but the nucleolar characteristics were similar to barley.

scholarly journals A DNA fragment mapped within the submicroscopic deletion of Ph1, a chromosome pairing regulator gene in polyploid wheat.

Genetics ◽  
1991 ◽  
Vol 129 (1) ◽  
pp. 257-259 ◽  
Author(s):  
K S Gill ◽  
B S Gill
Keyword(s):  
Direct Evidence ◽  
Genetic Material ◽  
Homologous Pairing ◽  
Chromosome Walking ◽  
Chromosome Fragment ◽  
Chromosome 5B ◽  
Ph1 Gene ◽  
Dna Fragment ◽  
Homoeologous Chromosomes ◽  
Submicroscopic Deletion

Abstract Bread wheat is an allohexaploid consisting of three genetically related (homoeologous) genomes. The homoeologous chromosomes are capable of pairing but strict homologous pairing is observed at metaphase 1. The diploid-like pairing is regulated predominantly by Ph1, a gene mapped on long arm of chromosome 5B. We report direct evidence that a mutant of the gene (ph1b) arose from a submicroscopic deletion. A probe (XksuS1-5) detects the same missing fragment in two independent mutants ph1b and ph1c and a higher intensity fragment in a duplication of the Ph1 gene. It is likely that XksuS1-5 lies adjacent to Ph1 on the same chromosome fragment that is deleted in ph1b and ph1c. XksuS1-5 can be used to tag Ph1 gene to facilitate incorporation of genetic material from homoeologous genomes of the Triticeae. It may also be a useful marker in cloning Ph1 gene by chromosome walking.

Synthesis and cytological characterization of trigeneric hybrids of durum wheat with and without Ph1

Genome ◽  
2004 ◽  
Vol 47 (6) ◽  
pp. 1173-1181 ◽  
Author(s):  
Prem P Jauhar ◽  
M Doğramaci ◽  
T S Peterson
Keyword(s):  
In Situ Hybridization ◽  
Chromosome Pairing ◽  
Genetic Recombination ◽  
Genomic In Situ Hybridization ◽  
Homoeologous Pairing ◽  
Alien Gene Transfer ◽  
Chromosome 5B ◽  
Alien Gene ◽  
Trigeneric Hybrids

Wild grasses in the tribe Triticeae, some in the primary or secondary gene pool of wheat, are excellent reservoirs of genes for superior agronomic traits, including resistance to various diseases. Thus, the diploid wheatgrasses Thinopyrum bessarabicum (Savul. and Rayss) Á. Löve (2n = 2x = 14; JJ genome) and Lophopyrum elongatum (Host) Á. Löve (2n = 2x = 14; EE genome) are important sources of genes for disease resistance, e.g., Fusarium head blight resistance that may be transferred to wheat. By crossing fertile amphidiploids (2n = 4x = 28; JJEE) developed from F1 hybrids of the 2 diploid species with appropriate genetic stocks of durum wheat, we synthesized trigeneric hybrids (2n = 4x = 28; ABJE) incorporating both the J and E genomes of the grass species with the durum genomes A and B. Trigeneric hybrids with and without the homoeologous-pairing suppressor gene, Ph1, were produced. In the absence of Ph1, the chances of genetic recombination between chromosomes of the 2 useful grass genomes (JE) and those of the durum genomes (AB) would be enhanced. Meiotic chromosome pairing was studied using both conventional staining and fluorescent genomic in situ hybridization (fl-GISH). As expected, the Ph1-intergeneric hybrids showed low chromosome pairing (23.86% of the complement), whereas the trigenerics with ph1b (49.49%) and those with their chromosome 5B replaced by 5D (49.09%) showed much higher pairing. The absence of Ph1 allowed pairing and, hence, genetic recombination between homoeologous chromosomes. Fl-GISH analysis afforded an excellent tool for studying the specificity of chromosome pairing: wheat with grass, wheat with wheat, or grass with grass. In the trigeneric hybrids that lacked chromosome 5B, and hence lacked the Ph1 gene, the wheat–grass pairing was elevated, i.e., 2.6 chiasmata per cell, a welcome feature from the breeding standpoint. Using Langdon 5D(5B) disomic substitution for making trigeneric hybrids should promote homoeologous pairing between durum and grass chromosomes and hence accelerate alien gene transfer into the durum genomes.Key words: alien gene transfer, chiasma (xma) frequency, chromosome pairing, fluorescent genomic in situ hybridization (fl-GISH), homoeologous-pairing regulator, specificity of chromosome pairing, wheatgrass.

PrBn, a Major Gene Controlling Homeologous Pairing in Oilseed Rape (Brassica napus) Haploids

Genetics ◽  
2003 ◽  
Vol 164 (2) ◽  
pp. 645-653 ◽  
Author(s):  
Eric Jenczewski ◽  
Frédérique Eber ◽  
Agnès Grimaud ◽  
Sylvie Huet ◽  
Marie Odile Lucas ◽  
...  
Keyword(s):  
Brassica Napus ◽  
Oilseed Rape ◽  
Chromosome Pairing ◽  
Major Gene ◽  
Major Effect ◽  
F1 Hybrids ◽  
Precise Control ◽  
Ph1 Locus ◽  
Likelihood Approach ◽  
Likelihood Ratio Statistics

Abstract Precise control of chromosome pairing is vital for conferring meiotic, and hence reproductive, stability in sexually reproducing polyploids. Apart from the Ph1 locus of wheat that suppresses homeologous pairing, little is known about the activity of genes that contribute to the cytological diploidization of allopolyploids. In oilseed rape (Brassica napus) haploids, the amount of chromosome pairing at metaphase I (MI) of meiosis varies depending on the varieties the haploids originate from. In this study, we combined a segregation analysis with a maximum-likelihood approach to demonstrate that this variation is genetically based and controlled mainly by a gene with a major effect. A total of 244 haploids were produced from F1 hybrids between a high- and a low-pairing variety (at the haploid stage) and their meiotic behavior at MI was characterized. Likelihood-ratio statistics were used to demonstrate that the distribution of the number of univalents among these haploids was consistent with the segregation of a diallelic major gene, presumably in a background of polygenic variation. Our observations suggest that this gene, named PrBn, is different from Ph1 and could thus provide complementary information on the meiotic stabilization of chromosome pairing in allopolyploid species.

CHROMOSOME PAIRING IN POA ANNUA L.

1973 ◽  
Vol 15 (3) ◽  
pp. 549-551 ◽  
Author(s):  
W. M. Ellis ◽  
B. T. O. Lee ◽  
D. M. Calder
Keyword(s):  
Chromosome Pairing ◽  
Breeding System ◽  
Tetraploid Plant ◽  
Poa Annua ◽  
Diploid Population ◽  
Bivalent Formation

Cytological studies carried out on six tetraploid and one diploid population and a synthesized tetraploid plant have shown regular bivalent formation at meiosis. This regularity appears to be genetically controlled in this species. Plants from all the populations behave as diploids. The implications of this regular disomic chromosome pairing on recombination, variation and the breeding system of P. annua are considered.

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