scholarly journals LATENT NONSTRUCTURAL DIFFERENTIATION AMONG HOMOLOGOUS CHROMOSOMES AT THE DIPLOID LEVEL: CHROMOSOME 6Be OF AEGILOPS LONGISSIMA

Genetics ◽  
1986 ◽  
Vol 114 (2) ◽  
pp. 579-592
Author(s):  
Rama S Kota ◽  
Patrick E McGuire ◽  
Jan Dvořák
Keyword(s):  
Chromosome Pairing ◽  
Chinese Spring ◽  
Constitutive Heterochromatin ◽  
Diploid Species ◽  
Triticum Aestivum L ◽  
Homologous Chromosomes ◽  
B Genome ◽  
Aegilops Longissima ◽  
Chinese Spring Wheat ◽  
Diploid Level

ABSTRACT Previous work has shown that chromosome pairing at metaphase I (MI) of wheat homologous chromosomes from different inbred lines (heterohomologous chromosomes) is reduced relative to that between homologous chromosomes within an inbred line (euhomologous chromosomes). In order to determine if a potential for this phenomenon exists in diploid species closely related to the wheat B genome, MI chromosome pairing was investigated between euhomologous and heterohomologous 6Be (=6Se) chromosomes, each from a different population of Aegilops longissima Schweinf. et Muschl. (2n = 2x = 14) substituted for chromosome 6B of Chinese Spring wheat (Triticum aestivum L., 2n = 6x = 42). Euhomologous and heterohomologous monotelodisomics, i.e., plants with one complete chromosome 6Be and a telosome of either 6Bep or 6Beq, were constructed in the isogenic background of Chinese Spring. Pairing at MI of the Ae. longissima chromosomes was reduced in heterohomologous monotelodisomics compared to that in the corresponding euhomologous monotelodisomics. The remaining 20 pairs of Chinese Spring chromosomes paired equally well in the euhomologous and heterohomologous monotelodisomics. Thus, the cause of the reduced pairing must reside specifically in the Ae. longissima heterohomologues. In the hybrids between the Ae. longissima lines that contributed the substituted chromosomes, pairing between the heterohomologous chromosomes was normal and did not differ from that of the euhomologous chromosomes. These data provide evidence that a potential for reduced pairing between the heterohomologues is present in the diploid species, but is expressed only in the polyploid wheat genetic background. The reduction in heterohomologous chromosome pairing was greater in the p arm than in the q arm, exactly as in chromosome 6B of wheat. It is concluded that the reduced pairing between Ae. longissima heterohomologues has little to do with constitutive heterochromatin. The value of chromosome pairing as an unequivocal means of determining the origin of genomes in polyploid plants is questioned.

Meiotic pairing in wheat–rye addition and substitution lines

1984 ◽  
Vol 26 (1) ◽  
pp. 25-33 ◽  
Author(s):  
J. Orellana ◽  
M. C. Cermeño ◽  
J. R. Lacadena
Keyword(s):  
Chromosome Pairing ◽  
Chinese Spring ◽  
Constitutive Heterochromatin ◽  
Banding Technique ◽  
Addition Line ◽  
Meiotic Pairing ◽  
Addition Lines ◽  
Substitution Lines ◽  
Homologous Chromosomes ◽  
Complex Process

Chromosome pairing was examined in wheat–rye addition and substitution lines using the C-banding technique. It was found that both rye and wheat chromosomes affect each other's homologous pairing. The strongest diminution of wheat pairing (measured as bound arms per cell) was produced by chromosome 5R of rye (7.5 and 7.2% in 'Chinese Spring' – 'Imperial' and 'Holdfast' – 'King II' addition lines, respectively). The weakest diminution of wheat pairing was produced by chromosome 3R in the 'Chinese Spring' – 'Imperial' addition line (1.1%). The diminution of rye chromosome pairing produced by wheat chromosomes ranges from 6.9 to 48.4% ('Chinese Spring' – 'Imperial' and 'Holdfast' – 'King II' addition lines, respectively). When put into a wheat background, the rye chromosomes suffer a worse fate than the wheat chromosomes. For example, chromosome 6R reduces the wheat complement pairing in the 'Holdfast' – 'King II' addition line by 3.8% but its own pairing is reduced by 41.4%. The decrease in pairing of both wheat and rye homologous chromosomes in addition and substitution lines is a complex process in which factors such as genes controlling meiotic pairing, constitutive heterochromatin, and cryptic wheat–rye interactions can play important roles.

Mapping of a chromosome pairing gene and 5S rRNA genes in Triticum aestivum L. by a spontaneous deletion in chromosome arm 5Bp

1986 ◽  
Vol 28 (2) ◽  
pp. 266-271 ◽  
Author(s):  
Rama S. Kota ◽  
Jan Dvořák
Keyword(s):  
Triticum Aestivum ◽  
Chromosome Pairing ◽  
Chinese Spring ◽  
Triticum Aestivum L ◽  
5S Rrna ◽  
Rrna Genes ◽  
C Banding ◽  
Aegilops Longissima ◽  
Chromosome 5B ◽  
5S Rrna Genes

A deletion in the p arm of chromosome 5B of Triticum aestivum L. cv. Chinese Spring was identified by C-banding during the production of disomic substitutions of 6B of Aegilops longissima Schweinf. et Muschl. for chromosome 5B of cv. Chinese Spring. The deletion was terminal with a breakpoint just proximal to the interstitial C-band. The degree of metaphase I chromosome pairing in plants homozygous for the deletion indicated that the chromosome pairing promoting gene known to be in the p arm of chromosome 5B is located in the deleted portion of that arm. Additionally, all of the 5S ribosomal RNA genes known to exist on arm 5Bp were mapped to this deleted portion.Key words: C-banding, 5S rRNA genes, Triticum, Aegilops chromosome aberration.

Genomic Instability in Wheat Induced by Chromosome 6b(s) of Triticum Speltoides.

Genetics ◽  
1988 ◽  
Vol 120 (4) ◽  
pp. 1085-1094
Author(s):  
R S Kota ◽  
J Dvorak
Keyword(s):  
Chinese Spring ◽  
Wheat Chromosome ◽  
Triticum Aestivum L ◽  
Chromosome Rearrangements ◽  
D Genome ◽  
Dicentric Chromosomes ◽  
B Genome ◽  
Ring Chromosomes ◽  
Chinese Spring Wheat ◽  
A Genome

Abstract A massive restructuring of chromosomes was observed during the production of a substitution of chromosome 6B(s) from Triticum speltoides (Tausch) Gren. ex Richter for chromosome 6B of Chinese Spring wheat (Triticum aestivum L.). Deletions, translocations, ring chromosomes, dicentric chromosomes and a paracentric inversion were observed. Chromosome rearrangements occurred in both euchromatic and heterochromatic regions. Chromosome rearrangements were not observed either in the amphiploid between Chinese Spring and T. speltoides or in Chinese Spring. No chromosome rearrangements were observed in the backcross derivatives; however, after self-pollination of a monosomic substitution (2n = 41) of chromosome 6B(s) for wheat chromosome 6B, 49 of the 138 plants carried chromosome aberrations. Chromosome rearrangements were observed in both wheat and T. speltoides chromosomes. The frequency of chromosome rearrangements was high among the B-genome chromosomes, moderate among the A-genome chromosomes, and low among the D-genome chromosomes. In the B genome, the rearrangements were nonrandom, occurring most frequently in chromosomes 1B and 5B. Chromosome rearrangements were also frequent for the 6B(s) chromosome of T. speltoides. An intriguing aspect of these observations is that they indicate that wheat genomes can be subject to uneven rates of structural chromosome differentiation in spite of being in the same nucleus.

CHROMOSOME DIFFERENTIATION IN POLYPLOID SPECIES OF ELYTRIGIA, WITH SPECIAL REFERENCE TO THE EVOLUTION OF DIPLOID-LIKE CHROMOSOME PAIRING IN POLYPLOID SPECIES

1981 ◽  
Vol 23 (2) ◽  
pp. 287-303 ◽  
Author(s):  
J. Dvořák
Keyword(s):  
Triticum Aestivum ◽  
Special Reference ◽  
Normal Level ◽  
Chromosome Pairing ◽  
Chinese Spring ◽  
Triticum Aestivum L ◽  
Polyploid Species ◽  
Chromosome Differentiation

Triticum aestivum L. em Thell ditelosomics 7AL and 7DS and T. aestivum-Elytrigia elongata (Host) Holub (2n = 2x = 14) ditelosomic additions were crossed with "E. elongata 4x" (2n = 4x = 28), E. caespitosa (C. Koch) Nevski (2n = 4x = 28), and E. intermedia (Host) Nevski (2n = 6x = 42). The effect of each Elytrigia genotype on homoeologous (heterogenetic) chromosome pairing was assessed by comparing the pairing frequencies of T. aestivum cv. Chinese Spring telosomes 7AL and 7DS in the hybrids with the pairing frequency of telosome 7AL in haploid Chinese Spring. The genotype of "E. elongata 4x" had no effect on heterogenetic pairing in the hybrids. Although some genotypes of E. caespitosa and E. intermedia promoted heterogenetic pairing in the hybrids, others had no effect. Telosome VS of E. elongata interacted in a complementary fashion with the genotype of "E. elongata 4x," but not with the genotypes of Chinese Spring and E. caespitosa, and it promoted heterogenetic pairing. In hybrids in which the wheat diploidizing genes were active at the normal level, the E. elongata telosomes paired with chromosomes of "E. elongata 4x" in 5.8% to 24.6% of the cells, with chromosomes of E. caespitosa in 0.0% to 1.0% of the cells, and with chromosomes of E. intermedia in 0.0% to 2.8% of the cells. A model of chromosome differentiation is discussed and special attention is devoted to the origin of diploid-like pairing in polyploid species.

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.

Chromosome location of genes controlling aluminum tolerance in wheat, rye, and triticale

1984 ◽  
Vol 26 (6) ◽  
pp. 701-705 ◽  
Author(s):  
A. Aniol ◽  
J. P. Gustafson
Keyword(s):  
Chinese Spring ◽  
Wheat Variety ◽  
Aluminum Tolerance ◽  
Triticum Aestivum L ◽  
Additive Effects ◽  
Chromosome Location ◽  
Irreversible Damage ◽  
Wheat Varieties ◽  
Chinese Spring Wheat ◽  
Secale Cereale L

'Chinese Spring' wheat nullisomic–tetrasomic and ditelosomic lines were used for the identification of Aluminum-tolerance genes in wheat (Triticum aestivum L. em Thell.). Rye additions and substitutions in different wheat varieties were used for the identification of aluminum-tolerance genes in rye (Secale cereale L.). The point where concentrations of aluminum caused irreversible damage to the root apical meristems on exposure for 24 h at 25 °C was the measure of aluminum tolerance. Genes for aluminum tolerance in the medium-tolerant wheat variety 'Chinese Spring' were found to be localized in chromosome arms 6AL, 7AS, 2DL, 3DL, 4DL, and 4BL, and on chromosome 7D. Major genes for tolerance in rye seem to be located on 3R and 6RS, with other genes on 4R. The expression of aluminum-tolerance genes located on rye chromosomes incorporated into sensitive wheat was often suppressed by the action of unknown genes in the wheat background.Key words: Triticum, Secale, aluminum tolerance, additive effects, polygenes.

GENETIC REGULATION OF HETEROGENETIC CHROMOSOME PAIRING IN POLYPLOID SPECIES OF THE GENUS TRITICUM sensu lato

1982 ◽  
Vol 24 (1) ◽  
pp. 57-82 ◽  
Author(s):  
Patrick E. McGuire ◽  
Jan Dvořák
Keyword(s):  
Triticum Aestivum ◽  
Chromosome Pairing ◽  
Chinese Spring ◽  
Genetic Regulation ◽  
Triticum Aestivum L ◽  
Polyploid Species ◽  
D Genome ◽  
Chromosome 5B ◽  
A Genome

Polyploid species of Triticum sensu lato were crossed with Triticum aestivum L. em. Thell. cv. Chinese Spring monotelodisomics or ditelosomics that were monosomic for chromosome 5B. Progeny from these crosses were either euploid, nullisomic for 5B, monotelosomic for a given Chinese Spring chromosome, or nullisomic for 5B and monotelosomic simultaneously. The Chinese Spring telosome in the hybrids permitted the evaluation of autosyndesis of chromosomes of the tested species. In addition, several Chinese Spring eu- and aneuhaploids were produced. Genotypes of T. cylindricum Ces., T. juvenale Thell., T. triunciale (L.) Raspail, T. ovatum (L.) Raspail, T. columnare (Zhuk.) Morris et Sears, T. triaristatum (Willd.) Godr. et Gren., and T. rectum (Zhuk.) comb. nov. were all shown to have suppressive effects on heterogenetic pairing in hybrids lacking 5B or 3AS, whereas T. kotschyi (Boiss.) Bowden had no effect. It was concluded that diploid-like meiosis in these species is due to genetic regulation. A number of these genotypes promoted heterogenetic pairing in the presence of 5B. A model is presented to explain this dichotomous behavior of the tested genotypes. Monotelosomic-3AL haploids had a greater amount of pairing than did euhaploid Chinese Spring, which substantiated the presence of a pairing suppressor(s) on the 3AS arm. Evidence is presented that shows that T. juvenale does not have a genome homologous with the D genome of T. aestivum.

Dilemma of genome relationship in the diploid species Thinopyrum bessarabicum and Thinopyrum elongatum (Triticeae: Poaceae)

Genome ◽  
1990 ◽  
Vol 33 (6) ◽  
pp. 944-946 ◽  
Author(s):  
Prem P. Jauhar
Keyword(s):  
Chromosome Pairing ◽  
Constitutive Heterochromatin ◽  
Diploid Species ◽  
Total Content ◽  
Ploidy Levels ◽  
5S Dna ◽  
Thinopyrum Bessarabicum ◽  
Thinopyrum Elongatum ◽  
Relationship Of ◽  
The Relationship

Evidence on the relationship of the J genome of diploid Thinopyrum bessarabicum and the E genome of diploid Thinopyrum elongatum (= Lophopyrum elongatum) is discussed. Low chromosome pairing between J and E at different ploidy levels, suppression of J–E pairing by the Ph1 pairing regulator that inhibits homoeologous pairing, complete sterility of the diploid hybrids (JE), karyotypic differentiation of the two genomes and differences in their biochemical organization as reflected in total content and distribution of constitutive heterochromatin, and marked differences in isozymes, 5S DNA, and rDNA indicate that J and E are distinct genomes. These genomes are homoeologous and not homologous. There is no justification for the merger of J and E genomes.Key words: chromosome pairing, Ph1 pairing regulator, C-banding, isozymes, 5S DNA, rDNA.

Chinese spring wheat (Triticum aestivum L.) chloroplast genome: Complete sequence and contig clones

2000 ◽  
Vol 18 (3) ◽  
pp. 243-253 ◽  
Author(s):  
Yasunari Ogihara ◽  
Kazuriho Isono ◽  
Toshio Kojima ◽  
Akira Endo ◽  
Mitsumasa Hanaoka ◽  
...  
Keyword(s):  
Triticum Aestivum ◽  
Chloroplast Genome ◽  
Spring Wheat ◽  
Chinese Spring ◽  
Triticum Aestivum L ◽  
Complete Sequence ◽  
Chinese Spring Wheat
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