THE ANALYSIS OF MEIOSIS IN HYBRIDS. I. ANEUPLOID HYBRIDS

1981 ◽  
Vol 23 (2) ◽  
pp. 209-219 ◽  
Author(s):  
G. Kimber ◽  
L. C. Alonso ◽  
P. J. Sallee
Keyword(s):  
Triticum Aestivum ◽  
Mathematical Models ◽  
Chromosome Pairing ◽  
Meiotic Chromosome ◽  
Triticum Aestivum L ◽  
Equal Frequency ◽  
Chromosome Behavior ◽  
Telocentric Chromosomes ◽  
Genomic Relationships ◽  
Meiotic Analyses

The use of telocentric chromosomes in the analysis of the genomic relationships of wheat Triticum aestivum L. em Thell. and its relatives is described and 20 examples are given. The connection between this method of analysis and other mathematical theories of chromosome pairing in hybrids is established. A demonstration of the validity of the assumption that all chromosome arms pair at an equal frequency in calculating expected meiotic analyses is presented. This establishes a practical basis for the development of further mathematical models for predicting meiotic chromosome behavior. Numerical values of the genomic relationships of wheat and its immediate relatives are given.

Cytogenetic studies of progenies from crosses between 'Centurk' wheat and its doubled haploids derived from anther culture

Genome ◽  
1989 ◽  
Vol 32 (4) ◽  
pp. 622-628 ◽  
Author(s):  
Sawsan S. Youssef ◽  
R. Morris ◽  
P. S. Baenziger ◽  
C. M. Papa
Keyword(s):  
Triticum Aestivum ◽  
Chromosome Pairing ◽  
Doubled Haploid ◽  
Structural Changes ◽  
Meiotic Chromosome ◽  
Doubled Haploids ◽  
Triticum Aestivum L ◽  
Root Tips ◽  
Doubled Haploid Lines ◽  
A Minor

Karyotype stability, which is essential when using wheat (Triticum aestivum L.) doubled haploids in a breeding program, was evaluated in 14 anther-derived doubled-haploid lines after at least three generations of selfing, by crossing them as females with the parent cultivar 'Centurk' and doing cytological studies on the progenies. There were no deviations from the hexaploid chromosome number (2n = 42) in root tips. Meiotic chromosome pairing was as stable as that in the control ('Centurk' × 'Centurk') in most progenies. Chromosomal structural changes and (or) behavioral deviations were detected at the metaphase I, anaphase I, telophase I, and quartet stages of meiosis in a minor proportion of the cells. The frequencies of multivalents, lagging bivalents and univalents, bridges, and micronuclei were higher in some progenies than in the control. Chromosomal fragments were infrequent. The ranges in percentages of normal cells were 72.4–90.0 at anaphase I, 76.4–92.6 at telophase I, and 82.6–93.2 at quartet stages in the doubled-haploid progenies, compared with 95–100, 92–100, and 94–96, respectively, in the control. On the basis of these results, the doubled-haploid lines should produce enough normal gametes to provide adequate seed supplies when they are used as parents in wheat cultivar and population improvement.Key words: Triticum aestivum, chromosome pairing, chromosome aberrations, gametoclonal variation.

Transmission of an alien telocentric addition chromosome in common wheat that confers blue seed color

Genome ◽  
1989 ◽  
Vol 32 (1) ◽  
pp. 30-34 ◽  
Author(s):  
E. D. P. Whelan
Keyword(s):  
Triticum Aestivum ◽  
Common Wheat ◽  
Triticum Aestivum L ◽  
Seed Color ◽  
Chromosome Behavior ◽  
Phenotypic Markers ◽  
Telocentric Chromosome ◽  
Cytogenetic Studies ◽  
Meiotic Analyses ◽  
Color Gene

Phenotypic markers of chromosomes are useful for determining chromosome behavior in cytogenetic studies. Transmission of an alien, telocentric addition from Agropyron tricophorum (Link) Richt. that confers purple aleurone pigment and blue seed color was evaluated in common wheat (Triticum aestivum L.). Twenty-five of 2570 seeds from bagged heads of eight ditelocentric-addition sister plants were almost white rather than blue. Seven of these 25 seeds and 4 of 336 blue seeds segregated 41.4%:58.6% blue:white. Meiotic analyses showed that all plants grown from these 11 seeds were spontaneously produced monotelocentric additions. Transmission of the alien telocentric chromosome through the egg and the pollen was estimated to be 19.5 and 14.3%, respectively, based on BC1F1 seed color. About 28% of F2 and F3 seeds were blue; of these 7.4% were ditelocentric additions. The frequency of blue seed in F2 progeny from spontaneous monotelocentric additions (41.4%) was significantly greater than that of monotelocentric additions from controlled crosses (28%). Penetrance of the blue seed color gene(s) associated with the alien telocentric chromosome was good. Misclassification of seed color for 1595 BC1F1 seeds was less than 3% based on BC1F2 progeny.Key words: Agropyron tricophorum.

METAPHASE I PAIRING FREQUENCIES OF INDIVIDUAL AGROPYRON ELONGATUM CHROMOSOME ARMS WITH TRITICUM CHROMOSOMES

1979 ◽  
Vol 21 (2) ◽  
pp. 243-254 ◽  
Author(s):  
J. Dvořák
Keyword(s):  
Triticum Aestivum ◽  
Chromosome Pairing ◽  
Chromosome Complement ◽  
Triticum Aestivum L ◽  
Diploid Hybrid ◽  
Agropyron Elongatum ◽  
D Genome ◽  
Telocentric Chromosomes ◽  
Metaphase I

Ten telocentric chromosomes of diploid Agropyron elongatum (Host.) P.B. (2n = 14) were added to the chromosome complement of Triticum aestivum L. emend. Thell. The ditelosomic additions were crossed with Triticum speltoides (Tausch) Gren. ex Richter, and in the tetraploid hybrids the pairing frequencies of the telosomes were determined, expressed as percent of PMC's in which a telosome paired at metaphase I. All Agropyron telosomes paired with Triticum chromosomes. The pairing frequencies ranged from 4.4% to 41.2% of the PMC's, it is concluded that none of the ten Agropyron chromosome arms has a homologous partner among the four Triticum genomes involved. The pairing frequencies did not correlate with the lengths of the telosomes. Pairing of the Agropyron telosomes in these tetraploid hybrids approximated the chromosome pairing that occurred in a diploid hybrid T. tauschii (Coss.) Schmal. (the donor of the D genome of T. aestivum) × A. elongatum.

Intergeneric hybrids of Hordeum vulgare with Agropyron caninum and A. dasystachyum

1985 ◽  
Vol 27 (4) ◽  
pp. 387-392 ◽  
Author(s):  
George Fedak
Keyword(s):  
Hordeum Vulgare ◽  
Chromosome Pairing ◽  
Meiotic Chromosome ◽  
Intergeneric Hybrids ◽  
Spindle Fibre ◽  
Chromosome Behavior ◽  
Paternal Parent ◽  
Agropyron Caninum

Hybrids were obtained by pollinating Hordeum vulgare cv. Betzes with Agropyron caninum (4x) and A. dasystachyum (4x) at frequencies of 1.4 and 6.1% of pollinated florets, respectively. The hybrids were sterile and phenotypically resembled the paternal parent, except for floret structure which was intermediate between the parental types. Chromosome pairing at meiosis was very low and thus provided no indication of homoeology between parental genomes. Abnormal meiotic chromosome behavior in meiocytes that occurred in sectors on the 'Betzes' × A. dasystachyum hybrid was attributed to abnormal spindle fibre function.Key words: intergeneric hybrids, Hordeum vulgare, Agropyron caninum, Agropyron dasystachyum.

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.

Cytological and molecular characterization of a Triticum aestivum × Lophopyrum ponticum backcross derivative resistant to barley yellow dwarf

Genome ◽  
1994 ◽  
Vol 37 (5) ◽  
pp. 876-881 ◽  
Author(s):  
Gan-Yuan Zhong ◽  
Patrick E. Mcguire ◽  
Calvin O. Qualset ◽  
Jan Dvořák
Keyword(s):  
Triticum Aestivum ◽  
Chromosome Pairing ◽  
Barley Yellow Dwarf Virus ◽  
Virus Disease ◽  
Meiotic Chromosome ◽  
Yellow Dwarf ◽  
Homoeologous Chromosome ◽  
Barley Yellow Dwarf ◽  
Homoeologous Chromosome Pairing ◽  
Lophopyrum Ponticum

Barley yellow dwarf is the most damaging virus-caused disease in bread wheat (Triticum aestivum L.). A resistant line, SW335.1.2-13-11-1-5 (2n = 47), derived from a cross of T. aestivum × Lophopyrum ponticum was characterized by meiotic chromosome pairing, by in situ DNA hybridization and by expression of molecular markers to determine its chromosome constitution. All progeny of this line had three pairs of L. ponticum chromosomes from homoeologous chromosome groups 3, 5, and 6 and the 2n = 47 progeny had an additional L. ponticum monosome. The pairs from groups 3 and 6 were in the added state, while the group 5 pair was substituted for wheat chromosome 5D. Several wheat–wheat translocations with respect to the parental wheat genotype occurred in this line, presumably owing to the promotion of homoeologous chromosome pairing by L. ponticum chromosomes. It was hypothesized that homoeologous recombination results in homoeologous duplication–deletions in wheat chromosomes. An aberrant 3:1 disjunction creates the potential at each meiosis for replacement of these wheat chromosomes by homoeologous L. ponticum chromosomes. Wheat chromosomes 3A and 6A appeared to be in intermediate stages of this substitution process.Key words: wheat, wheatgrass, Lophopyrum, barley yellow dwarf virus, disease resistance, homoeologous chromosome recombination, homoeologous pairing, alien chromosome substitution.

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.

Meiotic abnormalities in primary regenerants from callus culture of immature embryos of 'Norstar' winter wheat

Genome ◽  
1990 ◽  
Vol 33 (2) ◽  
pp. 260-266 ◽  
Author(s):  
Ernest D. P. Whelan
Keyword(s):  
Triticum Aestivum ◽  
Tissue Culture ◽  
Winter Wheat ◽  
Structural Changes ◽  
Chromosome Structure ◽  
Triticum Aestivum L ◽  
Immature Embryos ◽  
Meiotic Abnormalities ◽  
Chromosomal Changes ◽  
Meiotic Analyses

Tissue culture can induce changes in chromosome structure and number in common wheat (Triticum aestivum L.). The type and frequency of such changes were evaluated in primary regenerants extracted from calli of four immature embryos of 'Norstar' winter wheat cultured for various durations. Meiotic analyses of samples from 18 or 19 primary regenerants from a single embryo cultured for 6, 10, or 14 weeks detected chromosomal changes in 17–20% of the samples. Analyses of 20 duplicate samples from these plants indicated that 7 (35%) plants were chimeras. Similar analyses for nine duplicate samples from plants extracted from an embryo cultured for 18 weeks failed to detect any chimeras, but meiotic abnormalities were much more frequent, with about one-half of the 46 plants sampled showing chromosomal structural changes; translocations were the most common abnormality. Plants regenerated from this embryo also were characterized by an abnormal chromosome, believed to contain a deletion, that was not considered to have been induced by tissue culture.Key words: tissue culture, meiotic abnormalities, Triticum aestivum, aneuploidy, translocations, chimeras.

AN ANALYTICAL STUDY OF CHROMOSOME BEHAVIOR IN A WHEAT HAPLOID

1955 ◽  
Vol 33 (1) ◽  
pp. 11-30 ◽  
Author(s):  
Clayton Person
Keyword(s):  
Triticum Aestivum ◽  
Inverse Relationship ◽  
Analytical Study ◽  
Triticum Aestivum L ◽  
Chromosome Movement ◽  
Chromosome Behavior ◽  
Polar Groups ◽  
End To End ◽  
Made In

Bivalents, univalents, end-to-end and side-by-side associations, also chromosome distributions to the poles were associatively recorded for each of approximately 2000 meta-anaphase cells of a haploid Triticum aestivum L. It was demonstrated that the distribution of the univalents to the polar groups was not random. An inverse relationship between side-by-side association and bivalent frequencies was also demonstrated, and this formed the first in a series of analytical steps which led to a description of chromosome movement in the haploid. The validity of certain assumptions concerning chromosome behavior was tested using the χ2 method; for others, confirmatory observations were made in monosomic cells.

Sign in / Sign up

Export Citation Format

Share Document