CHROMOSOME RELATIONSHIPS AND MORPHOLOGICAL COMPARISONS BETWEEN THE DIPLOID OATS AVENA PROSTRATA, A. CANARIENSIS AND THE TETRAPLOID A. MAROCCANA

1980 ◽  
Vol 22 (2) ◽  
pp. 287-294 ◽  
Author(s):  
J. M. Leggett
Keyword(s):  
Chromosome Pairing ◽  
Cytological Evidence ◽  
Geographical Data ◽  
Tetraploid Hybrid ◽  
A Genome

The morphology and chromosome pairing of the triploid hybrids Avena canariensis Baum, Rajhathy et Sampson × A. maroccana Gdgr., A. prostrata Ladiz × A. maroccana, the diploid A. prostrata and the tetraploid derived between A. prostrata and A. canariensis and the tetraploid hybrid between this derived tetraploid and A. maroccana are described in relation to genomic affinities between these species. The cytological evidence is at variance with morphological and geographical data which initially indicated that A. canariensis was the donor of the A genome of the A. maroccana-A. murphyi group of tetraploids. The possible relationship between the species is briefly discussed.

Chromosome pairing in triploid and tetraploid hybrids in Elytrigia (Triticeae; Poaceae)

1984 ◽  
Vol 26 (5) ◽  
pp. 519-522 ◽  
Author(s):  
Patrick E. McGuire
Keyword(s):  
Chromosome Pairing ◽  
Genome Analysis ◽  
Triploid Hybrid ◽  
Pollen Mother Cells ◽  
Tetraploid Hybrid ◽  
A Genome ◽  
Mother Cells ◽  
Metaphase I

Mean chromosome pairing of 5.14I + 1.28II (rod) + 3.86II (ring) + 1.47III + 0.11IV (open) + 0.11V was observed in pollen mother cells at metaphase I in the triploid hybrid Elytrigia scirpea (K. Presl) Holub, 2n = 4x = 28 × E. bessarabica (Savul. et Rayss) Dubrovik, 2n = 4x = 14. Mean chromosome pairing of 3.71I + 2.29II (rod) + 1.82II (ring) + 2.64III + 0.29IV (open) was observed in the triploid hybrid E. curvifolia (Lange) Holub, 2n = 4x = 28 × E. bessarabica. Mean chromosome pairing of 3.00I + 0.93II (rod) + 1.57II (ring) + 1.36III + 1.79IV (open) + 1.I4IV (closed) + 0.79V was observed in the tetraploid hybrid E. junceiformis Löve et Löve, 2n = 4x = 28 × E. curvifolia. The first hybrid provides the first evidence by genome analysis that E. bessarabica possesses a genome (designated Eb) which is closely related to the genomes of E. scirpea (ES and ESC) and hence to the E genome of E. elongata (Host) Nevski, 2n = 2x = 14. The second and third hybrids provide the first evidence that the two genomes of E. curvifolia (designated EC and ECU) are related to the Eb genome of E. bessarabica and thus to the E genome of E. elongata.Key words: Elytrigia, homoeology, Triticum, phylogeny, triploid, tetraploid.

Nature of chromosome pairing in SH-genome octaploids involving Elymus canadensis and E. trachycaulus: a genome dose dependent bivalentizing mechanism

Genome ◽  
1990 ◽  
Vol 33 (5) ◽  
pp. 613-618 ◽  
Author(s):  
P. S. Kumar ◽  
P. D. Walton
Keyword(s):  
Chromosome Pairing ◽  
Chromosome Doubling ◽  
Tetraploid Hybrid ◽  
Polygenic Control ◽  
A Genome ◽  
Structural Differences ◽  
Bivalent Formation ◽  
Elymus Canadensis ◽  
Tetraploid Level ◽  
Dose Dependent

In spite of regular chromosome pairing, hybrids between Elymus canadensis (Linnaeus) and E. trachycaulus (Link) Gould ex Shinners at the tetraploid level are sterile owing to structural differences between the donor genomes. However, the hybrids between these species at the octaploid level (obtained through chromosome doubling of the tetraploid hybrid and also from a cross between the octaploids of E. canadensis and E. trachycaulus) exhibited a predominance of bivalents in meiosis in spite of the autotetraploid nature of their constituent S and H genomes. The colchicine-induced amphiploids showed varying degrees of fertility. Comparison of chromosome pairing in the hybrid octaploids with that in the parental octaploids and hexaploids revealed that random bivalent formation is promoted when the S and (or) H genomes are at the tetraploid level, but not when they are in the triploid state. A bivalentizing mechanism under polygenic control is suggested to explain the predominance of bivalents in the tetraploid S and H genomes.Key words: Elymus, S genome, H genome, octaploids, bivalents, bivalentization.

Genome elimination in diploid and triploid Rana esculenta males: cytological evidence from DNA flow cytometry

Genome ◽  
1990 ◽  
Vol 33 (5) ◽  
pp. 619-627 ◽  
Author(s):  
A. E. Vinogradov ◽  
L. J. Borkin ◽  
R. Günther ◽  
J. M. Rosanov
Keyword(s):  
Flow Cytometry ◽  
Genetic Material ◽  
Rana Esculenta ◽  
Mendelian Inheritance ◽  
Study Data ◽  
Dna Flow Cytometry ◽  
Cytological Evidence ◽  
Water Frog ◽  
A Genome ◽  
Rana Lessonae

Cytological aspects of hemiclonal (meroclonal) inheritance in diploid and triploid males of the hybridogenetic frog Rana esculenta (Rana ridibunda × Rana lessonae) have been studied by DNA flow cytometry. The fact that the R. ridibunda genome contains 16% more DNA than the R. lessonae genome provides the ability to discern cells containing genomes of any species from the water-frog complex under study. Data are presented showing that elimination of the R. ridibunda genome occurs in hybridogenetic males from certain populations. In triploid males, the cytogenetic mechanism of hemiclonal inheritance is simpler than in diploids: after the elimination of a genome (always the genome in the minority in the triploid set; "homogenizing elimination"), no compensatory duplication of the remaining genetic material is necessary, as it is in diploids. The process of elimination can be visualized in triploid males by using DNA flow cytometry to identify cells in the special phase of the spermatogonial cell cycle that we termed the E phase.Key words: Rana esculenta, genome elimination, non-Mendelian inheritance, spermatogenesis, DNA flow cytometry.

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.

A AND B GENOME HOMOEOLOGIES IN TETRAPLOID AND OCTOPLOID CYTOTYPES OF BROMUS INERMIS

1979 ◽  
Vol 21 (1) ◽  
pp. 65-71 ◽  
Author(s):  
K. C. Armstrong
Keyword(s):  
Chromosome Pairing ◽  
Convincing Evidence ◽  
Bromus Inermis ◽  
Open Pollination ◽  
Homoeologous Chromosome ◽  
Genome Chromosome ◽  
B Genome ◽  
Homoeologous Chromosome Pairing ◽  
A Genome ◽  
Structural Differences

Homoeology between the A and B genomes of allotetraploid (2n = 4x = 28) AiAiBiBi and autoallooctoploid (2n = 8x = 56) AIAIAIAIBIBIBIBI cytotypes of B. inermis Leyss. was studied in a tetraploid F1 hybrid (AeAeAiBi) from 4x B. erectus × 4x B. inermis and in a haplo-triploid (AIeAIeBI) which occurred spontaneously in the F2 from open-pollination among plants of the hexaploid F1 hybrid (AeAeAIAIBIBI) from 4x B. erectus × 8x B. inermis. Chromosome pairing at metaphase I in both the tetraploid (AeAeAiBi) and haplo-triploid (AIeAIeBI) indicated that for each A genome chromosome there was a corresponding B genome homoeologue. There was no convincing evidence of gross structural differences between the two homoeologous genomes. The frequency of trivalent formation in the haplo-triploid was approximately one-half that found in two pentaploids (2n = 5x = 35) AIeAIeAIBIBI. This indicates that the pairing affinity between the A and B genomes is one-half that between homologues as expressed by trivalent formation in triploids of the type AAB and AAA. Homoeologous chromosome pairing (A with B) may be controlled by a gene which is hemizygous ineffective.

Reinvestigation of the S genome in Triticum kotschyi

Genome ◽  
1990 ◽  
Vol 33 (4) ◽  
pp. 521-524 ◽  
Author(s):  
Yang Yen ◽  
Gordon Kimber
Keyword(s):  
Chromosome Pairing ◽  
Reciprocal Translocation ◽  
Triploid Hybrid ◽  
First Report ◽  
Tetraploid Hybrid ◽  
Donor Species

Hybrids of Triticum kotschyi with induced autotetraploids of Triticum longissimum, Triticum speltoides, and Triticum bicorne and diploid T. speltoides were obtained. This is the first report of successful hybridization between T. kotschyi and T. bicorne. Optimizing meiotic data showed that the tetraploid hybrid involving T. longissimum (4x) fit the 3:1 model best with an x-value of 1.000, while those involving T. speltoides (4x) and T. bicorne (4x) fit the 2:2 and 2:1:1 models best with an x-value of 0.744 and 0.989, respectively. The triploid hybrid of T. kotschyi × T. speltoides fit the 3:0 model best with an x-value of 0.500. A reciprocal translocation was observed between T. kotschyi and T. speltoides. It is suggested that T. longissimum is the possible donor species of the S genome to T. kotschyi and that this S genome has remained essentially unchanged since its incorporation. This and other evidence suggest that T. kotschyi likely originated from the hybridization of T. longissimum × T. umbellulatum.Key words: hybrid, meiosis, chromosome pairing, autotetraploid, phylogenesis.

Further hybrids involving the perennial autotetraploid oat Avena macrostachya

Genome ◽  
1992 ◽  
Vol 35 (2) ◽  
pp. 273-275 ◽  
Author(s):  
J. M. Leggett
Keyword(s):  
Chromosome Pairing ◽  
Triploid Hybrid ◽  
Genome Species ◽  
A Genome ◽  
C Genome

Chromosome pairing in the triploid hybrid Avena damascena × A. macrostachya is very similar to the chromosome pairing observed in previously reported triploid hybrids involving the A genome diploid taxa A. atlantica and A. prostrata, indicating that little more than residual homology remains between these A genome diploids and either of the genomes of A. macrostachya. The chromosome pairing in the hybrid between A. macrostachya and the C genome diploid A. ventricosa is similar to that observed in the previously reported hybrid A. eriantha × A. macrostachya. In both these hybrids, the frequency of trivalents is greater than that observed in hybrids involving the A genome species and A. macrostachya, which is indicative of closer homology of A. macrostachya to the C genome diploids than the A genome diploids.Key words: Avena, hybrids, interspecific chromosome pairing, phylogeny.

Cytogenetics of a synthesized allopentaploid (2n = 5x = 100) in the genus Glycine subgenus Glycine

Genome ◽  
1991 ◽  
Vol 34 (5) ◽  
pp. 751-756 ◽  
Author(s):  
R. J. Singh ◽  
T. Hymowitz
Keyword(s):  
Chromosome Pairing ◽  
Morphological Traits ◽  
Colchicine Treatment ◽  
Close Similarity ◽  
Breeding Behavior ◽  
A Genome ◽  
Origin Identification

The objectives of this study were to provide information on the origin, identification, meiosis, and breeding behavior of a synthesized allopentaploid (2n = 5x = 100) in the genus Glycine (Willd.) subgenus Glycine. The origin of the pentaploid plant was as follows: G. clandestina, 2n = 2x = 40, A1A1 × G. canescens, 2n = 2x = 40, AA (designated as H119), F1 (2n = 2x = 40, AA1) × G. tomentella (2n = 4x = 80, AxAxDD) → F1 (2n = 3x = 60, AAxD (assuming A-genome chromosomes from G. canescens were transmitted)) → 0.1% colchicine treatment → 2n = 6x = 120 (AAAxAxDD) × G. tomentella (2n = 4x = 80, AxAxDD) → BC1, 2n = 5x = 100 (AAxAxDD). Morphologically, the pentaploid plant very closely resembled the tetraploid G. tomentella, PI 441005. Compared with hexaploids, the pentaploid plant was less vigorous for several morphological traits. However, it was not possible to distinguish visually among 4x, 5x, and 6x plants. Intergenomic chromosome pairing was followed in hexaploid (A–A, Ax–Ax, D–D) and pentaploid (A, Ax–Ax, D–D) plants. Despite a close similarity between A and Ax genomes (A- and Ax-genome chromosomes pair normally in the absence of their homologues) meiotic stages were highly abnormal in the pentaploid, with univalents, laggards, and micronuclei, but the plant set normal pods and seeds. The pentaploid plant did not breed true, as chromosomes in the 14 examined plants of the progeny ranged from 2n = 86 to 97. Furthermore, progeny of a plant with 2n = 90 segregated for plants with 2n = 81–86. These results indicate that the preferential elimination of G. canescens (A genome) chromosomes is rapid and eventually AxAxDD genome chromosomes will prevail. Thus, pentaploids will stabilize at the tetraploid level.Key words: Glycine spp., allopolyploidy, chromosome pairing, genome.

The initiation of meiotic chromosome pairing: the cytological view

Genome ◽  
1990 ◽  
Vol 33 (6) ◽  
pp. 759-778 ◽  
Author(s):  
Josef Loidl
Keyword(s):  
Synaptonemal Complex ◽  
Chromosome Pairing ◽  
Meiotic Chromosome ◽  
Meiotic Pairing ◽  
Cytological Evidence ◽  
Homologous Chromosomes ◽  
Synaptonemal Complex Formation ◽  
Meiotic Synapsis ◽  
The One ◽  
First Contact

Opposing views are held with respect to the time when and the mechanisms whereby homologous chromosomes find each other for meiotic synapsis. On the one hand, some evidence has been presented for somatic homologous associations or some other kind of relationship between chromosomes in somatic cells as a preliminary to meiotic pairing. On the other hand, it is argued by many that homologous contacts are first established at meiotic prophase prior to, or in the course of, synaptonemal complex formation. The present paper reviews the controversial cytological evidence, hypotheses, and ideas on how the first contact between homologous chromosomes comes about.Key words: synapsis, meiosis, presynaptic alignment, homologous recognition, synaptonemal complex, chromosome pairing.

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