Chromosome pairing in female and male diploid and polyploid anurans (Amphibia) from South America

1983 ◽  
Vol 25 (5) ◽  
pp. 487-494
Author(s):  
I. M. Rahn ◽  
A. Martinez
Keyword(s):  
South America ◽  
Genetic Control ◽  
Chromosome Pairing ◽  
Diploid Males ◽  
Terminal Chiasmata

Chromosome pairing in females and males of diploid (2n = 22) and tetraploid (2n = 44) Odontophrynus americanus and diploid Ceratophrys cranwelli (2n = 26) and tetraploid C. ornata (2n = 104) showed that diploid females formed more chiasmata per paired arm than diploid males and polyploids of both sexes. There was a reduction in the level of recombination in female polyploids by forming multivalents with terminal chiasmata. The reduction reflected a change in the genetic control of pairing in females after polyploidization.

THE MEIOTIC BEHAVIOR OF ANEUPOLYHAPLOIDS OF THE CULTIVATED OAT AVENA SATIVA (2n = 6x = 42)

1977 ◽  
Vol 19 (4) ◽  
pp. 651-656 ◽  
Author(s):  
J. M. Leggett
Keyword(s):  
Genetic Control ◽  
Chromosome Pairing ◽  
Avena Sativa ◽  
Meiotic Behavior ◽  
Homoeologous Chromosomes

Chromosome pairing and the frequency of secondary associations in two aneupolyhaploid plants of A. sativa are described. There was little evidence of pairing between homoeologous chromosomes in either plant. The results are discussed in relation to the genetic control of bivalent pairing in A. sativa and the possible divergence between the constituent genomes.

Genetic control of meiosis in rice, Oryza sativa L. IV. Cytogenetical analyses of asynaptic mutants

1984 ◽  
Vol 26 (3) ◽  
pp. 264-271 ◽  
Author(s):  
Kunio Kitada ◽  
Takeshi Omura
Keyword(s):  
Oryza Sativa ◽  
Genetic Control ◽  
Chromosome Pairing ◽  
Chiasma Frequency ◽  
Oryza Sativa L ◽  
Recessive Gene ◽  
The Other ◽  
Normal Plant ◽  
Meiotic Stage ◽  
The Mean

One complete asynaptic mutant, MM-19, and two partial ones, MM-4 and MM-16, of Oryza sativa L. induced by N-methyl-N-nitrosourea (MNU) were cytogenetically investigated. No chromosome pairing occurred from zygotene to pachytene and 24 univalents appeared at diakinesis and metaphase 1 in MM-19. On the other hand, a partial lack of chromosome pairing was observed from zygotene to pachytene and various numbers of univalents occurred at metaphase I in MM-4 and MM-16. The mean chiasma frequency per bivalent as well as per cell decreased to different extents in MM-4 and MM-16, and the correlation between both the amount of chromosome pairing from zygotene to pachytene and the chiasma frequency per cell at diakinesis was recognized. Judging from the development of anthers in each meiotic stage, the duration of the stage forming the synizetic knot, at which chromosome pairing took place, was longer in MM-4 and MM-16 than in the normal plant, and was in MM-19 almost as long as in the normal plant. The results of gene analyses indicate that each of the three asynaptic mutants is controlled by a recessive gene and that, at least for MM-4 and MM-16, these genes are located at different loci.Key words: asynaptic, rice, Oryza, chiasma frequency, synizesis.

GENOME RELATIONSHIPS IN BROMUS ERECTUS, B. PUMPELLIANUS SSP. DICKSONII AND B. PUMPELLIANUS

1975 ◽  
Vol 17 (3) ◽  
pp. 391-394
Author(s):  
K. C. Armstrong
Keyword(s):  
Genetic Control ◽  
Chromosome Pairing ◽  
Low Frequency ◽  
Homoeologous Chromosome ◽  
Homoeologous Chromosome Pairing ◽  
Bivalent Formation ◽  
Bromus Erectus

Chromosome pairing was studied in hexaploid (2n = 42) hybrids of B. erectus (2n = 28) × B. pumpellianus (2n = 56) and B. pumpellianus ssp. dicksonii (2n = 28) × B. pumpellianus. Chromosome pairing in the B. erectus × B. pumpellianus hybrid was complete with predominantly bivalent formation and a low frequency of quadrivalents. The pairing results support the contention that B. pumpellianus is an autoalloploid with an AAAABBBB genome formula. The B. pumpellianus ssp. dicksonii × B. pumpellianus hybrid has an AAABBB genome formula. The presence of quadrivalents, hexavalents and cells containing a total number of bivalents or bivalents plus trivalents in excess of 14 indicated pairing between the A and B genomes. However, a high univalent frequency showed that the A and B genomes were homoeologous rather than homologous. Evidence for genetic control of homoeologous chromosome pairing and homoeologous differentiation between the genomes of the species is discussed.

The Genetic Control of Chromosome Pairing in Wheat

1990 ◽  
Vol 17 (3) ◽  
pp. 239 ◽  
Author(s):  
LH Ji ◽  
P Langridge
Keyword(s):  
Molecular Biology ◽  
Genetic Control ◽  
Mechanism Of Action ◽  
Chromosome Pairing ◽  
Genetic Information ◽  
Chromosome Pair ◽  
Homologous Chromosomes ◽  
Chromosome 5B ◽  
Cytogenetic Studies ◽  
Homoeologous Chromosomes

Bread wheat is an allohexaploid with three pairs of homoeologous chromosomes. This means that each chromosome pair is present in three related but not truly homologous chromosomes. In order to maintain the integrity of the three chromosome sets, pairing must be very tightly controlled at meiosis to allow homologous but not homoeologous chromosomes to pair and recombine. Several genes (termed Ph genes) are known to be involved in controlling chromosome pairing in wheat, but the strongest effect has been associated with a gene on the long arm of chromosome 5B, Phl. The manipulation of this gene can be used to induce recombination between chromosomes that will not normally pair at meiosis. This has application in the introduction of new genetic information into wheat. Elucidation of the mechanism of action of the Ph genes has centred around genetic and cytogenetic studies with little attempt to investigate the molecular biology or biochemistry of these genes. Isolation of genes in meiosis in yeast and genes associated with the aerly stages of meiosis in lily have provided a potential entry point into the identification of the analogous genes in wheat.

Genetic control of meiotic chromosome pairing in tetraploid Agropyron elongatum. I. Pattern of pairing in natural and induced tetraploids and in F1 triploid hybrids

1986 ◽  
Vol 28 (5) ◽  
pp. 783-788 ◽  
Author(s):  
A. Charpentier ◽  
M. Feldman ◽  
Y. Cauderon
Keyword(s):  
Control System ◽  
Genetic Control ◽  
Chromosome Pairing ◽  
Meiotic Chromosome ◽  
Agropyron Elongatum ◽  
Homologous Group ◽  
Meiotic Chromosome Pairing ◽  
Random Pairing ◽  
Expected Values ◽  
High Level

Meiotic chromosome pairing was studied in natural and induced tetraploid Agropyron elongatum, as well as in triploid hybrids between natural tetraploid and diploid cytotypes. The natural tetraploids showed a highly regular, diploid-like pairing, while the induced ones showed an average of two to three multivalents per cell. A high level of pairing was exhibited by the triploid hybrids, 4.15 bivalents and 2.82 trivalents per cell, supporting the assumption that the natural tetraploid is of an autoploid origin. Frequencies of meiotic configurations of the induced tetraploid and of the F1 triploid hybrids deviated significantly from the expected values based on a model assuming random pairing within one homologous group in autoploids: the observed data were characterized by fewer multivalents than expected, indicating a tendency towards bivalentization. This tendency is fully realized in the natural tetraploid. The presence of a pairing-control system in these autoploids, most probably a genetic one, that determines bivalent rather than multivalent pairing is suggested.Key words: Agropyron, pairing, bivalentization, tetraploid, multivalents.

INCOMPLETE CONCURRENCE OF EVIDENCE FROM PROTEIN ELECTROPHORESIS AND GENOME ANALYSIS REGARDING THE ORIGIN OF AEGILOPS OVATA

1975 ◽  
Vol 17 (1) ◽  
pp. 1-8 ◽  
Author(s):  
J. Giles Waines ◽  
B. Lennart Johnson
Keyword(s):  
Genetic Control ◽  
Chromosome Pairing ◽  
Genome Analysis ◽  
Diploid Species ◽  
Introgressive Hybridization ◽  
Seed Proteins ◽  
Protein Electrophoresis ◽  
Water Soluble ◽  
Genome Divergence

Electrophoresis of ethanol extracted, water soluble, seed proteins of many different biotypes of 3 diploid species of Aegilops and of the tetraploid A. ovata L. suggest that A. ovata may be descended from an allotetraploid of A. umbellulata Zhuk. and A. squarrosa L. This does not agree with the few published results of genome analysis, which suggest that A. umbellulata and A. comosa Sibth. &Smith are the ancestors of A. ovata. Hypotheses advanced to explain this incomplete concurrence of evidence from these two biosystematic methods include an insufficiency of samples, genome divergence, translocations followed by introgressive hybridization and genetic control of meitoic chromosome pairing.

Genetic Control of Chromosome Pairing in Hexaploid Oats

1972 ◽  
Vol 239 (94) ◽  
pp. 217-219 ◽  
Author(s):  
TIBOR RAJHATHY ◽  
HUGH THOMAS
Keyword(s):  
Genetic Control ◽  
Chromosome Pairing
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