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.

scholarly journals Meiotic chromosome pairing in triploid and tetraploid Saccharomyces cerevisiae.

Genetics ◽  
1995 ◽  
Vol 139 (4) ◽  
pp. 1511-1520 ◽  
Author(s):  
J Loidl
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Complex Formation ◽  
Chromosome Segregation ◽  
Chromosome Pairing ◽  
Meiotic Chromosome ◽  
Low Frequency ◽  
Spore Viability ◽  
Homologous Chromosomes ◽  
Meiotic Chromosome Pairing ◽  
Synaptonemal Complex Formation

Abstract Meiotic chromosome pairing in isogenic triploid and tetraploid strains of yeast and the consequences of polyploidy on meiotic chromosome segregation are studied. Synaptonemal complex formation at pachytene was found to be different in the triploid and in the tetraploid. In the triploid, triple-synapsis, that is, the connection of three homologues at a given site, is common. It can even extend all the way along the chromosomes. In the tetraploid, homologous chromosomes mostly come in pairs of synapsed bivalents. Multiple synapsis, that is, synapsis of more than two homologues in one and the same region, was virtually absent in the tetraploid. About five quadrivalents per cell occurred due to the switching of pairing partners. From the frequency of pairing partner switches it can be deduced that in most chromosomes synapsis is initiated primarily at one end, occasionally at both ends and rarely at an additional intercalary position. In contrast to a considerably reduced spore viability (approximately 40%) in the triploid, spore viability is only mildly affected in the tetraploid. The good spore viability is presumably due to the low frequency of quadrivalents and to the highly regular 2:2 segregation of the few quadrivalents that do occur. Occasionally, however, quadrivalents appear to be subject to 3:1 nondisjunction that leads to spore death in the second generation.

Inferences from genetical evidence on the course of meiotic chromosome pairing in plants

1977 ◽  
Vol 277 (955) ◽  
pp. 313-326 ◽  
Keyword(s):  
Chromosome Pairing ◽  
Developmental Stages ◽  
Meiotic Chromosome ◽  
Critical Assessment ◽  
Gene Control ◽  
Meiotic Pairing ◽  
Homologous Chromosomes ◽  
Meiotic Chromosome Pairing ◽  
Combined Use ◽  
Or Gene

Meiotic chromosome pairing is a process that is amenable to genetic and experimental analysis. The combined use of these two approaches allows for the process to be dissected into several finite periods of time in which the developmental stages of pairing can be precisely located. Evidence is now available, in particular in plants, that shows that the pairing of homologous chromosomes, as observed at metaphase I, is affected by events occurring as early as the last premeiotic mitosis; and that the maintenance of this early determined state is subsequently maintained by constituents (presumably proteins) that are sensitive to either colchicine, temperature or gene control. A critical assessment of this evidence in wheat and a comparison of the process of pairing in wheat with the course of meiotic pairing in other plants and animals is presented.

Chromosome pairing in Oryza sativa L. × O. latifolia Desv. hybrids

1986 ◽  
Vol 28 (2) ◽  
pp. 278-281 ◽  
Author(s):  
E. M. Nowick
Keyword(s):  
Oryza Sativa ◽  
Chromosome Pairing ◽  
Embryo Culture ◽  
Oryza Sativa L ◽  
Meiotic Chromosome ◽  
Genetic System ◽  
Meiotic Chromosome Pairing

Meiotic chromosome pairing was examined in F1 hybrid regenerants from Oryza sativa (AA) × O. latifolia (CCDD) and O. glumaepatula (AcuAcu) × O. latifolia (CCDD) crosses produced through embryo culture. The average number of chromosome pairs in the O. sativa × O. latifolia regenerants ranged from 13.79 to 14.79. Ten to 18 bivalents were observed per cell. The average number of bivalents in the O. glumaepatula × O. latifolia regenerants ranged from 12.44 to 13.87, with 10–17 bivalents per cell. Some desynapsis occurred but 10 to 12 true bivalents remained at late metaphase in most cells. The high number of bivalents observed in the hybrids from these divergent parents indicates that a genetic system for pairing control similar to that in Triticum may be present in the Oryza genus.Key words: Oryza, embryo culture, meiosis.

Tetrasomic inheritance and chromosome pairing behaviour in the naturally occurring autotetraploid Heuchera grossulariifolia (Saxifragaceae)

Genome ◽  
1989 ◽  
Vol 32 (4) ◽  
pp. 655-659 ◽  
Author(s):  
Paul G. Wolf ◽  
Pamela S. Soltis ◽  
Douglas E. Soltis
Keyword(s):  
Chromosome Pairing ◽  
Meiotic Chromosome ◽  
Low Frequency ◽  
Small Chromosome ◽  
Tetrasomic Inheritance ◽  
Naturally Occurring ◽  
Chromatid Segregation ◽  
Marker Loci ◽  
Allozyme Loci ◽  
Pairing Behaviour

Inheritance patterns at four allozyme loci and chromosome pairing behaviour at diakinesis were examined in the naturally occurring autotetraploid Heuchera grossulariifolia. Segregation patterns for Tpi, Pgi, Pgm-2, and Lap deviated significantly from all possible disomic models. All patterns were consistent with tetrasomic inheritance of these marker loci. No chromatid segregation was detected electrophoretically. Meiotic chromosome configurations at diakinesis in 45 cells were compared with a previously published model to test for autopolyploid-like chromosome pairing. Using the observed chiasma frequencies, the frequency of quadrivalents was consistent with the expectations for an autotetraploid. We suggest that the low frequency of quadrivalents at diakinesis in Heuchera grossulariifolia is due to small chromosome size, which results in a low chiasma frequency.Key words: autopolyploidy, tetrasomic inheritance, chromosome pairing, isozyme genetics, Heuchera.

scholarly journals EM analysis of meiotic chromosome pairing in a pentaploid Achillea hybrid

Heredity ◽  
1990 ◽  
Vol 65 (1) ◽  
pp. 11-20 ◽  
Author(s):  
J Loidl ◽  
F Ehrendorfer ◽  
D Schweizer
Keyword(s):  
Chromosome Pairing ◽  
Meiotic Chromosome ◽  
Meiotic Chromosome Pairing
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