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.

Quantitative analysis of meiotic chromosome pairing in triploid blueberry: evidence for preferential pairing

Genome ◽  
1990 ◽  
Vol 33 (1) ◽  
pp. 60-67 ◽  
Author(s):  
Nicholi Vorsa
Keyword(s):  
Chromosome Pairing ◽  
Meiotic Chromosome ◽  
Chiasma Formation ◽  
Vaccinium Corymbosum ◽  
Preferential Pairing ◽  
Frequency Distributions ◽  
Meiotic Chromosome Pairing ◽  
Random Pairing ◽  
Random Frequency ◽  
Genome Divergence

Mathematical models have been developed to predict meiotic configuration frequency distributions for autoploid (random chromosome pairing) or preferential chromosome pairing behavior. Meiotic chromosome pairing was quantitatively analysed, relative to these models, in six highbush blueberry (Vaccinium corymbosum) triploid (2n = 3x = 36) hybrids derived from three unrelated 4x × 2x crosses. Mean trivalent per cell frequencies ranged from 3.59 to 7.89. Excess univalents were observed in triploids of one cross and are probably a result of disturbance in chiasma formation or maintenance and (or) random pairing failure. Arm chiasmate association values (a and b) ranged from 0.72 to 1.00, with the greatest difference in arm values being 0.18. Trivalent to ring bivalent (r) ratios ranged from 0.59 to 2.02. The observed configuration frequency distributions of three triploids having r-values greater than 1 did not deviate significantly from the autoploid pairing (p = 0) model frequency distribution. Frequency distributions of three triploids having r-values less than 1 deviated significantly from the autoploid model. Ranges for pairing affinity relationships include the possibility of two genomes pairing preferentially at a frequency of 77.7% (0.444 points over the random frequency of 0.333), which suggests the presence of genome divergence in blueberry. However, violation of model assumptions could seriously bias preferential pairing estimates. Segregating genetic factors also appear to be of significance in chromosome pairing behavior.Key words: autotriploids, chromosome pairing, preferential pairing, genome divergence, meiotic configurations.

scholarly journals Aneuhaploids in bread wheat

1976 ◽  
Vol 28 (1) ◽  
pp. 37-45 ◽  
Author(s):  
T. E. Miller ◽  
Victor Chapman
Keyword(s):  
Triticum Aestivum ◽  
Genetic Control ◽  
Bread Wheat ◽  
Chromosome Pairing ◽  
Chinese Spring ◽  
Meiotic Chromosome ◽  
Hordeum Bulbosum ◽  
Meiotic Abnormalities ◽  
Meiotic Chromosome Pairing

SUMMARYEuploid and aneuploid plants of Triticum aestivum, variety Chinese Spring were pollinated with, pollen of Hordeum bulbosum. Euhaploids and aneuhaploids of Chinese Spring were obtained from the crosses. Meiotic chromosome pairing was analysed in 25 different aneuhaploids and the results were compared with those obtained from euhaploids. The evidence provided by the meiotic studies was used to identify chromosomes whose activities affected the genetic control of chromosome pairing.Meiosis was abnormal in a 23-chromosome aneuhaploid and in the 22-chromosome sectors of a chimaeral plant. Both plants were thought to have resulted from the incomplete elimination of the genome of H. bulbosum from hybrid embryos. It is suggested that the meiotic abnormalities in the two aneuhaploids were caused by the residual barley chromosomes.

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.

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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