Chromosome pairing and chiasma formation in autopolyploids of different Lathyrus species

Genome ◽  
1997 ◽  
Vol 40 (6) ◽  
pp. 937-944 ◽  
Author(s):  
H. I. T. Khawaja ◽  
J. Sybenga ◽  
J. R. Ellis
Keyword(s):  
Gene Flow ◽  
Chromosome Pairing ◽  
Chiasma Frequency ◽  
Chiasma Formation ◽  
Meiotic Metaphase ◽  
Lathyrus Sativus ◽  
Ploidy Levels ◽  
Lathyrus Odoratus ◽  
Mixed Populations ◽  
Tetraploid Level

Chromosome pairing and chiasma formation were studied in natural and induced tetraploids (2n = 28) of Lathyrus odoratus (induced), Lathyrus pratensis (natural and induced), Lathyrus sativus (induced), and Lathyrus venosus (natural), as well as in triploids of L. pratensis and diploids of L. odoratus, L. pratensis, and L. sativus. All natural tetraploids appeared to be autotetraploids and their meiotic metaphase I behaviour was very similar to that of the induced autotetraploids, with average numbers of pairing partner switches exceeding 4 or even 5. Multivalent frequencies were high, but the numbers of chiasmata were not much higher than necessary to maintain the configurations. Interstitial chiasmata were common, but not predominant. Fertility was reduced, but sufficient for predominantly vegetatively reproducing species. The triploids of L. pratensis had an even higher multivalent frequency than the tetraploids, but still produced some viable progeny at or close to the tetraploid level, suggesting that in mixed populations of diploids and tetraploids, triploids can contribute to gene flow between the ploidy levels. There was no significant correlation between chiasma frequency and ring bivalent frequency in the diploids and multivalent frequency in the corresponding tetraploids. In the tetraploids, chiasma frequency and multivalent frequency were negatively correlated.Key words: Lathyrus, natural, induced, autotetraploid, triploid, meiosis.

Comparative analysis of female and male meiosis in three meiotic mutants of tomato

Genome ◽  
1997 ◽  
Vol 40 (6) ◽  
pp. 879-886 ◽  
Author(s):  
Francis W. J. Havekes ◽  
J. Hans de Jong ◽  
Christa Heyting
Keyword(s):  
Comparative Analysis ◽  
Chromosome Pairing ◽  
Meiotic Prophase ◽  
Chiasma Frequency ◽  
Chiasma Formation ◽  
Male Meiosis ◽  
Wild Type ◽  
Female Meiosis ◽  
Similar Reduction ◽  
Meiotic Mutants

Female meiosis was analysed in squash preparations of ovules from three meiotic mutants and wild-type plants of tomato. In the completely asynaptic mutant as6, chromosome pairing and chiasma formation were virtually absent in both sexes. In the partially asynaptic mutant asb, with intermediate levels of chromosome pairing at pachytene, there were a higher number of chiasmate chromosome arms in female meiosis than in male meiosis, whereas in the desynaptic mutant as5 there were normal levels of chromosome pairing at pachytene and a similar reduction in chiasma frequency in the two sexes. In wild-type tomato, we found slightly higher numbers of chiasmate chromosome arms in female meiosis than in male meiosis. We propose that the higher female chiasma frequencies in mutant asb and wild-type tomato result from a longer duration of female meiotic prophase. This would allow chromosomes more time to pair and recombine. It is possible that a longer duration of prophase I does not affect mutants as5 and as6, either because the meiotic defect acts before the pairing process begins (in as6) or because it acts at a later stage and involves chiasma maintenance (in as5).Key words: female meiosis, tomato, chiasma, mutant.

scholarly journals Evidence of premeiotic control of chromosome pairing in Triticum aestivum

1972 ◽  
Vol 20 (2) ◽  
pp. 201-212 ◽  
Author(s):  
M. W. Bayliss ◽  
Ralph Riley
Keyword(s):  
Chromosome Pairing ◽  
Chiasma Frequency ◽  
Sequential Sampling ◽  
Chiasma Formation ◽  
Temperature Sensitive ◽  
Final Temperature ◽  
Similar Time ◽  
Temperature Changes ◽  
Critical Range ◽  
Sensitive Stage

SUMMARYA genotype of wheat deficient for a pair of chromosomes stabilizing chiasma frequency against extremes of temperature was investigated to determine the position and duration of temperature sensitivity with respect to first metaphase of meiosis. Temperature changes over a critical range, followed by sequential sampling and measurement of chiasma frequency, showed a relatively short temperature-sensitive stage, the position and duration of which were dependent on the final temperature used. Comparison with meiotic timings made independently showed that the temperature-sensitive stage occurred in the premeiotic interphase. Euploid wheat was shown to have a stage in chiasma formation sensitive to high-temperature treatments at a similar time.Comparison with the work of others showed that the sensitive stage lay between the last premeiotic mitosis and the start of DNA synthesis. This modification of chromosome pairing at a much earlier stage than has been previously demonstrated is further evidence that the processes of chromosome pairing and crossing-over are probably more complex than formerly envisaged.

An experimental analysis of bivalent interlocking in spermatocytes of the new Triturus vulgaris

1979 ◽  
Vol 37 (1) ◽  
pp. 125-141
Author(s):  
H.G. Callan ◽  
S.M. Pearce
Keyword(s):  
Heat Shock ◽  
Synaptonemal Complex ◽  
Nuclear Membrane ◽  
Experimental Analysis ◽  
Chiasma Frequency ◽  
Chiasma Formation ◽  
Meiotic Metaphase ◽  
Frequency Of Occurrence ◽  
Late Pachytene ◽  
Triturus Vulgaris

Interlocked bivalents at 1st meiotic metaphase are relatively uncommon in spermatocytes of the newt Triturus vulgaris, but their frequency of occurrence can be significantly increased by subjecting newts to a 24-h heat shock. Newt spermatocytes are sensitive to a heart shock at any stage between the end of premeiotic S and mid to late pachytene. The heat shock does not cause evidence desynapsis, nor does it significantly affect chiasma frequency; therefore the interlocked condition induced in spermatocytes which were subjected to a heat shock when they were in zygotene or pachytene is unlikely to be a consequence of synaptic trapping. By way of explanation it is suggested that a heat shock may cause telomers to detach from the nuclear membrane, or from the synaptonemal complex where the latter is attached to the membrane, thus allowing non-homologous chromonemata to become interwined before chiasmata have formed. If this explanation is valid, it is then further suggested that the recombination process which results in chiasma formation probably takes place in chromosomal regions lying outside the synaptonemal complex, rather than inside, between its 2 lateral elements.

GENETIC RELATIONSHIPS BETWEEN DIPLOIDS AND TETRAPLOIDS IN SERIES EUBARBATAE OF AVENA

1968 ◽  
Vol 10 (1) ◽  
pp. 68-81 ◽  
Author(s):  
Gideon Ladizinsky ◽  
Daniel Zohary
Keyword(s):  
Gene Flow ◽  
Genetic Relationships ◽  
Extreme Case ◽  
Meiotic Behavior ◽  
Ploidy Levels ◽  
Single Genome ◽  
In Series ◽  
Full Shift ◽  
Tetraploid Level ◽  
Diploid Level

Diploid (2n = 14) and tetraploid (2n = 28) entities in series Eubarbatae of the genus Avena have been found to be genetically closely linked and are regarded as a single polyploid complex. At both ploidy levels the various morphological types are interfertile. Diploids and tetraploids are largely sympatric in their distribution and converge considerably in their ranges of morphological variation. Contacts between diploids and tetraploids are common and blurred morphological boundaries characterize mixed populations.The possibility of gene flow between diploids and tetraploids has been indicated by the behavior of triploid F1 hybrids. Such hybrids have been found to be partially fertile. In their progeny a conspicuous restoration of fertility is apparent: numerous plants of the F2 generation have been stabilized around the tetraploid level, few around the diploid level. In contact areas, triploids can be regarded as efficient bridges of gene flow between the two ploidy levels.The range of variation found at the tetraploid level is fully explicable by the variation present in the diploid races. Tetraploids are therefore regarded to have had an inter-varietal origin, i.e. have evolved from a single genome. They apparently represent an extreme case of bivalentization, where a full shift from an autotetraploid to an allotetraploid meiotic behavior had occurred. Meiotic behavior of the F2 plants also indicate such origin.

The effect of increased dosage of wheat chromosomes on chromosome pairing and an analysis of the chiasma frequencies of individual wheat bivalents

1985 ◽  
Vol 27 (4) ◽  
pp. 421-425 ◽  
Author(s):  
T. E. Miller ◽  
S. M. Reader
Keyword(s):  
Spring Wheat ◽  
Chromosome Pairing ◽  
Chinese Spring ◽  
Chiasma Frequency ◽  
Wheat Chromosome ◽  
Chiasma Formation ◽  
Homologous Pair ◽  
Chinese Spring Wheat

By crossing the 'Chinese Spring' wheat tetrasomic series with rye, 21 different hybrid genotypes were produced, each with a single different homologous pair of wheat chromosomes. These hybrids enable the effect on chromosome pairing to be assessed for an extra dose of each of the 21 chromosomes. Significant effects were observed with eight of the chromosomes. Chiasma frequencies for each of the 21 pairs of chromosomes were also studied and the differences between the chromosomes were reported. The correlation between chromosome pairing and chiasma formation and chiasma frequency differences between bivalents and genomes are discussed.Key words: wheat, chromosome pairing, chiasma frequencies.

Rapid cytological diploidization in newly formed allopolyploids of the wheat (Aegilops-Triticum) group

Genome ◽  
2009 ◽  
Vol 52 (11) ◽  
pp. 926-934 ◽  
Author(s):  
Hakan Ozkan ◽  
Moshe Feldman
Keyword(s):  
Chromosome Pairing ◽  
Dna Sequences ◽  
Meiotic Metaphase ◽  
Epigenetic Changes ◽  
Noncoding Dna ◽  
Ploidy Levels ◽  
Seed Fertility ◽  
Positive Linear Relationship ◽  
Competitive Species ◽  
Homoeologous Chromosomes

Recent studies in the genera Aegilops and Triticum showed that allopolyploid formation triggers rapid genetic and epigenetic changes that lead to cytological and genetic diploidization. To better understand the consequences of cytological diploidization, chromosome pairing and seed fertility were studied in S1, S2, and S3generations of 18 newly formed allopolyploids at different ploidy levels. Results showed that bivalent pairing at first meiotic metaphase was enhanced and seed fertility was improved during each successive generation. A positive linear relationship was found between increased bivalent pairing, improved fertility, and elimination of low-copy noncoding DNA sequences. These findings support the conclusion that rapid elimination of low-copy noncoding DNA sequences from one genome of a newly formed allopolyploid, different sequences from different genomes, is an efficient way to quickly augment the divergence between homoeologous chromosomes and thus bring about cytological diploidization. This facilitates the rapid establishment of the raw allopolyploids as successful, competitive species in nature.

A Demonstration of a 1:1 Correspondence Between Chiasma Frequency and Recombination Using a Lolium perenne/Festuca pratensis Substitution

Genetics ◽  
2002 ◽  
Vol 161 (1) ◽  
pp. 307-314 ◽  
Author(s):  
J King ◽  
L A Roberts ◽  
M J Kearsey ◽  
H M Thomas ◽  
R N Jones ◽  
...  
Keyword(s):  
Lolium Perenne ◽  
Chiasma Frequency ◽  
Chiasma Formation ◽  
Grass Species ◽  
Festuca Pratensis ◽  
Single Chromosome ◽  
Length Polymorphisms ◽  
Amplified Fragment Length Polymorphisms ◽  
Frequency Counts

Abstract A single chromosome of the grass species Festuca pratensis has been introgressed into Lolium perenne to produce a diploid monosomic substitution line (2n = 2x = 14). The chromatin of F. pratensis and L. perenne can be distinguished by genomic in situ hybridization (GISH), and it is therefore possible to visualize the substituted F. pratensis chromosome in the L. perenne background and to study chiasma formation in a single marked bivalent. Recombination occurs freely in the F. pratensis/L. perenne bivalent, and chiasma frequency counts give a predicted map length for this bivalent of 76 cM. The substituted F. pratensis chromosome was also mapped with 104 EcoRI/Tru91 and HindIII/Tru91 amplified fragment length polymorphisms (AFLPs), generating a marker map of 81 cM. This map length is almost identical to the map length of 76 cM predicted from the chiasma frequency data. The work demonstrates a 1:1 correspondence between chiasma frequency and recombination and, in addition, the absence of chromatid interference across the Festuca and Lolium centromeres.

EST-SSR analysis provides insights about genetic relatedness, population structure and gene flow in grass pea (Lathyrus sativus)

2015 ◽  
Vol 134 (3) ◽  
pp. 338-344 ◽  
Author(s):  
Khela R. Soren ◽  
Ashutosh Yadav ◽  
Gaurav Pandey ◽  
Priyanka Gangwar ◽  
Ashok K. Parihar ◽  
...  
Keyword(s):  
Population Structure ◽  
Gene Flow ◽  
Genetic Relatedness ◽  
Lathyrus Sativus ◽  
Grass Pea ◽  
Ssr Analysis

Estimating meiotic chromosome pairing and recombination parameters in telocentric trisomics

Genome ◽  
2007 ◽  
Vol 50 (11) ◽  
pp. 1014-1028 ◽  
Author(s):  
J. Sybenga ◽  
H. Verhaar ◽  
D.G.A. Botje
Keyword(s):  
Gene Transfer ◽  
Chromosome Pairing ◽  
Genome Analysis ◽  
Meiotic Chromosome ◽  
Chiasma Formation ◽  
Chromosome Morphology ◽  
Test Material ◽  
Gene Localization ◽  
Maximum Information ◽  
Chromosome 1R

Telocentric trisomics (telotrisomics; one arm of a metacentric chromosome present in addition to two complete genomes) are used in theoretical studies of pairing affinities and chiasma formation in competitive situations and applied in genome analysis, gene localization, gene transfer, and breakage of close linkages. These applications require knowledge of the recombination characteristics of telotrisomics. Appropriate cytological and molecular markers and favorable chromosome morphology are not always available or applicable for quantitative analyses. We developed new mathematical models for extracting the maximum information from simple metaphase I observations. Two types of telotrisomics of the short arm of chromosome 1R of rye ( Secale cereale ), including several genotypes, were used as test material. In simple telotrisomics, pairing between morphologically identical complete chromosomes was more frequent than pairing between the telocentric and either of the normal chromosomes. In the telocentric substitution, morphologically identical telocentrics paired less frequently with each other than either one with the normal chromosome. Pairing partner switch was significant. Interaction between the two arms was variable. Variation within plants was considerable. Telotrisomics without markers are suitable for analyzing pairing preferences, for gene localization and gene transfer, and for breaking tight linkages, but less so for genome analysis.

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