Supernumerary chromosomes and chiasma distribution in Triticum speltoides

Zarchi, Y.; Hillel, J.; Simchen, Giora

doi:10.1038/hdy.1974.85

Cited by 17 publications

(8 citation statements)

References 8 publications

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“…Increases in mean cell chiasma frequency generally result in chiasmata being formed in these interstitial regions with concommitant breakup of supergene complexes normally inherited as units. Again this situation is similar to that described in Lolium and Festuca by Rees and Dale (1974), in wheat by Zarchi et a!., (1972Zarchi et a!., ( , 1974 and in rye by Jones (1974).…”

Section: Resultssupporting

confidence: 71%

Chiasma frequency and variability of morphological characters in populations of two grasshopper species

Westerman

1983

Heredity

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Section: Resultssupporting

confidence: 71%

Chiasma frequency and variability of morphological characters in populations of two grasshopper species

Westerman

1983

Heredity

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“…Two A-genome chromosomes carrying Spelt 52 blocks also have Spelt 1 blocks (arrows), indicating A t -G translocation. Species-specific translocation 6A t /1G revealed by GISH is indicated by arrows ary Bs (Mendelson and Zohary 1972;Zarchi et al 1974;Cebria et al 1994;Puertas 2002;Jones and Houben 2003;Jones et al 2008a, b;Carchilan et al 2009;Belyayev et al 2010). We detected one to seven B-chromosomes in different populations of Ae.…”

Section: Discussionmentioning

confidence: 83%

Tandem repeats on an eco-geographical scale: outcomes from the genome of Aegilops speltoides

2011

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The chromosomal pattern of tandem repeat fractions of repetitive DNA is one of the most important characteristics of a species. In the present research, we aimed to detect and evaluate the level of intraspecific variability in the chromosomal distribution of species-specific Spelt 1 and Aegilops-Triticum-specific Spelt 52 tandem repeats in Aegilops speltoides and in closely related diploid and polyploid species. There is a distinct eco-geographical gradient in Spelt 1 and Spelt 52 blocks abundance in Ae. speltoides. In marginal populations, the number of Spelt 1 chromosomal blocks could be 12-14 times lower than in the center of the species distribution. Also, in related diploid species, the abundance of Spelt 52 correlates with evolutionary proximity to Ae. speltoides. Finally, the B- and G-genomes of allopolyploid wheats have Spelt 1 chromosomal distribution patterns similar to those of the types of Ae. speltoides with poor and rich contents of Spelt 1, respectively. The observed changes in numbers of blocks of Spelt 1 and Spelt 52 tandem repeats along the eco-geographical gradient may due to their depletion in the marginal populations as a result of increased recombination frequency under stressful conditions. Alternatively, it may be accumulation of tandem repeats in conducive climatic/edaphic environments in the center of the species' geographical distribution. Anyway, we observe a bidirectional shift of repetitive DNA genomic patterns on the population level leading to the formation of population-specific chromosomal patterns of tandem repeats. The appearance of a new chromosomal pattern is considered an important factor in promoting the emergence of interbreeding barriers.

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“…In Triticum speltoides, Zarchi et al (1974) observed that terminal chiasmata are reduced and interstitial chiasmata are increased in B-carriers. According to these authors, either the Bs exercise direct genetic control on chiasma distribution, or else they change the time-table of meiosis in such a way that pairing and/or chiasma terminalization are not completed.…”

Section: Discussionmentioning

confidence: 96%

The effect of B-chromosomes on A-chromosome chiasma formation in pearl millet.

Jayalakshmi

Pantulu

1984

CYTOLOGIA

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Pantulu and Manga (1975) studied the influence of standard B-chromosomes while Subba Rao and Pantulu (1978) studied the effect of the derived B-chromosomes on mean cell chiasma frequency in pearl millet, Pennisetum typhoides (Burm.) S. & H. (2n=14). No critical assessment of the effects of Bs on A-chromosome chiasma distribution is, however, available. This information is of interest because when there is a distal localization of chiasma formation as is the case in pearl millet, the occurrence of interstitial chiasmata may bring about a recombination of otherwise tigtly linked genes (Rees and Jones 1977). Particular attention has therefore been paid in this paper to the effect of B-chromosomes on chiasma distribution.In an earlier paper, Subba Rao and Pantulu (1978) speculated that the differenti al effects of the three types of Bs present in pearl millet on A-chiasma frequency were due to relative amounts of euchromatin and heterochromatin present in them. This conclusion was arrived at particularly from the effects observed when the three types of Bs were present in different combinations and ratios.The B-chromosomes of pearl millet are, however, unstable and exhibit numeri cal variation between cells of the same tissue and between tissues of the same plant (Jayalakshmi and Pantulu 1982). The earlier workers carried out observations and analyses at the individual plant level. For this purpose, they classified the B-carry ing plants on the basis of 'modal' number, i.e., that number which is most frequent. How far the Bs present in numbers deviating from the modal number are liable to influence the results is not known. In the present study, therefore, analyses were carried out after pooling the cells with the same B-chromosome type and number from different plants.

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Supernumerary chromosomes and chiasma distribution in Triticum speltoides

Cited by 17 publications

References 8 publications

Chiasma frequency and variability of morphological characters in populations of two grasshopper species

Chiasma frequency and variability of morphological characters in populations of two grasshopper species

Tandem repeats on an eco-geographical scale: outcomes from the genome of Aegilops speltoides

The effect of B-chromosomes on A-chromosome chiasma formation in pearl millet.

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