Abstract
The frequency distributions of certain homologous and non-homologous chromosomes in somatic cells of diploid and liexaploid species of Avena were studied and compared with the theoretical random distribution.
All homologous chromosomes studied irrespective of shape and size showed non-random distribution in both diploid and hexaploid species. In all cases the homologous chromosomes were closer than would be expected with random distribution. Chromosomal characters such as size, shape, and presence or absence of nucleolar organizing regions did not exert appreciable influence on the somatic association of homologues.
While the non-homologues followed the theoretical random distribution in diploid species, a significant deviation from the random curve was noted for non-homologues in hexaploid species. However, diploid and hexaploid non-homologous chromosomes had characteristic “S”-shaped cumulative frequency distributions which were distinct from the “half-moon”-shaped ones obtained for homologous chromosomes.
The different regions (short arm, long arm, centromere and mid-points) of two pairs of homologous chromosomes (one of them being nucleolar) studied showed non-random distribution with the exception of the long arm of the non-nucleolar chromosome. From these results the role of the centromere or mutual attraction of homologous segments could not be assessed with certainty.
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Contribution No. 232 from the Research Station, Central Experimental Farm, Ottawa, Ontario, Canada.
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Sadasivaiah, R.S., Watkins, R. & Rajhathy, T. Somatic association of chromosomes in diploid and hexaploid Avena . Chromosoma 28, 468–481 (1969). https://doi.org/10.1007/BF00284262
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DOI: https://doi.org/10.1007/BF00284262