Narasinga Rao, P.S.R.L. and Sybenga, J. (1984) Linear orientation of trivalents and quadrivalents in late metaphase I pollen mother cells of pearl millet. Canadian Journal of Genetics and Cytology, 26 (5). pp. 506-510.
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Abstract
In a heterozygous telocentric substitution line of Pennisetum americanum, Robertsonian (= centric split) trivalents, trisomic trivalents, and tetrasomic ring quadrivalents showed linear or indifferent orientation frequencies of 1/3 at late metaphase I. This fitted a model which assumes sequential centromere activation in the multivalent, with random order of activation and a sufficiently long interval to permit stable coorientation of any two early centromeres before the following centromere is activated. A late centromere trapped between two coorienting early ones would thus be prevented from orientation. Reorientation in pearl millet, when it occurs, is late in these configurations. Chain quadrivalents had fewer linear but more indifferent orientations than the expected frequencies of 1/6 and 1/3, respectively. In the telocentric substitution line of rye examined, linear orientation of Robertsonian trivalents was practically absent, presumably owing to insufficiently long intervals between centromere activations, and to early reorientation. A reduction in interval length between centromere activations is assumed to accompany the stabilization of autotretraploids.
| Item Type: | Article |
|---|---|
| Author Affiliation: | Andhra University, Agricultural University, Wageningen |
| Subjects: | Crop Improvement |
| Divisions: | Millet |
| Depositing User: | Mr. SanatKumar Behera |
| Date Deposited: | 20 May 2012 07:21 |
| Last Modified: | 20 May 2012 07:21 |
| URI: | http://eprints.icrisat.ac.in/id/eprint/5520 |
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