The cross between Cenchrus purpureum (Schumach.) (Napier grass) and Cenchrus americanus (L.) Morrone (pearl millet) produce triploid and sterile hybrids. Chromosome doubling used to restore the fertility of the triploid hybrids produces hexaploid material that are mixoploid, but with desirable forage characteristics. Even backcrosses result in tetraploid and pentaploid mixoploid materials. The aim of this study was to compare the frequency of chromosome abnormalities in somatic cells of hybrids originated by backcross to compare with those found in synthetic hexaploid hybrids finding if there is a most stable material. To identify the abnormalities it was used the genomic in situ hybridization. The cell cycle analysis revealed similar frequencies and types of alterations both in the hexaploid and in hybrids originating from backcrosses. Chromosome elimination was reported in all types of hybrids. It was found micronuclei, notoriented chromosomes at metaphase, lost chromosome at anaphase/telophase and bridges at anaphase involving chromosomes from Napier grass and pearl millet in all hybrids analyzed independently of ploidy level.
Keywords: Pearl millet, Napier grass, chromosome alterations; chromosome elimination; micronucleus
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