Tissue-specific genome instability in synthetic interspecific hybrids of Pennisetum purpureum (Napier grass) and Pennisetum glaucum (pearl millet) is caused by micronucleation.

Genome instability is observed in several species hybrids. We studied the mechanisms underlying the genome instability in hexaploid hybrids of Napier grass (Pennisetum purpureum R.) and pearl millet (Pennisetum glaucum L.) using a combination of different methods. Chromosomes of both parental genomes are lost by micronucleation. Our analysis suggests that genome instability occurs preferentially in meristematic root tissue of hexaploid hybrids, and chromosome elimination is not only caused by centromere inactivation. Likely, beside centromere dysfunction, unrepaired DNA double-strand breaks result in fragmented chromosomes in synthetic hybrids.