Cytomorphological studies of a spontaneous triploid in Pennisetum hohenackeri Hochst. ex Steud

During studies on the genomic relationships of the wild species of the genus Pennisetum, one spontaneous triploid (3x = 27) plant was identified among the diploid cytotypes (2n = 18) of Pennisetum hohenackeri Hochst. ex Steud. The triploid plant resembled the diploid in most morphological characters, except for the reduced number of spikelets. Chromosome associations of 9 II + 9 I were observed at diakinesis and metaphase I. The bivalents divided normally, while the univalents lagged and formed a separate nucleus, which was included in one of the daughter cells. On the basis of these studies, this plant was considered to be an allotriploid and might have originated as a spontaneous hybrid between diploid P. hohenackeri and an unknown tetraploid (amphidiploid) taxon with one of its genomes homologous to that of diploid P. hohenackeri. The possible donor of this genome could be P. orientale, which is a tetraploid with a basic chromosome number of x = 9.Key words: allotriploid, meiosis, diakinesis, univalents, micronuclei, laggard