Abstract

The karyomorphology of the cotton seed lily, Eriospermum abyssinicum Baker (family Eriospermaceae) was investigated through mitotic and meiotic studies. The chromosome complement was karyotypically analysed based on chromosome arm ratio and centromeric indices. The somatic chromosome complement of 2n = 24 recorded at metaphase I and the 12 bivalents at prophase I of meiosis suggested x = 6 basic chromosome number and paleopolyploidization process in the evolution of this species. There was no evidence of B chromosome or nucleolar-organizer in the complements. Variation in position of centromere ranged from the median to sub-median and sub-terminal. We found slight variation between some homologues in terms of lengths which suggest hybrid origin (allopolyploidy) of the genome. The microspore mother cell had normal meiosis with subsequent formation of 4 daughter nuclei and normal spores suggesting that the changes in chromosome behaviour occurred at very low frequency and these changes were transient with no evidence of phenotypic and genomic instability (aneuploidy) consequences. It was therefore inferred that the population of E. abyssinicum studied might have evolved through changes in chromosome structure or through natural hybridisation between closely related populations.

Key words: Eriospermum abyssinicum, lily, chromosome, karyotype.