Karyological Studies on Four South Indian Species of Amorphophallus

Abstract

Karyotypes of four species of Amorphophallus indigenous to South India have been studied. The chromosome numbers observed are 2n=26 in A. hohenackeri, 2n=28 in A. campanulatus and A. dubius and 2n=39 in A. bulbifer. Meiosis is normal in A. campanulatus and 14 bivalents are observed at first metaphase.
Since 8 out of 10 species so far studied have 2n=26 or 39, the original basic number of the genus appears to be 13 from which x=14 in two species may have been derived by aneuploid gain of a pair of chromosomes.
A. hohenackeri has larger chromosomes and more symmetrical karyotype than the other species. The close phylogenetic relationship of A. campanulatus and A. dubius indicated by their morphological characters is further supported by the similarity exhibited by their karyotypes. In A. bulbifer (2n=3x=39) the chromosomes of the three genomes of the triploid cannot be matched into groups of three homologues. Karyotype analysis suggests either extensive chromosome repatterning or that A. bulbifer is an allotriploid with two genomes derived from one species and the other from a different species.