Chromosomal translocations in the evolution of Amorphophallus bonaccordensis from A. hohenackeri

• Two endemic species from Western Ghats, A. hohenackeri and A. bonaccordensis, were compared to trace their origin.
• The chromosome number in both were 2n = 26.
• Based on Stebbins classification A. bonaccordensis was advanced.
• The mitotic and meiotic abnormalities indicate occurrence of translocations in A. bonaccordensis.
• The ISSR analysis revealed more unique bands in A. bonaccordensis substantiating chromosomal rearrangements and high mutation of the SSR loci.

In present study we have made an attempt to trace possible lines in the evolution of A. bonaccordensis separating from A. hohenackeri, where translocations at the chromosomal level could have resulted in a shift of the habitat during evolution of A. bonaccordensis. This species is occurring as an endemic taxon at a higher altitude than it may have been the case with its ancestor that occupied lower altitudes and possibly a broader ecological niche. Morphological and physiological differences between the recent two closely related taxa, in spadix and appendix characters, corm flesh colour, pollen morphology and oxalate content, may be attributed also to the translocation at the cytological level. Detailed karyotype studies have been done in these Amorphophallus species from Southern Western Ghats, where they are critically endangered in their habitats, indicating that the chromosome number in both species is 2n = 26. In both of them there is a considerable variation in the karyotype symmetry. Accordingly, A. hohenackeri is placed under 2B whereas A. bonaccordensis fits well to 3B category of Stebbins’ classification. The highly endemic species Amorphophallus bonaccordensis, known only from the type locality, is supposed to have originated from A. hohenackeri via many cycles of translocations resulting in heteromorphic, nearly telocentric chromosomes, peculiar satellites, and many mitotic abnormalities like bridges, laggards, micronuclei and heteromorpic bivalents, terminalised chiasmata, supernumerary chromosomes and multinucleate cells at meiosis. ISSR analysis with 17 ISSR primers revealed a higher number of unique bands in A. bonaccordensis. Also the ISSR data, when correlated with the karyotype data, indicate that A. bonaccordensis has probably originated from A. hohenackeri due to chromosomal rearrangements and high mutation of the SSR loci.