Comparative karyological analysis of Indian Amorphophallus (Araceae)

Abstract

Comparative karyotypes of 22 accessions (14 species and six varieties) of Indian Amorphophallus (Araceae) are provided to deduce species interrelationships. Chromosome numbers for A. hirsutus, A. nicolsonianus and A. sp. are reported for the first time. Also, a new triploid cytotype of A. konkanensis was found. The diploid number 2n = 2x = 26 was noted in 13 taxa whereas 2n = 2x = 28 in three taxa. Six taxa exhibited 2n = 3x = 39 chromosomes. The highest mean chromosome length (MCL) was recorded in A. nicolsonianus (9.70 µm) and the lowest in A. paeoniifolius var. campanulatus (3.26 µm). Amongst all the taxa, the karyotypes of A. bonaccordensis and A. smithsonianus are unusual as they possess subtelocentric chromosomes. Multivariate analysis of taxa based on six karyological parameters (2n, x, THL, MCA, CVCL and MCL) revealed three clusters. Species of different sections (Amorphophallus, Conophallus and Rhaphiophallus) grouped together indicating that the sections that were generated based on morphological similarity do not reflect the phylogeny of the genus. Our studies suggest the need for comprehensive phylogenetic analyses of Indian Amorphophallus to understand interspecific relationships. Furthermore, it is recommended that genomic in-situ hybridization (GISH) studies should be conducted to understand the origin and nature of triploids in the genus.