Insight into the biology, genetics and evolution of the Centella asiatica polyploid complex in Madagascar

Centella asiatica is an important industrial crop in Madagascar that is collected in the wild for its triterpenic glycoside compounds. A multidisciplinary approach was applied to study diversity of 6 populations of C. asiatica. Cytogenetical approach and fluorescent in situ hybridization (FISH) analysis coupled with cytological evaluation of stomata density revealed diploid (2n = 2x = 18) and tetraploid (2n = 4x = 36) populations. Genetic diversity was evaluated through SSR analysis and indicates three separated groups, clearly distinct from Indian and South African genotypes. Chloroplast diversity analysis reveals two chlorotypes corresponding to diploid and tetraploid populations respectively, indicating an ancient origin of polyploidy. Triterpenic glycoside content of some clones was evaluated confirming that active compound content is highly variable. Implications of our results for further genetic studies and set-up breeding program are discussed.

► Populations of Centella asiatica of Madagascar are diploid (2n = 2x = 18) and tetraploid (2n = 4x = 36).
► Presence of two chlorotypes in Madagascar suggest ancient origin of polyploidy and at least two distinct populations.
► We examine genetic diversity through SSR analysis and C. asiatica from Madagascar are clearly separated from Indian and south African genotypes
► Triterpenic glycoside content is highly variable.