Molecular analyses of genetic variation and phylogenetic relationship in Indian soap nut (Sapindus L.) and closely related taxa of the family Sapindaceae

Molecular differentiation and phylogenetic relationships of Indian Sapindus and its closely allied taxa of the family Sapindaceae was studied using nuclear ribosomal DNA of internal transcribed spacer (ITS). Evolutionary divergence over sequence pairs between the tribes of the family Sapindaceae was estimated, and maximum divergence (0.20) was observed between the tribes, Paullinieae and Harpullieae, whereas the lowest (0.06) was found between Sapindeae and Lepisantheae. Phylogenetic tree based on maximum likelihood method revealed the separation of all three species of the Sapindus in different clusters. S. delavayi a Japanese species, showed a close affinity to the S. mukorossi with high bootstrap support (99%). There is a significant distinction between S. emarginatus and S. trifoliatus with high (99%) bootstrap support in the clade. It clearly indicates that both the species are distinct and no infra-specific categories existed among these taxa. ITS region has shown a reliable marker to differentiate different taxa considered in the present study. Furthermore, studies on comparative phylogenomics of different taxa might provide useful insight to understand the phylogeny of the family Sapindaceae in a more comprehensive way.