Phylogenetic analyses and evolutionary relationships of Saraca asoca with their allied taxa (Tribe-Detarieae) based on the chloroplast matK gene

Abstract

Saraca asoca (Roxb.) Wilde, (Ashok) is a plant native to India and is popular for its anti-cancer, anti-menorrhagic, anti-oxytocic, anti-microbial activities having extended uses in ayurveda, unani and homeopathy. Partial chloroplast matK gene (900 bp) was PCR amplified, sequenced and used to investigate the evolutionary inter- relationships of Indian Saraca asoca with other members of the tribe Detarieae belonging to the subfamily Caesalpinioideae under the family Leguminosae. The sequence analysis of chloroplast matK belonging to 70 taxa exhibited 649 conserved sites, 244 variable sites and 119 parsimony informative sites. Average composition of nucleotides among taxa were found to be approximately, A-30.5 %, T-37.3 %, G-14.5 %, C-17.7 % and the transition/transversion ratio was 0.77, while the overall mean distance was 0.022 ± 0.002 on the basis of the number of substitutions. These analyses indicate that Saraca asoca may have passed through mostly synonymous substitution during evolution. Moreover, it is observed that the transitional substitution is more pronounced in 3rd codon position whereas transversions are saturated among all three codon positions. Eurypetalum tessmannii showed highest Disparity Index (DI = 0.06) with Saraca asoca. The close relationship of Saraca asoca was established with Saraca palembanica, Saraca declinata, Endertia spectabilis and Lysidice rhodostegia.