PHYLOGENETIC ANALYSIS OF THE SELECTED GENERA OF FAMILY RHAMNACEAE BASED ON atpB PROMOTER REGION

Abstract

The family Rhamnaceae also known as “Buckthorn family” is a cosmopolitan family comprises of 52 genera and 900 to 950 species including both temperate and tropical trees, vines, and some shrubs distributed almost worldwide, and is highly famous for its significant importance in pharmaceutical industry. In the present study atpB gene promoter was amplified and sequenced from eighteen different species of Rhamnaceae and the sequenced data was further analyzed by various bioinformatics tools. The study was aimed to perform the systematic investigation of the selected genera of Rhamnaceae based on atpB gene promoter sequence and 72 micro and macro-morphological characters. About 72 morphological characters of taxonomic importance were selected from the Flora of Pakistan, which were used to construct a morphology based phylogeny. The phylogenetic tree based on atpB gene promoter was also constructed using MEGA6. In a separate Neighbor-joining analysis (comprised of six different genera) yield a number of stable clades with a high bootstrap support. Clade I comprising of genus Ziziphus, Sageretia and Berchemia received a high support based on atpB gene promoter which is also in agreement with 72 different morphological characters confirming their exact positions in the phylogenetic tree. Clade II comprised of Rhamnus also showed a high support confirming their exact position in the phylogenetic tree. Rhamnella gilgitica and Helinus lanceolatus has received distinct positions from all other species, because there is only a single species under investigation in these genera. The molecular and morphological systematics techniques bear their own advantages and disadvantages. Phylogenetic studies cannot be dependent just on molecular or morphological investigations but both should be considered in a phylogenetic study. Resolution among several groups (such as inter-generic relationships of selected genera was found to be much improved in combined analysis based on atpB gene promoter and 72 different morphological characters as compared to previous phylogenies, based on nuclear regions. It may be suggested that atpB gene promoter should be used as a barcode in the identification of plant species.