Morphological and molecular studies of three species of Boerhavia L. from Ile-Ife, Nigeria

Abstract

A wide range of plasticity and polymorphism have been documented in the genus Boerhavia. More so, the possible presence of natural hybrids  among the species of the genus has made species identification more difficult. This study employed morphological characters, pollen parameters as well as Random Amplified Polymorphic DNA (RAPD) to identify and elucidate the phylogenetic relationship that exists among the three species of Boerhavia distributed in Ile-Ife, Nigeria. Qualitative and quantitative morphological characters were observed and measured respectively. The acetolysis of the pollen grains was carried out according to Erdtman method. Fresh and young leaves of the Boerhavia species studied were  collected for genomic DNA extraction using modified Dellarpota procedure. The quality and concentration of DNA was assessed by gel electrophoresis on 2% agarose with known concentrations of undigested lambda DNA. Subsequently, the DNA quantification was done according to standard measurement. The Principal Components Analysis of the morphological traits and the pollen grain studies indicated that the three Boerhavia species studied have a very high level of relationship. However, the Single Linkage Cluster Analysis of the morphological data and the unweighted pair group method with arithmetic mean (UPGMA) cluster analysis of RAPD data revealed that B. erecta is distantly related to B. coccinea and B. diffusa. Despite the fact that the three Boerhavia species studied possess high level of similarity, they can still be distinguished from each other. In conclusion, B. coccinea and B. diffusa are more closely related to each other than B. erecta.

Key words: RAPD marker, Pollen grains, Phylogenetic relationship, Polymorphism