Assessment Of Species Boundaries Of The Moringa Ovalifolia (Dinter & A. Berger) In Namibia Using Nuclear Its Dna Sequence Data

ABSTRACT

The genus Moringa comprises of thirteen (13) species of trees and shrubs, widely distributed in the tropical and subtropical regions. For its size, this genus is one of the phenotypically varied group of angiosperms whose members are mostly sought after for nutritional, nutraceutical and industrial uses. The aim of this study was to assess the species boundaries of Moringa ovalifolia in Namibia by using the nuclear Internal Transcribed Spacer (ITS) sequenced data analysis. A total of seventeen (17) edited sequences of M. ovalifolia together with thirteen (13) other sequences of Moringa retrieved from NCBI were used to construct phylogenetic trees in Molecular Evolutionary Genetic Analysis software version 6.0 (MEGA). The phylogenetic trees were resolved using Neighbor-joining method, Maximum Parsimony method, Maximum Likelihood method based on the Tamura-Nei and the bootstrap consensus tree was determined from 500 replicates that represented the evolutionary history of the taxa analyzed. The nuclear ITS molecular marker successfully delimited species boundaries of M. ovalifolia specimens that were investigated in this study. The topology of all three phylogenetic trees generated by the three methods were similar. All sequences of M. ovalifolia under investigation and those retrieved from NCBI) were grouped together and are not nested with other Moringa species. The different populations of the Namibian M. ovalifolia are not phylogenetically different though geographically isolated. This means that the Namibian M. ovalifolia is a taxonomically ‘good species’. The study demonstrated the useful role of ITS in determining the species boundaries of populations. It is recommended that efforts be made to initiate domestication and breeding programs of the Namibian M. ovalifolia.