Identification of specific markers linked to regional differentiation of warbuia ugandensis in Kenya
Ochieng', Noel Onyango
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Warburgia ugandensis Sprague is an important medicinal tree with a restricted distribution in the tropical afro-alpine environment of Africa. The species population in Kenya has shown a high genetic differentiation with respect to the Rift Valley. The kind of differentiation indicated a possible allopatric speciation which may confer species adaptation advantages. The objective of the study was to identify specific genetic markers linked to the regional differentiation of W. ugandensis within and across Kenyan Rift Valley. Nine populations of W. ugandensis were analysed by an adaptation of Bulk Segregant Analysis employing Random Amplified Polymorphic DNA (RAPD) marker technique. Five primers showed putative East and West genetic differentiation. The diagnostic markers were isolated, cloned into a pGEM-T ® vector and confirmed by sequencing. The resulting sequences were analysed by searching for similarity from the genomic databases of National Centre of Biotechnology Institute (NCB I) using BLAST algorithm. Of the 5 sequencing products, only 3 (WarburgiaIC15E, WarburgiaIC55E and WarburgiaIC28W) showed significant association with plants and bacteriallike chromosomal sequence homolog's with very low E-values. A sequence alignment from CLUSTALW showed significant conserved protein regions or domain of both plants and some bacteria like sequences. Phylogenetic anylysis revealed high rates of genetic distances (of an average 0.8) and a low rate of disparity indices of (0), suggesting some evolutionary forces behind the demographic differentiation. These results imply that the genetic differentiation observed among W. ugandensis population in Kenya may be as a result of genetic mutants (eg Transposable Elements) in certain domains of the chromosome. This may have some implication on genome functionality, although not confirmed in this study.