Genefic Diversity of Gum Arabic-producing Acacia senegal Variefies in Kenya using Inter-Simple Sequence Repeat (ISSR) and Chloroplast Simple Sequence

Abstract

Acacia senegal is a drought-tolerant, multi-purpose tree species, highly valued for gum arabic production and increasingly being used in agro-forestry in Sub-Saharan Africa. Despite its long history of use, there has not been exhaustive genetic evaluation of the extant genetic resource base of A. senegal in Kenya for genetic improvement of the species. Inter-simple sequence repeat (ISSR) and chloroplast microsatellite (cpSSR) markers were used to study genetic diversity among seven Kenyan populations of A. senegal embracing three putative varieties: kerensis, leiorhachis and senegal. The two marker types detected similar levels of Nei’s gene diversity (HISSR = 0.211, HcpSSR = 0.212) among the A. senegal populations. Acacia senegal var. kerensis exhibited the highest diversity using ISSR markers (HISSR = 0.248), followed by varieties leiorhachis (HISSR = 0.218) and senegal (HISSR = 0.151). Analysis of molecular variance (AMOVA) detected significant genetic variations within and among populations (P < 0.001 and P < 0.01 for ISSR and cpSSR, respectively). Based on the unweighted pair group method with arithmetic mean (UPGMA) dendrogram of the seven populations, two regions were differentiated (north and south). Both markers demonstrated their potential for delineating population structure at local and regional levels, and infra-specific relations within the species, hence their potential as tools for conservation, improvement programmes and sustainable use of the species. This study provides baseline genetic information for the domestication of A. senegal varieties in Kenya.