Genetic Variability Analysis of the Polyploid Complex of Acacia nilotica (L.) Willd. Using RAPD Markers

The genetic variability of nine Acacia nilotica subspecies of various origins was analyzed by thirty-six RAPD primers. Sixteen among them produced polymorphic bands and generated 166 polymorphic markers. The amplified bands were separated by electrophoresis on 1.8% agarose gel. The analysis of 166 RAPD markers allowed to distinguish essentially three main groups in Acacia nilotica complex: (i) The first group comprised subspecies, indica, cupressiformis, nilotica, tomentosa. Subspecies subalata and jacquemontii of which the systematic position is unclear seems to belong to this group. (ii) The second group comprised subspecies adstringens and leiocarpa. (iii) Kraussiana subspecies distinguishes itself from first two groups. The genetic variability within populations (H) was calculated through Shannon index. Subspecies adstringens presents the lowest within population variability (H= 0.015) while kraussiana and leiocarpa subspecies showed high variation index (H= 0.095) and (H= 0.096) respectively. The genetic variability analysis of Acacia nilotica revealed large differences between subspecies but no correlation between geographic distances and genetic distances could be established. Subspecies native of east Africa presented higher allelic richness than west African and Indian ones.