Genetic diversity within Sclerocarya birrea populations in Kenya

Abstract

Knowledge on genetic diversity is important for the successful conservation and domestication of a species. In order to determine the genetic diversity within different populations of Sclerocarya birrea (A. Rich.) Hochst. (Anacardiaceae) (marula) in Kenya, leaf morphological characteristics and random amplified polymorphic DNA (RAPD) profiles from 92 and 61 trees, respectively, collected from six Kenyan stands and two reference populations from Tanzania, were investigated. Leaf blade lengths were measured, and whether leaf margins were serrated or entire was recorded. RAPD analysis was applied to genomic DNA using 10 primers of 10 base pairs each. Both leaf morphology and DNA analysis clustered the eight populations of S. birrea into three groups. Group 1 (two populations) consisted of plants with small sized leaves (average leaf blade length <3 cm) that had entire or serrated leaf margins. Group 2 (two populations) comprised plants with large sized leaves (average leaf blade length >3 cm) that, again, had entire or serrated leaf margins. Group 3 (four populations) consisted of plants with large sized leaves (average leaf blade length >3 cm) but had entire leaf margins only. RAPD analysis suggested that two Kenyan populations had particularly high genetic diversity; these two stands could be of particular conservation and genetic improvement value.