Physicochemical and Genetic Diversity Studies of Vitellaria paradoxa in Northern Nigeria

Abstract

Shea tree is an economic plant with factors such as genetic variations and environmental conditions responsible for its variations. The present study was aimed at establishing the physicochemical properties and genetic variation of shea tree from northern Nigeria. The plant materials were harvested from Bosso (A), Ngaski (B) and Yamaltu-Deba (C). The sheanut B had the highest potassium content while sodium and magnesium were higher in C, with no significant difference between the calcium and copper contents of A and C. The percentage yield of sheabutter B (37.20%) was higher than A and C. Iodine values ranged from 22.32 ± 0.12^a mg/g to 58.67 ± 0.20^c mg/g. Sheabutter B have the highest saponification value at 198.51 ± 0.21^c mgKOH/g, with no significant difference in the peroxide values of B (0.72 ± 0.03^ameqO₂/g) and C (0.74 ± 0.03^a meqO₂/g). Stearic and oleic acid are the major fatty acids identified in the GC-MS profile of the sheabutters. The microsatellite markers used produced 71 % polymorphic and 19 % monomorphic bands with allele numbers ranging from two to four, with polymorphic information content range of 0.3092 to 0.5658 and genetic diversity ranging from 0.3378 to 0.6222. Fifteen shea tree varieties were divided into two clusters with cluster A made up of four subclusters and cluster B consisting of two subclusters. The Nei’s genetic distance within the population was between 0.00% and 0.982 %, an indication of diversity within the individual trees and not between the populations across different geographical distance.