Assessment of genetic diversity of african locust bean (parkia biglobosa jacq.) landraces using microsatellite markers

Parkia biglobosa, commonly called African locust bean, is rich in nutrition and pharmacological properties that can be explored in the food and drug industry. However, its cultivation and production is declining and genetically threatened in its natural ranges. This study determined the genetic diversity among 19 landraces of P. biglobosa collected from different agroecological areas (AEAs) in Nigeria using microsatellite markers. Genomic DNA was extracted using the modified sodium dodecyl sulfate (SDS) protocol, while amplification was performed using five primer pairs of PbL02, PbL03, PbL04, PbL05, and PbL09. Genetic diversity was analyzed using descriptive statistics and a dendrogram. The five markers were highly polymorphic, with a mean of 70.25 %. The polymorphic information content (PIC) was relatively high, ranging from 0.51 to 0.89, with a mean of 0.72. The allelic richness per locus ranged from 5 to 15, while major allele frequency ranged from 0.26 to 0.63 with a mean of 0.41. The gene diversity within a population (Hs) was quite low, with a mean of 0.28 ± 0.01, while the estimate of gene flow among the landraces was relatively high (17.50 – 2.03). The Coefficient of gene differentiation (Gst) of 0.10 indicates that about 10 % of the total genetic divergence was among populations and 90 % within the populations. The dendrogram based on the UPGMA method classified the 19 landraces into three distinct genetic clusters that shared quite some alleles and allocated landraces from different AEAs into the same cluster except cluster II. The study identified four genetically distinct landraces (Pb18, Pb16, Pb17, and Pb19) that are potentially good as parental lines for heterosis crossing. In contrast, cluster I with diverse landraces could be exploited for commercial cultivation, and conservation purposes.