Simple sequence repeat markers revealed genetic divergence and population structure of okra [Abelmoschus esculentus] collections of diverse geographic origin

The study was carried out to assess the genetic diversity and population structure of okra collections from diverse geographic origin using selected polymorphic simple sequence repeat (SSR) markers. Thirty-two okra accessions collected from three geographic regions were genotyped using 16 selected SSR markers. The SSR markers generated a total of 71 loci of which 67% were polymorphic. Genetic distances among accessions ranged from 2.2 to 7.1, with a mean of 4.65. Gene diversity ranged from 0.10 to 0.78 with a mean of 0.52. Genetic clustering classified the accessions into three major clusters and four sub-clusters. Each cluster and sub-cluster consisted of accessions derived from different sources. Analysis of molecular variance revealed that 67%, 81% and 83% of the total genetic variation detected was found within populations of geographic origin, altitude and collection district, respectively. The observed moderate to high population differentiation could partly be attributed to limited germplasm exchange, agro-ecological differences, and partly by selection pressure. The present study revealed the presence of high genetic diversity and population divergence among okra collections from Ethiopia. The study demonstrated that a collection strategy for conservation of okra genetic resources should focus on sampling of representative genotypes covering wide geographic regions and altitudinal ranges of target agro-ecologies.