Genetic diversity and population structure of Eplingiella species (Lamiaceae) using ISSR markers

The present study evaluated the population structure and genetic diversity using inter simple sequence repeat (ISSR) markers in 18 natural populations belonging to three species of Eplingiella (E. cuniloides, E. fruticosa and E. brightoniae), found growing naturally in the semiarid region of Northeast Brazil. Samples of 265 plants were analyzed using nine primer combinations, which generated 131 informative bands. Eplingiella spp. populations showed moderate genetic diversity (percentage of polymorphic bands, PPB = 75.6–96.9%, Nei's genetic diversity He = 0.31–0.39, Shannon's information index I = 0.33–0.48). Molecular variance analysis revealed that within populations, variations contributed more (74%) to the genetic diversity than between population variations (26%), with percentage of the genetic differentiation coefficient (GST = 0.29). The mean value of FST was 0.175, demonstrating good differentiation between populations. The analysis of the structure by the Bayesian method revealed the formation of two groups (K = 2), with many migrant individuals and a high level of miscegenation. The hierarchical cluster dendrogram grouped the 18 populations into two major clusters, with good support for the main clades (100%). According to principal component analysis, the two main principal components explained 21.06% of the total variation. The ISSR markers used were effective in identifying the variability of natural populations of Eplingiella spp., and population structure demonstrated recent diversification of species. The results shed more light on the genetic variation and evolutionary dynamics of Eplingiella, helping to formulate effective breeding strategies.