Genetic diversity and genetic structure of natural populations of Croton blanchetianus Baill. based on Inter Simple Sequence Repeat (ISSR) markers

Croton blanchetianus Baill. is an aromatic species endemic to the Caatinga (Brazilian biome), widely used in folk medicine, with proven therapeutic and biological activity. Due to its importance and potential applications, carrying out research on the species is of great significance to develop conservation and breeding strategies, as well as to contribute to definition of other potential biological activities. The aim of this study was to evaluate the genetic diversity and structure of six native populations of C. blanchetianus from different municipalities of the state of Sergipe in the Northeast region of Brazil (Aquidab & atilde;, Graccho Cardoso, Itabi, Lagarto, Tobias Barreto, and Po & ccedil;o Verde) using Inter Simple Sequence Repeat (ISSR) markers. A total of 264 polymorphic bands were detected, indicating a high level of polymorphism. Genetic variability was characterized based on the following estimates: observed mean number of alleles (Na = 1.768), effective mean number of alleles (Ne = 1.327), the Shannon Diversity Index (I = 0.332), expected heterozygosity (He = 0.208), and percentage of polymorphism (P% = 87.50). The greatest genetic variation was found within the populations (94%), the genetic differentiation among the populations was considered moderate (Phi PT\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\Phi }_{PT}$$\end{document} = 0.06 and GST = 0.05), and the gene flow, estimated by Nm statistic, was high (9.19). The estimates of genetic differentiation among the populations were determined using Nei's genetic distance and the pairwise fixation index (Phi PT\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\Phi }_{PT}$$\end{document}), showing differentiation of low to moderate magnitude. Multivariate analyses (principal coordinate analysis-PCoA, the dendrogram based on Jaccard's genetic distance and Bayesian population structure analysis) did not cluster the genotypes according to their geographic origin. These results contribute to conservation strategies of C. blanchetianus by identifying genetic variability and structure.