Genetic diversity and structure in natural populations of Maytenus truncata Reiss, 1861, a medicinal plant vulnerable to extractivism in Bahia State, Brazil

Maytenus truncata (Celastraceae) is a plant species widely used in the treatment of ulcers and tumors. Despite the intensive harvest of native specimens in the State of Bahia, northeastern Brazil, there is no information about the genetic variability or structure of this species. Therefore, the goal of this study was to estimate the genetic diversity and population structure of M. truncata based on inter simple sequence repeat (ISSR) molecular markers. The samples comprised specimens from Jequié, Contendas do Sincorá, Boa Nova, and Boa Vista do Tupim in the State of Bahia. After selection of eight ISSR primers, the percentage of polymorphic loci was equal to 96.2% and genetic diversity was 0.3581. The Mantel test revealed positive correlation among genetic and geographic distances (r = 0.5462), but it was not significant (r ≥ 0, P = 0.8365). Even though AMOVA revealed that most variation was found within populations (68%), a high structuring was detected among them (ΦST = 0.31, P < 0.001). Both UPGMA and Bayesian analyses indicated that gene flow was higher between Jequié and Contendas do Sincorá, whereas samples from Boa Nova and Boa Vista do Tupim were more isolated. This result is likely because of the population decrease and restriction to gene flow associated with intensive extractivism of populations of this species.