Genetic structure and molecular divergence among samples of mandacaru (Cereus spp.; Cactaceae) as revealed by microsatellite markers

Abstract

Microsatellite transferability was used as a method to differentiate samples of mandacaru cultivated in the South (S), Southeast (SE), Northeast (NE) and Midwest (MW) regions of Brazil. Ten microsatellite primers designed from Polaskia chichipe (Pchi5, Pchi21, Pchi44 and Pchi47), Ariocarpus bravoanus (mAbR05, mAbR28 and mAbR86), Astrophytum asterias (AaB6 and AaD9), and Echinocactus grusonii (mEgR78) were polymorphic. A total of 31 alleles, which makes an average of 2.58 alleles per locus, were detected in mandacaru plants. The analyzed mandacaru cacti from the NE region presented lower polymorphism than their relatives from S, SE, and MW regions. The AMOVA showed a higher genetic variation among than within the analyzed samples. Clustering of the samples determined via Bayesian analysis indicated that the 112 analyzed mandacaru plants were grouped into 3 subpopulations. The highest proportion of plants from the S/SE (80.3%/77.5%), NE (91.5%), and MW (95%) were observed within blue, red, and green groups respectively: the mandacaru cacti form genetically structured populations. Molecular divergence at the SSR loci indicated three species: one species located in the South (S) and Southeast (SE) regions, another species in the Northeast (NE) region, and a third one in the Midwest (MW) region of Brazil.