Genetic diversity and population structure of six species of Capparis in Tunisia using AFLP markers

In order to study the genetic diversity, the phylogeographic pattern and hybridization between six Tunisian Capparis species, 213 accessions of Caper were genotyped with three primer combinations of amplified fragment length polymorphism (AFLP) markers. Out of 750 fragments generated, 636 were polymorphic and 407 of them were restricted to a single species. STRUCTURE and PCoA analyses clearly separated morphologically different populations into six distinct genetic ones. The UPGMA analysis grouped the species into three main clusters: G1 grouped C. spinosa subsp. spinosa var. spinosa and C. sicula subsp. sicula; G2 grouped C. ovata subsp. ovata and C. orientalis and G3 clustered C. zoharyi and C. aegyptia. Populations from G1, G2 and G3 were mainly distributed in arid, subhumid, and semi-arid bioclimates, respectively. Additional genetic studies on Capparis could help to identify genes underlying speciation events and local adaptation to geographic areas leading to the development of breeding programs.