Genetic Diversity and Population Structure of Sardinian Myrtle (Myrtus communis L.) Selections as Obtained by AFLP Markers

Myrtle is an aromatic plant typical of the Mediterranean maquis. It is widely exploited in pharmaceutical, cosmetic, and food industries, whereas in Italy, it is mainly used for the production of the typical liqueur. Amplified fragment length polymorphism (AFLP) markers were used to evaluate the genetic variability of some Sardinian Myrtus communis L. candidate cultivars. The AFLP selective amplification produced 138 reproducible AFLP fragments, 96% of which were polymorphic. STRUCTURE analysis divided the myrtle accessions into two main genetic groups (K = 2). The two clusters showed different numbers of individuals. Most of the individuals belonged to Cluster B, whereas only eight genotypes were attributed to Cluster A. Unweighted pair group method with Arithmetic Mean (UPGMA) dendrogram segregated all the myrtle cultivars into five main groups, displaying a partial congruence with the division observed by STRUCTURE analysis. The analysis of the genetic diversity distribution in a candidate cultivar selection displayed a geographical gradient of myrtle from north to south, which reflects the Sardinian shape, and from west to east, which reflects the Sardinian mountain distribution.