Analisi della variabilità genetica in popolazioni siciliane di Myrtus communistramite marcatori AFLP

Abstract.Myrtus communisL., a shrub widespread throughout the Mediterranean region and the Middle East, is grown in different regions for its aromatic properties and ornamental value. In past years wild germplasm of myrtle from different Italian regions was collected at the CRA-FSO (Sanremo, Italy) with the aim to characterise variability in morphological traits and to select new plant material for ornamental use. In particular, twelve populations from Sicily, showing large variability concerning leaf arrangement, were analysed. AFLP (Amplified Fragment Length Polymorphism) markers were used to evaluate the genetic variability among myrtle wild genotypes collected from different locations. Ninety-seven individuals were analysed with four selected combinations of primers. A total of 105 polymorphic bands were scored and used for the analysis of genetic distances. Pairwise similarities were computed using Simple Matching coefficient and the arising similarity matrix was used to construct a phylogenetic tree by means of the Unweighted Pair Group Method with Arithmetic Average (UPGMA). The resulting dendrogram did not show a perfect grouping of genotypes according to their particular population, except for 6 populations in which individuals grouped in specific clusters. Analysis of Molecular Variance (AMOVA) revealed that the variability within populations represented the greatest source of variation (73%). Therefore, the high intrapopulation variability recognized could explain the presence of some ungrouped genotypes in the cluster analysis. Furthermore this situation might be imputed to the action of birds, feeding on myrtle berries, which contribute to the wide dispersal of seeds, thus allowing gene flow among populations of different areas. A greater understanding of the distribution of the variability could then result from the comparison with the migration routes of birds.