Morphological, chemical, and genetic diversity of wild myrtle(Myrtus communis L.) populations in Sicily

Abstract

Myrtus communis L. is a shrub widespread in the Mediterranean area. The interest in this species is growing, mainly due to its pharmacological and aromatic properties. The overexploitation of wild populations induced increasing degradation of plant cover with serious risk of loss of genetic diversity. This research explored the morphological, chemical, and genetic diversity of wild myrtle populations in Sicily, with the aim to provide a first characterization of a core collection of 36 accessions from 7 localities for future domestication programs. Amplified fragment length polymorphism fingerprinting generated 152 polymorphic fragments. STRUCTURE analysis identified three genetic clusters (A, B, and C) corresponding to specific geographical origin. Analysis of molecular variance estimated a quite high overall fixation index (F ST = 0.332). Misilmeri and Ispica were the more divergent populations (F ST = 0.502), while M. Pellegrino and Scopello revealed the lowest F ST (0.153). The relationships between genetic, morphological, and biometric data were investigated. Significant correlation between genetic clusters and bush shape/plant growth behavior was found (P < 0.005). Moreover, morphological traits such as leaf, fruit, and seed size were significantly correlated to Clusters B and C. Leaves' secondary metabolite profiles were evaluated based on antioxidant activity and total tannin and phenol concentrations. High antioxidant activity differences were recorded using DPPH (21.4-35.5 mmol Trolox/100 g DW) and ABTS (24.2-39.5 mmol Trolox/100 g DW) methods. A low variability was observed among populations regarding phenol (2466-3800 mg catechin equivalents/100 g DW) and total tannin contents (93.9-262.3 mg catechin equivalents/100 g DW). Results indicated that multiple approaches based on genetic, morphological, and chemical traits might allow the characterization of natural myrtle diversity.

Genetic diversity and population structure of wild Sardinian Myrtle (Myrtus communis L.) genotypes from different microclimatic areas

“…(Table 2). Overall the average FST is 0.130 indicating a lower level of divergence compared to other myrtle populations in Mediterranean area such us Sicily (Melito et al, 2016) and Tunisia (Messaoud et al, 2006). These differences might be related to the specific localization of the sampling sites.…”

“…Several studies conducted on Italian myrtle populations have shown that molecular markers can be successfully used to characterize natural populations (Agrimonti et al, 2007;Bruna et al, 2007;Melito et al, 2013a;Melito et al, 2016). More recently, AFLP analysis has been performed to characterize domesticated (Melito et al, 2014) and wild myrtle populations (Melito et al, 2016), respectively, in Sardinia and Sicily.…”

“…More recently, AFLP analysis has been performed to characterize domesticated (Melito et al, 2014) and wild myrtle populations (Melito et al, 2016), respectively, in Sardinia and Sicily. Natural populations of myrtle are subjected to ecological risk.…”

“…These differences might be related to the specific localization of the sampling sites. In the first case, Melito et al (2016) explored the divergence of a reduced number of populations mainly from the coast area of Sicily. In the second case, the aim of the research was to study the genetic diversity of M. communis samples from upper-semiarid and sub-humid bioclimatic regions in Tunisia.…”

“…Previous studies on Italian (Melito et al, 2016;Agrimonti et al, 2007;Melito et al, 2013a;Melito et al, 2014) and Mediterranean myrtle populations (Bruna et al, 2007;Nora et al, 2015;Messaud et al, 2011;Serce et al, 2008;Albaladejo et al, 2009) showed that dominant and codominant molecular markers could associate genotype to a specific geographic area. In particular, AFLPs are extremely useful to assess the genetic diversity of myrtle, screening a large number of loci simultaneously without any preliminary knowledge on the genotype sequence.…”