A combined approach using RAPD, ISSR and volatile analysis for the characterization of Thymus caespititius from Flores, Corvo and Graciosa islands (Azores, Portugal)

RAPDs and ISSRs were used as molecular markers and combined with the chemical analysis of the volatiles, aiming at characterizing Thymus caespititius from the islands of Corvo, Flores and Graciosa (Azores). Thirty-one individuals were analyzed using 17 RAPD and 11 ISSRs primers, which generated respectively 199 and 127 polymorphic scorable bands. Volatiles were isolated by distillation–extraction and analyzed by GC and GC–MS. Molecular data obtained from both markers discriminated assessments from Corvo and Flores which clustered separately from plants collected in Graciosa. Volatile data grouped plants in a similar way, giving rise to two groups, depending on their oil type; plants collected on Corvo and Flores yielded carvacrol-rich volatiles while those from Graciosa yielded both carvacrol and α-terpineol-rich oils.