Aroma quality of fruits of wild and cultivated strawberry (Fragaria spp.) in relation to the flavour-related gene expression.

The expression profiles of flavour-related genes and aroma quality of fruit headspace were investigated in the four strawberry genotypes “Regina delle Valli” (Fragaria vesca), “Profumata di Tortona” (F. moschata), “Onda” and VR 177 selection (F. x ananassa). Real-time RT-PCR analysis was used to identify Nerolidol Synthases (FaNES1 and FaNES2) and Monoterpene Synthase (FvPINS) genes in F. x ananassa and F.vesca, respectively. In F. x ananassa genotypes the terpenoid profile was characterized by nerolidol, whereas wild species produced mainly monoterpenes. The flavour biogenesis in ripening fruit was largely determined by the expression of a strawberry alcohol acyltransferase (SAAT) gene, especially in “Profumata di Tortona” and “Regina delle Valli”. The fruit solid-phase microextraction (SPME) headspace was analyzed using the Gaschromatography-Olfactometry (GC-O), that allows the chromatographic separation of volatiles together with their olfactometric evaluation. The aroma quality differed among the genotypes: “Regina delle Valli” had a peculiar profile characterized by high concentrations of limonene, linalool and mesifurane that resulted in “spiced”, “citrus, floral” and “sweet, baked” descriptors; the character impact compound in “Profumata di Tortona” was ethyl butanoate, responsible for “sweet” and “fruity, strawberry” descriptors, which, however, was developed in lower amount if compared to the F.x ananassa genotypes. The sesquiterpene nerolidol was identified in both cultivated strawberry genotypes.