Genetic relationships between Sardinian and Spanish viticulture : the case of Cannonau and Garnacha

To evaluate the relationship between Sardinian and Spanish viticulture, Simple Sequence Repeat (SSR) markers were applied to define the genetic profiles of 29 cultivated and 48 wild grapevine (Vitis vinifera L.) accessions. SSR data confirmed synonymy between ‘Cannonau’ and several Spanish accessions of ‘Garnacha Tinta’. SSR analysis also suggested that the ‘Garnacha’ group consisted of a heterogeneous pool of cultivars displaying different morphological and genetic traits (Link coefficient = approx. 0.5), probably caused by somatic mutation or accidental breeding events between closely-related grapevine accessions. In contrast, the ‘Vernaccia’ - ‘Granaccia’ Sardinian group was different from ‘Cannonau’ (Link coefficient = 0.8) and all Spanish ‘Garnacha Tinta’ and ‘Blanca’ accessions analysed. To understand the ‘Cannonau’ - ‘Garnacha’ relationship, we studied the origin of these accessions and their relationships with spontaneous wild grapevine. Both cultivars are ancient grapes that have been cultivated for many centuries in both Sardinia and Spain. Although the name ‘Garnacha’ may derive from the Italian word ‘Vernaccia’, molecular analysis excluded any direct genetic origin of the Spanish ‘Garnacha’, or Sardinian ‘Cannonau’ from the ‘Vernaccia’ - ‘Granaccia’ Sardinian group. Structure analysis split the samples analysed into three clusters (K = 3). The first two clusters corresponded to the cultivated samples, while the wild accessions were in the third cluster. Based on this information, we can exclude any direct origin of the ‘Cannonau’ - ‘Garnacha’ group from the wild grapevines analysed and distributed on Sardinia.