Two main distinct evolutionary stories describe the Italian grapevine assortment

Abstract

A dataset of high-quality 7k SNP profiles of 1,038 unique Eurasian grapevine varieties was used to infer the most likely grapevine migration events, a spatial ancestry estimation, and a model about the origin of Eurasian grapevine germplasm. The comparison of putative gene flow scenarios from Caucasus throughout Europe aided to fit the more reliable spreading routes around the Mediterranean Basin. The same dataset was also used to assess the population genetic diversity, structure, and relatedness of Italian varieties. These data suggested a different history between Northern and Southern Italian grapevines, appearing clearly split into two different clusters. Interestingly, the Italian genotypes were shown to be distinguishable from all the other Eurasian populations for the first time. The same SNP panel was used to determine parental relationships, identifying the main parents of traditional Italian and closely related cultivars. The parentage network suggested that Italian germplasm largely originated from a few key parents distributed into several geographical areas of genetic influence, with more or less large overlaps. These key cultivars are ‘Bombino bianco’, ‘Garganega’/‘Grecanico’, ‘Mantonico bianco’, ‘Orsolina’/‘Coccalona nera’, ‘Muscat à petits grains blanc’, ‘Malvasia odorosissima’, ‘Sangiovese’, ‘Sciaccarello’, ‘Visparola’ and ‘Vulpea’. The pedigree reconstruction by fullsib and second-degree relationships highlighted the pivotal role of some cultivars, such as ‘Visparola’, until now scarcely known. A hypothetic migration of this variety from Southern to Northern Italy along the Eastern side, as well as ‘Sangiovese’ migration from Southern to Central Italy along the Western side might be supposed. Moreover, ‘Muscat à petits grains blanc’, mainly through its offspring ‘Malvasia odorosissima’, furnished a consistent contribution to the development of many aromatic grapes grown in the Northern-Western part of the Italian Peninsula. These results represent the most complete study of grapevine Italian population genetics that has been carried out until now on the Italian germplasm.