Eastern origin and three-millennia persistence of a founding grapevine lineage in Iberian viticulture

Viticulture became central to most Mediterranean civilizations a few millennia after the grapevine (Vitis vinifera L.) was domesticated in the South Caucasus/Near East. To elucidate the origins of the grapevines that enabled this westward spread over the past 3,000 years, we analyzed 28 grapevine seeds from seven archaeological sites in the Iberian Peninsula and Sardinia. Ancient DNA recovered from the oldest seeds with domesticated-like morphology (from ∼1,000 BCE), found in southwestern Spain, revealed nuclear and chloroplast genome signatures of Eastern Mediterranean cultivars. Seeds from the same and later Iron Age Iberian sites, however, showed genomic signatures suggesting hybridization between local wild grapevines and eastern-origin cultivars. The genetic makeup of Sardinian and northeastern Spanish seeds supports that local diversification giving rise to the Central European and Iberian wine genetic lineages had already occurred in the early Iron Age. In Iberia, Roman-period seeds were first-degree related to both the earliest eastern-introduced domesticates and a Medieval seed whose genetic makeup matches the extant Iberian variety "Pasa Valenciana." Another Medieval seed was inferred as an offspring of the extant "Heben," indicating that this major founder of Iberian germplasm has been continuously propagated for over 1,100 years. Our results confirm previous evolutionary models indicating that Western Mediterranean viticulture began with introductions of eastern domesticated grapevines, followed by early hybridization with local Iberian wild grapevines that may have facilitated viticulture adaptation to the new environment. The aDNA unveils that these introductions gave rise to extant cultivars through only a few sexual generations and long-term reliance on clonal propagation.