Abstract
The Lithuanian breeder Antanas Gailiūnas (1918–2004) developed a series of interspecific grapevine hybrids suited for the northern climate. With recent climate change and milder conditions, some of these hybrids have become the main varieties cultivated in Lithuanian vineyards. However, after about 50 years of vegetative propagation by amateur growers, significant plant heterogeneity has been observed. It remains unclear whether these differences are purely phenotypic or also genotypic. Additionally, the origin of many Lithuanian grapevine seedlings is undocumented. According to EU wine regulations, only Vitis vinifera varieties or regionally registered hybrids may be used for wine production. The aim of this study was to assess the genetic diversity and potential origin of grape varieties commonly grown in Lithuania. A total of 78 grapevine leaf samples were collected from six vineyards. Molecular identification was carried out using eight microsatellite (SSR) markers, following the guidelines of the International Organisation of Vine and Wine (OIV). In total, 133 polymorphic alleles were identified, with allele numbers per primer pair ranging from 7 to 18. The most informative loci were VVMD7 and VVMD28. The SSR profiles revealed clear genetic distinctions among the genotypes and helped identify cases where different sample names shared the same genetic code. These results confirm the effectiveness of SSR markers for grapevine genotyping and provide valuable data for distinguishing, authenticating, and potentially registering local Lithuanian grape varieties in line with EU regulations.