Rară Neagră 2.0: prospecting, improving and safeguarding the biodiversity in an eastern european heritage grape variety

The Rară Neagră 2.0 project aims to restore and safeguard the intra-varietal diversity of the ancient Eastern European grape variety Rară Neagră through polyclonal selection and the establishment of a certified genetic conservatory. A total of 159 accessions were collected from 30 old vineyard plots in Romania, the Republic of Moldova, and Ukraine, representing plantings aged from 25 to over 100 years. Morphological characterization was carried out in 2024 based on eight key traits related to vine vigour, productivity, bunch and berry structure, and epidermal features. Statistical analyses (PCA, hierarchical clustering, Wilcoxon rank-sum tests) revealed significant intra-varietal variability, allowing the identification of two stable morphological groups with differentiated agronomic and oenological potential. Sanitary testing was performed using the ELISA method on dormant cane samples. Approximately 16.4% of accessions tested positive for one or more major grapevine viruses, mainly GLRaV-1 and GLRaV-3, while only one accession showed the presence of ArMV/GFLV and none were infected with TBRV. All virus-positive vines were excluded from the final selection. The results support the implementation of a polyclonal selection strategy based on both phenotypic diversity and sanitary integrity. The selected 133 accessions will form the foundation for a high-quality mother vineyard, contributing to genetic conservation, sustainable viticulture, and the long-term valorization of this emblematic local variety. Additionally, the identification of a stable parthenocarpic seedless mutant and several atypical pigmentation biotypes provides new insights into the genetic complexity of Rară Neagră and highlights the importance of conserving its full phenotypic spectrum.