Symmetry Analysis in Vitis vinifera L. Seeds Reveals Differences Between and Within Cultivars

Seeds of Vitis vinifera L. exhibit a distinct bilateral symmetry, a geometric property widely used in biological systems to assess developmental stability and morphological organization. When properly oriented, seed outlines can be divided into two corresponding halves along their longitudinal axis, enabling quantitative assessment of symmetry. This characteristic offers a framework for the characterization and classification of grapevine cultivars and clones. In this study, we developed an automated computational workflow to quantify bilateral symmetry in grapevine seeds. Seed outlines were first modelled using Elliptic Fourier Analysis (EFA). Geometric symmetry was subsequently evaluated in R using Generalized Procrustes Analysis (GPA), yielding a scale-independent Symmetry Index (SI). The methodology was applied to a collection comprising 62 Vitis vinifera cultivars and three wild non-Vitis vinifera species. The Symmetry Index showed significant negative correlations with both seed area and mean contour curvature. Wild species (Group I) exhibited significantly higher symmetry values than domesticated groups. Among cultivated grapevines, the Muscat lineage (Group IV) displayed the lowest symmetry values and the greatest morphological dispersion. Differences in SI were detected not only among cultivars but also among clonal or regional expressions of the same variety cultivated under distinct geographical conditions. Symmetry analysis provides a robust, non-destructive, and high-resolution tool for the characterization of Vitis germplasm. By integrating geometric morphometrics and automated shape analysis, this approach offers new opportunities for cultivar discrimination, evolutionary studies, and the quantitative assessment of morphological diversity in grapevine seeds.