Evolution and history of grapevine (Vitis vinifera) under domestication: new morphometric perspectives to understand seed domestication syndrome and reveal origins of ancient European cultivars

Abstract

Background and aims: In spite of the abundance of archaeological, bio-archaeological, historical and genetic data, the origins, historical biogeography, identity of ancient grapevine cultivars and mechanisms of domestication are still largely unknown. Here, analysis of variation in seed morphology aims to provide accurate criteria for the discrimination between wild grapes and modern cultivars and to understand changes in functional traits in relation to the domestication process. This approach is also used to quantify the phenotypic diversity in the wild and cultivated compartments and to provide a starting point for comparing well-preserved archaeological material, in order to elucidate the history of grapevine varieties.

Methods: Geometrical analysis (elliptic Fourier transform method) was applied to grapevine seed outlines from modern wild individuals, cultivars and well-preserved archaeological material from southern France, dating back to the first to second centuries.

Key results and conclusions: Significant relationships between seed shape and taxonomic status, geographical origin (country or region) of accessions and parentage of varieties are highlighted, as previously noted based on genetic approaches. The combination of the analysis of modern reference material and well-preserved archaeological seeds provides original data about the history of ancient cultivated forms, some of them morphologically close to the current 'Clairette' and 'Mondeuse blanche' cultivars. Archaeobiological records seem to confirm the complexity of human contact, exchanges and migrations which spread grapevine cultivation in Europe and in Mediterranean areas, and argue in favour of the existence of local domestication in the Languedoc (southern France) region during Antiquity.

Fig. 1.

Geographical location of wild, cultivated and archaeological material collected for this study.

Fig. 2.

Assessment of the number of harmonics needed for an optimal description of seed outlines based on the analysis of three seeds of the ‘Gamay’ cultivar. (A) Average distance (deviation) between reconstructed and optimal outlines in relation to the number of harmonics considered. (B) Measurement errors on harmonics, from H1 to H32, evaluated based on the coefficient of variation of the same seed photographed ten times. (C) Seed outline reconstructed by addition of successive harmonics (optimal description of seed outline is reached by H32).

Fig. 3.

Canonical variate analysis biplot 1–2 (37·9 % of the total variance) showing that wild grape accessions and cultivated varieties are discriminated according to the EFT method. For additional clarity, photographs of distinctive seeds and centroid of groups are represented.

Fig. 4.

UPGMA dendrogram based on the minimum Mahalanobis distance among wild grape populations and cultivars. Discriminant rate (%) and reconstructed seed outlines in dorsal and lateral view of morphoclades identified are also presented.

Fig. 5.

Geographical structure of morphological diversity related to the distribution of French vineyards (shaded).

Fig. 6.

Photographs of archaeological seeds allocated to modern grapevine forms.