A Field Collection of Indigenous Grapevines as a Valuable Repository for Applied Research

Abstract

The grapevine is an economically important plant, with a historical connection to the development of human culture. Currently, over 6000 accessions are known as individual grapevine varieties, some of which are important to national heritage, valuable for current viticultural practices, and as genetic resources to maintain plasticity under changing climatic conditions, environmental sustainability, and market demands. Recently, the diversity of cultivated grapevines has declined significantly, due to the increased focus of global wine industries on a few major cultivars. Moreover, due to biotic and abiotic stresses, the wild V. vinifera germplasm's genetic diversity has declined, with some varieties on the verge of extinction. Vitis germplasm conservation can be achieved via either in situ (e.g., protected areas) or Ex situ (e.g., field collections, seed banks, and tissue culture collections) methods. This study aims to highlight the importance of Vitis field bank collections. We demonstrate the research done in the Israeli indigenous Vitis vinifera collection. The multi-layer analysis of the varieties enabled the identification of drought stress-resistant varieties, and suggested a mechanism for this resistance through noting the dramatic phenological differences in foliage development between resistant and sensitive varieties. In addition, we show a general characterization of the varieties via major grape characteristics, including bunch and berry shape, as well as their possible utilization based on their aromatic and phenolic profiles.

Keywords: Ex situ conservation; Vitis; diversity; drought stress; field germplasm; wine.

Figure 1

K-means cluster analysis and clustering of the 33 tested varieties into strategic groups. At five time points, the varieties were clustered by their physiological parameters during an extended drought stress experiment. The physiological parameters measured were carbon fixation (photosynthesis) (An), stomata conductance (g_s), and stem water potential. Group 1—stable varieties, showing improved parameters at the late stages of the experiment, marked red. Group 2—sensitive varieties that reacted dramatically to the extended drought period, marked green. Group 3—varieties with a moderate response, marked blue. Each dot represents data for a specific vine, four vines per variety, for a total of 132 vines. Circles are drawn over varieties that were selected for emphasis in the following figures (Figure 2 and Figure 3).

Figure 2

Correlations between physiological parameters during drought stress experiment. (a) Correlation between stomata conductance (g_s) and photosynthesis (An). Two varieties represent each response strategy. (b) Correlation between stomata conductance (g_s) and stem water potential (Ψ_stem). Two varieties represent each response strategy. Each dot represents data for a specific vine at a specific time point during the drought experiment, four vines per variety.

Figure 3

Phenological observations (bud break, flowering, fruit set, and veraison) of grapevine varieties during January to July. (a) Average performance for 8 stable species and 7 sensitive species. The statistical analysis we used was the t-test. ** t < 0.01, *** t < 0.001. (b) Specific phenological sequence for 4 sensitive (green) and 4 stable (red) varieties showing the highest differences in foliage development.

Figure 4

Ampelographical observations (berry shape, berry skin color, berry length, bunch density, bunch shape, bunch length).

Figure 5

Mean monomeric and proanthocyanidin compositions of indigenous black grape varieties (n = 3 replicates per variety). mDP is the mean degree of polymerization, calculated from the sum of all subunits (flavan-3-ol monomer and phloroglucinol adduct, in nmoles, divided by the sum of all flavan-3-ol monomers, in nmoles). All other analytes are reported as mg/g berries in (+) catechin equivalents; for this visualization, mean concentrations were normalized across the observed concentration range, as shown in the figure key. For numerical data, see Supplementary Materials Table S1.

Figure 6

Mean volatile composition of white indigenous cultivars (μg/kg berries; n = 3 replicates per variety). For this visualization, mean concentrations were normalized across the observed concentration range, as shown in the figure key. For numerical data, see Supplementary Materials Table S2.