Between Roots and Clusters: The Secret Heritage of the Vine

A few days ago, my 11-year-old son asked me to buy him a book titled “How to Explain Genetics with a Mutant Dragon.” Well, we’re not here to talk about mythological creatures, but it did inspire me to write an article about the evolution of the vine and, in particular, the origins of the almost infinite spectrum of grape varieties that exist—focusing especially on those involved in the making of cava.

The vine, that ancient plant that gives us grapes to eat, raisins to sweeten, and wines to enjoy, hides a fascinating diversity within its genetic structure. When we delight in the bubbles of a sparkling wine, we rarely think about the biological complexity behind those sensations. Yet, understanding how vine genetics works can help us see why there are so many grape varieties, why some are ideal for winemaking and others for the table, and how different species can have unique characteristics.

The Wild Lineage of an Ancient Plant

The vine belongs to the genus Vitis, which includes around 60 species. The best-known and most widely cultivated is Vitis vinifera, native to Eurasia and responsible for the vast majority of grapes used in wine and table grape production around the world. Other species, such as Vitis labrusca, Vitis riparia, Vitis aestivalis, and Vitis rotundifolia, are native to North America and are mainly used in breeding programs—as rootstocks or in regions with extreme climates.

Broadly speaking, vines can be divided into two groups:

• Different species: types of vines that have significant genetic differences and often cannot cross naturally—or, if they do, their offspring may be sterile or have undesirable traits.

• Varieties (or cultivars): subgroups within the same species—such as Vitis vinifera—that share most of their genes but display notable differences in flavor, shape, color, climate adaptation, and disease resistance, among other traits.

A Thousand Faces, One Species: The Magic of Vitis vinifera

The species Vitis vinifera is by far the most prolific in terms of varieties. It’s estimated that there are between 5,000 and 10,000 different varieties, though many are rarely cultivated or even unknown outside their place of origin. In most cava from Penedès—including Alsinac—the three main varieties used are Xarel·lo, Macabeo, and Parellada.

These varieties, like many others not mentioned here, have arisen through natural processes of mutation and selection over centuries. Unlike many plants, vines are propagated almost exclusively vegetatively (through cuttings or grafting), meaning that each plant has exactly the same genetic sequence as the original. This contrasts with sexual reproduction, in which genetic material from two individuals is combined.

However, vegetative propagation does not prevent spontaneous mutations. For example, the Pinot Noir grape has given rise to Pinot Gris and Pinot Blanc through natural mutations that affect color genes. These mutations are a key source of diversity within the same species.

Small Differences, Great Wines

Differences between varieties stem from small changes in DNA (less than 1%), which affect various aspects:

• Chemical composition: levels of sugars, acids, and phenolic compounds (such as tannins and anthocyanins).

• Morphology: grape size and shape, cluster density, skin thickness, and more.

• Ripening cycle: some varieties have short cycles and ripen early, others have long cycles.

• Winemaking or table aptitude: some are better suited for vinification due to their chemical profile, while others are preferred for direct consumption thanks to their flavor, texture, and resistance.

In recent years, thanks to genomic tools, researchers have identified genes associated with key traits such as resistance to diseases (like mildew and powdery mildew) and tolerance to water stress. This allows the development of new varieties better adapted to climate change or market demands.

Beyond vinifera: The Hidden Family of the Vine

Although Vitis vinifera dominates global viticulture, other species have played fundamental roles in the vine’s history and future:

• Vitis labrusca: native to the eastern United States, known for its distinctive “foxy” aroma. The best-known variety is Concord, widely used in juices and jellies.

• Vitis riparia: grows wild in North America and is often used as rootstock for its resistance to pests and diseases.

• Vitis rotundifolia (also known as Muscadine): has distinct genetic traits, even a different number of chromosomes, making crossbreeding difficult. It produces large, resilient grapes used in parts of the southern U.S.

• Vitis amurensis: native to eastern Asia, it is extremely cold-resistant and is being studied for its potential in regions with harsh winters.

These species, although not commonly used for winemaking, are essential in breeding programs. For example, after the phylloxera crisis in the 19th century—a devastating pest for Vitis vinifera—European vines began to be grafted onto resistant American rootstocks, a practice still in use today.

Genes with Purpose: Cultivating the Vine’s Future

Today, genetic sequencing technologies (such as CRISPR—a gene-editing system based on a natural bacterial defense mechanism against viruses) open up possibilities for creating varieties that retain the organoleptic qualities of Vitis vinifera while gaining greater disease resistance, reduced pesticide needs, or improved adaptation to specific soils and climates. However, wines derived from genetically modified vines still face legal and cultural barriers.

At the same time, genomic studies are helping to trace the lineage of ancient varieties, identify beneficial mutations, and preserve viticultural biodiversity—a heritage that is both cultural and agricultural.

Three Grapes, Three Paths: The Origin of a Glass of Cava

Although it is difficult to determine exactly when the traditional cava varieties emerged, historical and genetic evidence suggests that Xarel·lo, Macabeo, and Parellada have ancient roots. Xarel·lo probably dates back to the Middle Ages or earlier, the result of natural crossings in the Mediterranean; Macabeo, documented since the 16th century, was already widely cultivated in northeastern Iberia; and Parellada, though recognized as a distinct variety more recently, may have an even older lineage under different local names. Together, these varieties embody centuries of adaptation and selection—a living history expressed in every glass of cava.

Sources
– This, P.; Lacombe, T.; Thomas, M. R. (2006). Historical origins and genetic diversity of wine grapes. Trends in Genetics, 22(9), 511–519. A key paper explaining the origin and genetic diversity of Vitis vinifera through DNA studies.
– Martínez-Zapater, J. M.; & Eiras-Dias, J. E. (2010). Genética y mejora de la vid. In: A. Urrestarazu (ed.), Avances en Ciencias y Técnicas Agrícolas. Editorial Mundi-Prensa.
– Organisation Internationale de la Vigne et du Vin (OIV) (2021). Focus OIV – Biodiversité de la vigne.
– Schneider, A.; & Mannini, F. (2001). La selezione clonale della vite: risultati e prospettive. Rivista di Viticoltura e di Enologia, 54(4), 17–28.
– Galet, P. (2000). Dictionnaire encyclopédique des cépages. Hachette. A monumental work compiling ampelographic information on thousands of varieties.
– Laucou, V. et al. (2018). Extended diversity analysis of cultivated grapevine (Vitis vinifera L.) reveals high levels of diversity, structure and gene flow within the species. PLoS ONE, 13(2): e0192540.
– Government of Spain – Ministry of Agriculture, Fisheries and Food (2020). Variedades de vid autorizadas en España.
Available at: https://www.mapa.gob.es. Official document with descriptions, authorizations, and distribution of grape varieties in Spain.