Modern hybrids

In Oxfordshire in the mid-1990s, on the English equivalent of our Neighbours’ Day, every year I politely sipped at the ‘Sauvignon’ made in the small vineyard in East Hendred where I lived. Despite being north of the famous 45^th parallel, there was nothing unusual about a vineyard in England, but at the time, introducing a Sauvignon Blanc or a Syrah was not an option. This ‘Sauvignon’ was in fact a Seyval Blanc, a hybrid French variety that is only called Sauvignon in Brazil and… East Hendred.

In 1995, there was not yet any talk of climate change and very little of organic farming, but in England (like elsewhere), the issue of selecting grape varieties was the same as it is today: choosing a variety that would be popular with consumers and would have the best chance of faring well in the terroir available.

Whether a Colombard in Gers, a Grenache Noir in Roussillon, a Verdejo in Castilla y Léon, a Malbec in Argentina or a Carménère in Chile, vines have always offered up their best fruit in the sunshine. But if it is very hot during the day, grape varieties are planted at higher altitudes to benefit from the cooler night-time temperatures.

In Morocco, for example, the vines of Meknes are more than 700 metres above sea level, allowing the plants to destress overnight. The same applies in Rueda and Toro in Spain, where vines are planted at altitudes of more than 600 m.

For vineyards that are lower down, such as Lolol in Chile or Pézenas in Languedoc, the ocean or sea is never far away to temper the climate. Once the limits of vine planting are established, the grape variety is chosen based on the growing conditions, climate factors, the date that growth begins, extreme temperatures and more. Over the decades, the wine regions of the world have turned certain grape varieties into their specialities.

However, nothing is set in stone. Changes to tastes and the climate inevitably result in changes to winegrowing habits and winemaking techniques. Agronomic hazards are also constantly evolving: the vines bud earlier, which means the potential for frost on the shoots during the spring. They flower earlier and are harvested earlier. Ripening comes to a halt when temperatures sit consistently above 35°C, and if they become extreme (like this year), the leaves take on autumnal colours in June, resulting in some of the harvest being lost.

Year after year, the amount of sugar in the grapes increases, which means dealing with higher alcohol levels in the winery (over the past thirty years they have increased by around 1° per decade), at a time when consumers are looking for less heady wines. Should we just suffer on? Adapt and change by running roughshod over tradition?

Climatic events prompt a response in the vines, and for around a decade now, although winegrowers are adapting increasingly well to the consequences of capricious weather, they can still be heard talking about ‘resistant grape varieties’, ‘new grape varieties’, ‘hybrids’ and more. To be clear: grape varieties resistant to high winds during flowering and to scorching summers do not exist and are not the subject of any in-depth research. However, fast-ripening grapes resistant to drought (limiting irrigation requirements) and disease (limiting treatments), i.e. those in step with a more respectful form of cultivation, are being studied in numerous countries.

This research can sometimes be worrying. Will ‘traditional’ grape varieties be replaced with hybrids? If a vine does not adapt to areas where it has grown for millennia in some cases, will it disappear – for example, leaving the Mediterranean region and moving further north en masse?

The debate about the best winegrowing policy is ongoing, but so that it is not reduced to a standoff between progressive and conservative factions, it is important to remember that hybridisation of grape varieties is nothing new.

From a biological perspective, all species belonging to the same genus are infertile. They therefore naturally form hybrids when they come into contact with each other. For thousands of years, natural barriers have prompted the specialisation of genetic material. When isolated, these species adapted entirely to their environments. Spontaneous hybridisation has always been rife even within a single continent, but since humans have begun moving and trading beyond natural barriers, new species have had little time to adapt.

When they emigrated to America in the 16^th century with vine cuttings in their luggage, European colonists were unknowingly creating the first crosses between local and European Vitis species. Imported plants that were not well-suited to the climate and local pests ultimately withered away, but before dying they were able to flower and fertilise local species. The Atlantic was no longer a natural barrier, and some three centuries later, these American plants overcame the phylloxera crisis that began in France in 1863.

However, the importing of American plant materials did not begin with phylloxera. It first started on a large scale two decades earlier, as their agronomic properties were sometimes viewed as superior, as was their resistance to powdery mildew, a disease that had recently been imported from England. Essentially, phylloxera was introduced to Europe as part of the efforts to combat powdery mildew. But ever since humans became aware that varieties need to match up with micro or macro climates and that species (in the broader sense) need to match up with biotopes, there has been an ongoing search for the right combinations.

With this in mind, during the 1920s the Russians worked on Asian plants to improve their ability to withstand cold temperatures. At the same time, crossings with American plants achieved examples with greater resistance to downy and powdery mildew. Given this, modern hybridisation – born in the 1950s with crosses of various Vitis species that had developed their own defences in their native terroirs – was based on empirical selection methods. Used up until the end of the 20^th century, this meant that grape varieties’ resistance levels could only be characterised in terms of their phenotypic behaviour, for example in the presence of a pathogenic fungus. A long process with a return on investment only expected after twenty or twenty-five years, plant breeding was the realm of enthusiasts rather than industrialists.

The 21^st century took things further, moving from two genetic sources of resistance (Asian and American) to four. Using these sources of resistance enabled the development of what are known as polygenic varieties, in other words varieties with multiple resilience mechanisms, such as to a pathogenic fungus able to develop in ideal conditions beneath plentiful foliage. Selection aided by markers also enables us to immediately verify that the progeny have the same resistance factors identified in its parents. As the observation period is much shorter, research should progress rapidly, and between new grape varieties and/or new cultivation practices, winegrowers should in any case be able to make decisions that inspire consumer loyalty.