In the 19th century, a microscopic pest almost brought the entire French wine industry to a halt. Phylloxera, a tiny louse that feeds on plant roots, made its way from North America to France in the 1850s, spreading from one vineyard to another until it had infected the whole country. What became known as the Great Wine Blight killed 915,000 acres of vineyards, damaged 620,000 acres, and cost the French economy 10 billion francs (almost $108 billion today).

In 1870, a solution emerged—though French vintners weren't happy with it. Charles Valentine Riley, an entomologist from Missouri, showed that by grafting phylloxera-resistant American rootstocks onto European grape vines, the disease could successfully be prevented from spreading. But European cultivators felt that grafting would destroy the purity of the wines, impacting their taste and flavor.

Winemaking is an industry steeped in tradition. While enthusiasts typically consider this a good thing, the phylloxera crisis is a historic example of how its inability to adapt almost led to the industry’s complete collapse. Long-standing ideals for wine purity and taste persist today, leaving vineyards vulnerable to new pests—but now, some scientists are applying 21st-century gene-editing techniques to this old problem.

Wine's Ancient Origins, Today

According to a study conducted in 2011 by the U.S. Department of Agriculture, wine grapes were first domesticated around 8000 years ago. Since then, the 10 or so most popular grape variants have undergone little to no evolution.

Evolution occurs in the form of change to an organism’s DNA. The change is a result of genetic mutations and interbreeding that occur over several thousand years. While most cultivable crops, like wheat for example, have undergone countless evolutionary changes since being first domesticated in the earliest years of human history, the most popular wine grapes have remained mostly the same from a genetic perspective.

“There are 20,000 varieties listed in the Vitis International Variety Catalogue, so there is a lot of genetic diversity,” Timothy Martinson, a viticulture specialist for the Cornell College of Agriculture and Life Sciences, tells Mental Floss. But, he adds, European wine grape variants such as Pinot Noir, Chardonnay, Sauvignon Blanc, Cabernet Franc, and Cabernet Sauvignon are all descendants of the same species, Vitis vinifera. They are also very closely related to each other genetically. This makes them susceptible to a long list of pathogens, especially those originating in North America.

The Problem with Hybrids

Pinot noir grapes are among the least genetically diverse.photohomepage/iStock via Getty Images

The easiest solution to this problem is to add disease resistance to these varieties by crossbreeding with more resistant varieties from America, but even that presents its own challenges. “Grape breeding is much more time-consuming and expensive than breeding annual crops like corn or wheat,” Martinson explains. “From seed to mature vine takes three years, and a lot more field space and care than an annual crop.”

Moreover, European cultivators haven’t generally been amenable to the idea of interbreeding, and there is a reason behind that too. In the 1870s, before grafting took root as the primary solution to the phylloxera crisis, a lot of winemakers had already started crossing European vines with North American ones. The efforts worked, and eventually, France had a little less than a million acres of land dedicated to these hybrid wine grapes.

But there was a problem. In the absence of advanced technology, grape breeders were forced to rely on an expensive trial-and-error method that yielded poor-quality produce. The cultivators soon realized that the hybrid wines weren’t nearly as good as the purebred ones. Eventually, the French government introduced legislation to strategically discourage the cultivation of hybrid wines and winemakers went back to growing only purebred varieties through grafting. Since then, French-American hybrids have been looked down upon by vintners and wine enthusiasts alike.

Because the crops took so long to mature, it was already too late by the time they realized the wines were below par. That all changes with genetic sequencing.

Sequencing For Success

By taking out a small leaf sample from any grape vine, plant biologists can now figure out the exact sequence of genes contained within its cells’ DNA, which allows them to develop genetic maps and chart out the various pathways for breeding.

“Before inexpensive DNA sequencing,” Martinson says, “breeders were basically using trial and error ... now with DNA markers, breeders can test seedlings and discard the ones that don’t have the appropriate DNA markers early in the process. This makes selection more efficient and fills the ‘pipeline’ with better material.”

Martinson is part of the VitisGen Project, a collaborative initiative aimed at developing better quality wine through genetic sequencing and breeding. The project’s current focus is disease resistance, especially resistance to a widespread fungal disease called powdery mildew. The idea is to reduce the need for pesticides by helping the vines develop an internal resistance to the fungi.

Martinson and his colleagues accomplish this by identifying new genetic markers—DNA snippets that can be linked to specific characteristics, such as resistance to a certain disease—within the plant’s cells.

The progress has been good, but there is one hurdle—wine fans may not be familiar with the new varietal names. When two different wine types are interbred, the resulting plant needs to be called something different. “Consumers want Chardonnay and Cabernet Sauvignon—and new varieties, regardless of how high quality the resulting wines are, will be named something different," Martinson says. For example, UC Davis has released five new varieties, including a red named paseante noir. "Even if it is widely planted and marketed, it will be a long time before consumers go to a wine store and ask for it by name."

Cutting-Edge Wine with CRISPR

Old wines are getting a genetic facelift.porpeller/iStock via Getty Images

There’s a possible solution to that problem, too—gene-editing. The process has been described as a find-and-replace feature similar to that in word-processing software. CRISPR, the most promising gene-editing technology currently available, involves injecting an organism, be it a human or a grapevine, with a chemical containing millions of tiny particles. Each particle consists of a guide molecule to point it in the right direction, an enzyme to edit and remove the target DNA, and a snippet of healthy DNA to replace the DNA that was just removed. 

Introducing a new gene into an existing grape merely changes its traits while the variety of wine remains the same. This process can greatly assist marketing efforts in an industry where sales are mainly dependent on variety, even more so than quality. Given the industry’s devotion to tradition, it can also make the idea of genetic modification an easier sell to vintners and cultivators.

Gene editing technology has already shown a lot of promise in a number of isolated studies involving wine grapes. In the most recent example, Rutgers University researchers successfully used the CRISPR/Cas9 technique in 2019 to develop downy mildew resistance in Chardonnay. They isolated three genes that invite downy mildew outbreaks in wine grapes and successfully edited them to create a disease-resistant version of the crop.

Earlier efforts have also borne fruit. In 2015, researchers from the University of Illinois at Urbana-Champaign used CRISPR/Cas9 to genetically modify the yeast used to ferment wine. By doing so, they increased the amount of resveratrol, a component found in wine, that was produced during the fermentation process. The wine didn’t even cause a hangover.

The wine industry's interest in breeding techniques and gene editing stems from its over-reliance on pesticides, which has become a safety concern for consumers. Martinson has written about a case in Bordeaux from 2014 in which 23 students became seriously ill after inhaling pesticides being sprayed in a nearby vineyard.

Since then, governments have progressively loosened legislation to encourage vintners to look for more innovative methods to curb disease resistance instead of relying on pesticides. Martinson says he’s optimistic: The general attitude towards genetic modification seems to be opening up, and people are finally catching on to the consequences of a winemaking tradition so frozen in time.