The emotive issue of genetically modified vines has been thrown into sharp relief by the recent prosecution of anti-GMO protestors for vandalizing a research vineyard in Alsace in 2010. But how close are we to seeing wines produced from GM vines? And should we be concerned? Richard Hemming assesses the debate

On October 14, 2011, a French court found 63 people guilty of viticultural vandalism. Re-offenders received a two-month suspended prison sentence; first-timers were awarded fines. The guilty verdict was all but predestined, since they had actually invited the media to film them as they destroyed around 70 vines in a small vineyard in Alsace on the night of August 15, 2010.

The vines' offense was to be genetically modified, and the group of faucheurs volontaires ("volunteer reapers") who committed the crime are the self-appointed adversaries of all such experimentation. Their trial was supported by other campaigning groups with sympathetic philosophies, who traveled to the courthouse in Colmar to try to stir up some debate about what they describe as an "imminent danger" to grape growing. Genetic modification remains a controversial topic within all types of agriculture, but especially for viticulture and especially for France, with her ingrained concept of terroir as immutable and sacrosanct.

Furthermore, there is a current trend toward minimal intervention and naturalness in wine. Yet genetic modification of the vinifera grapevine could offer a solution to the diseases that plague the world's vineyards, many of which are otherwise incurable.

For instance, the vineyard targeted in Alsace belonged to France's Institut National de la Recherche Agronomique, which was researching grapevine resistance to court-noué, or the grapevine fan-leaf virus. According to Olivier Lemaire at INRA, this disease is the most devastating in French viticulture, responsible for an estimated ¤800-million annual loss to the industry. However, the protestors countered that fan leaf can be mitigated by leaving vineyards fallow for long enough before replanting and also that biodynamics can control the disease, citing Domaine de la Romanée-Conti by way of illustration. (They claim that DRC has limited fan-leaf infection to around 5 percent of its total vineyard area, a level that they allege is actually beneficial to wine quality.)

The two sides are bound to be irreconcilable. However, INRA took pains to insure that its research was as safe as possible. First, it was only the rootstock that contained transgenic material-the scions were genetically virginal. Second, the vines were prevented from ever flowering and, therefore, from producing grapes, thereby minimizing the threat of spreading any genetically modified matter into the environment. Third, the trial obeyed all the relevant laws and was overseen by a committee that included members of the public. They hoped to discover a rootstock that was resistant either to the virus itself or to the nematodes responsibly for spreading it. However, at the time of the attack, the project was incomplete and inconclusive.

The research continues

Elsewhere in the world, genetic research proceeds comparatively unhindered. At the Commonwealth Scientific and Industrial Research Organisation in Australia, they are looking into how genetic modification can influence the color, flavor, yield, and quality of grapes, as well as grapevine-disease resistance.

For example, in a 2008 paper, CSIRO scientists describe the discovery of a single gene that can confer resistance to powdery mildew. Known as RUN1, it was located in the genome of the American vine variety Muscadinia rotundifolia, which was known to be resistant to the disease. By crossing this species with a Vitis vinifera "using conventional breeding methods, [they] proved that resistance could be transferred between species."

Such crosses, however, invariably produce inferior-quality fruit-as witness mongrel varieties Huxelrebe and Rondo, for instance. So, the next step was to introduce RUN1 into premium varieties via genetic modification.

In October 2011, they announced this had been successfully achieved for various different vinifera varieties, including Shiraz. However, the researchers at CSIRO haven't been able to plant their new varieties out in the field, apparently because of wineindustry reluctance to embrace genetic modification. That reluctance is blamed squarely on the European market, a vital customer for Australian wine exports, for being suspicious of all things transgenic. That isn't to say that Australian domestic opinion is supportive, however. The comments posted about this new viticultural development on Australian news website abc.com.au are, for the most part, negative: "It beggars belief that CSIRO has publicly funded this project," "GM can't deliver, and our scientists must accept that and move on," "There is nothing that the GM industry has offered to benefit people," and "Stop wasting money on this sector" are just a handful of the objections raised.

Experimentations with grape color and flavor are likely to be even more controversial. While it might be argued that wine is already tinkered with in this way via the addition of colorants such as Mega Purple or the usage of aromatic yeasts, the genetic manipulation of the grapes for cosmetic or olfactory purposes sits uncomfortably because it runs counter to most people's perceptions of wine as a natural product.

Acid test

An interesting challenge to this perception concerns acidification. Commonplace in warm- and hotclimate vinification, the addition of tartaric acid to wine is a long-established practice. While it has often been cited as a shortcoming for those wines where overadjusted acidity sticks out, when handled in a careful manner, acidification is acknowledged as being potentially beneficial to a wine. However, tartaric acid can be costly, and judging the correct level of addition during vinification can be tricky. Far better to pick the grape with the optimal balance of sugar and acidity- and this is where genetics comes in.

In 2006, the discovery of an enzyme responsible for the synthesis of tartaric acid in grapes was described in a paper by DeBolt et al. Modifying the appropriate gene in a grapevine would therefore allow grapes to increase their content of tartaric acid. Assuming this could be done safely and without detriment to other aspects of wine quality, there is a persuasive argument that genetic modification of this sort is better for wine than acid addition.

Conjecture aside, Dr Jamie Goode, an eminent writer on the science of wine, points out that "the biggest objection is the fact that the diversity of wine would be threatened as an unintended consequence of the introduction of GM vines. Their production and field testing would be very expensive, so people would only do it with a few varieties-the most popular. This would squeeze out minor varieties. I think that the end result would be a loss of diversity, which might be a bigger cost than the benefits GM vines would bring."

On the other hand, Stephen Skelton MW emphasizes the commercial reality, saying in his book Viticulture: "If GM vines can be produced that require no spraying and can be properly tested so that their safety to both the environment and the consumer is guaranteed [...], then it is likely that their introduction will eventually happen."

He cites the success of genetically modified soya, rice, and cotton as evidence of the compelling commercial advantages of transgenic crops. Indeed, genetically modified yeast has been in use for vinification for some time. For example, ML01 is a transgenic strain of yeast produced by Springer Oenologie; it offers simultaneous alcoholic and malolactic fermentation, as well as lower volatile acidity and greater color intensity. According to InnovationCanada.ca, the scientist who originally developed the yeast also claims that it "eliminates the molecules that cause headaches."

ML01 was classified as "generally recognized as safe" by the US authorities in 2003 and permitted for use in wineries thereafter. An estimated 2,000kg (2.2 tons) will be used in wineries in North America in 2012, making around 100,000 liters of wine. It is also authorized for vinification in South Africa-but the vast majority of winemaking countries have not approved its usage.

Research into genetic modification continues apace, then, but it seems overall unlikely that the word "transgenic" is destined to appear on wine labels any time soon.

Back in Alsace, the INRA center is still licensed to carry out experiments with genetically modified material. It was awarded €57,000 from the court case-but that was only enough to cover the legal costs, so at present INRA hasn't restarted its field research. When it does, it hopes it will be able to produce a fan-leaf-resistant rootstock within ten years-a task in which it will fail if the faucheurs volontaires have anything to do with it.