Why GMO Wine Grapes Would Be Cool

 

Chardonnay grown in Colorado

I am 99.9% sure that there will never be commercial production of genetically engineered wine grapes ("GMO" to use the common misnomer).  Even so, I'd like to indulge in imagining what could be if we lived in some parallel universe where rational scientific thinking prevailed.

Wine grapes are an extremely logical crop for genetic engineering because there is no tolerance for changing varieties. For annual crops like grains or vegetables, new varieties are bred on a regular basis to solve pest issues or to improve features like taste or shelf life. Breeding of perennial fruit crops is a much, much slower process, but entirely new varieties are still introduced from time to time (e.g. Jazz or Pink Lady apples).  Even what we call "heirloom varieties" of most vegetable or fruit crops are mostly quite young by wine grape standards.

Conventional breeding just isn't a viable option for wine grapes, not because it couldn't be done, but because in an industry so focused on quality and tradition, no one would consider it. The wine industry is based on specific varieties which are hundreds of years old and for which no new variety would ever be acceptable. That is true for varieties in their original appellations (e.g. Pinot Noir and Chardonnay in Burgundy or Cabernet Sauvignon and its blending partners in Bordeaux).  It is also true for those same varieties that now make great wines in "New World" (e.g. Malbec in Argentina, Zinfandel in California, or Syrah in Australia).

Therefore, wine grape varieties have been cloned for hundreds of years, specifically to avoid any genetic change (they have always been grown from rooted cuttings or from grafted buds). Grapes make seeds, but the seed won't grow up to be the same variety as the parent, thus they are never used as a way to grow new vines.

The Downside of Ancient Varieties

Of course, by sticking to very old varieties, wine grape growers must deal with many problems which might otherwise have been solved through breeding.  Grape growers have been able to deal with some pests that attack the roots by grafting onto diverse "root stocks" with novel genetics.  That was the solution to the great Phylloxera epidemic of the 19th century. But rootstocks can only help with a limited number of grape growing challenges.

Why Genetic Engineering Would Be Logical For Grapes

Biotechnology is a perfect solution for wine grape issues because it allows changes to address one specific problem without disrupting any of the characteristics that determine quality. Of course, each variety would have to be individually transformed, but in our imaginary rational universe the regulatory regime would be made easier for multiple uses of the same basic genetic construct.

So, genetic engineering could be a very cool solution for various challenges for grapes.  I'll list a few of the diseases that might be fixable this way.

Mildews

Grape Downy Mildew infection on a leaf

As I described in an earlier post, the noble grapes of Europe must now be rather intensively sprayed with fungicides because a disease called Downy Mildew was introduced in the mid-1800s from New World grape species. Those same North American species have a good deal of resistance to that disease, and the genes for those traits could probably be identified and moved into the traditional, high-quality varieties.  

Grape Powdery Mildew infection of young berries

This strategy might also be employed to reduce susceptibility to another disease called Powdery Mildew which requires frequent sprays or sulfur dustings even in dry environments like that of California. There are even susceptibility differences between Vitis vinifera varieties which might be able to be moved.

Rot Reduction

Tight clustered Chardonnay is prone to rot diseases

BotrytisBunch Rot is most problematic in grape varieties where the clusters are very "tight" (e.g. Riesling, Pinot Noir, Chardonnay, Zinfandel) and less problematic in varieties where the cluster is looser with more stem between the berries (e.g. Merlot, Cabernet Sauvignon).  It is possible to loosen up clusters with a very well-timed spray of the plant hormone gibberellic acid, but that is difficult and can affect the next year's yields.

Loose clustered Merlot is less likely to rot

If the genes which control the development of the main cluster stem (rachis) could be identified, it would be possible to make less rot-prone versions of great varieties and thus reduce the amount of waste caused by Botrytis.

Fall symptoms of Leafroll virus infection

Viral Diseases

Viral diseases of grapes, spread by insects, can shorten the productive life of a given vineyard planting. If you tour grape growing regions in the fall you may see vines with leaves that have turned red. It's sort of pretty, but it means that those vines are infected with Leafroll Virus - spread by mealy bugs.  Such vineyards bear progressively less fruit and fruit of lower quality until the point at which it becomes necessary to tear out those vines and re-plant - often years before it would otherwise be necessary.  A transgenic solution to that virus is definitely possible as it was with a virus that nearly destroyed the Hawaiian Papaya Industry. 

Pierce's Disease - A Potentially Existential Threat

Grapes are also susceptible to a disease which actually kills the entire vine.  The pathogen is bacteria-like and is endemic to various riparian plants in the US.  If an insect vector happens to move from those plants to a vineyard, it can lead to an infection called Pierce's Disease which will soon destroy the vine. In the Southeastern US this pathogen makes it impossible to grow the European grape varieties.  In California infections were known, but were relatively rare because the native vector (the bluegreen sharpshooter) didn't tend to move very far into a vineyard.  Then in the 1994, a new vector called the Glassy Winged Sharpshooter was introduced into Southern California and started vectoring Pierce's disease into vineyards on a large scale.  For a while it looked like this new combination would be the sort of existential threat now facing the Florida Orange industry.  Fortunately, growers learned how to check the population of the vector by spraying it when it was in neighboring citrus groves, before it moved to the grapes.  Also, it appears that some degree of natural biocontrol has kicked-in to keep the overall population of glassy winged sharpshooters manageable.  Should this disease become a major problem in the future, a genetic engineering solution might be the only viable solution.

Voluntary "GMO labeling" Would Be Easy for Wine

Because wine grapes can be extremely valuable (e.g. as much as $10-20,000/acre), and because quality is closely connected with the location where they are grown,  "identity preservation" is common in the industry. It would be entirely feasible for grapes which were or were not "GMO" to be kept separate to what ever extent was desired.  So, one winery could proudly label their wine as "improved via biotechnology to provide disease resistance," while the neighboring winery could confidently claim not to be "non-GMO" if they so desired. Again, remember I'm talking about what could happen in a parallel universe where reason prevails. In our universe (as has already been demonstrated in both France and in Mendocino County California) reason quickly yielded to the politics of fear and unfounded concerns about "genetic contamination."

So, there will probably never be commercial "GMO grapes" in our universe, but that doesn't change the fact that it is a cool concept.

You are welcome to comment here and/or to email me at savage.sd@gmail.com

Colorado Chardonnay image SDSavage

Grape Downy Mildew (Plasmopara viticola) image from the University of Georgia Photo Archive

Grape Powdery Mildew image from Wikipedia

Rotting Chardonnay image SDSavage

Merlot image from Naotake Murayama.  

Leafroll virus image from Oklahoma State University

When A Genetic Solution Saved The French Wine Industry

The mid to late 1800s was a very difficult time for the European wine grape industry.  New pests associated with native North American grape species made their way to the "Old World" because of transport between the continents.  I recently wrote about how a fungal disease called downy mildew nearly destroyed the industry until it was saved by the accidental discovery of an effective chemical fungicide.


In today's post I'm going to talk about an insect pest that was introduced to Europe in the same era.  It was a a root feeding relative of aphid called Phylloxera.  Native American grapes are quite tolerant to it, but when it started attacking the roots of the European, Vitis vinifera grapes it began debilitating and finally killing the vines.  It may have arrived in the 1850s, but was first recognized in 1863.  This was an extremely trumatic economic and social crisis.  More than 1 million hectares of vines were killed and many more debilitated before a solution was finally found. In this case the ultimate solution was found via genetics  (There are many good sources about the extended drama and real economic suffering associated with this this crisis - see links below)

1888 drawing of what is now classified as Daktulosphaira vitifoliae

The Genetic-based Technology Solution

The solution to Phylloxera that was ultimately applied seems obvious with hindsight.  Since the North American grape species had always tolerated this pest, why not use them as "rootstocks" and graft the revered European varieties on top of them?  Grafting of desired varieties onto the roots of less desirable, but either more hardy or already established versions of the same crop was not a new idea.  That had been practiced for thousands of years for many tree and vine crops.  The ancient Hebrew and Christian scriptures are full of literary images based on the concept of grafting.  It was an ancient, practical solution - but what it amounted to was a rather dramatic "genetic modification" of the roots of millions acres of European grapes (and eventually grapes around the world).

This idea of grafting onto foreign, low quality grapes was hard to swallow for much of the French wine community of the day.  Their questions included:

• Will treasured, traditional varieties like Pinot Noir grafted on this inferior sort of grape still make a classic red Burgundy worthy of each specific appellation in that district?  
• Will this new reality mess with the quality that was traditionally achieved with complex blend of varieties in a region like Bordeaux?
• Will this new pest eventually overcome this solution?  
• Should wine made from grapes grafted on American rootstocks be labeled as GMO?

Ok.  They didn't ask the last question in the 1800s, but there was a long-running and eventually meaningless debate about whether pre-Phylloxera wines were better.

An Ironic Modern Rejection of a Genetic Save for Grapes

Flash forward to modern times.  There is a nematode pest which spreads a grape disease called Fanleaf Virus.  Once the soil on a given site has been contaminated with that small, roundworm parasite and the virus, if you plant vines there, even after ten years with no grapes, after a few years they decline and die.  This is actually a problem nearly as old as Phylloxera, but fortunately it does not spread easily.  Once people understood how it works, it has been mainly limited to certain areas in France, some other European countries, and a few places in California.  The sad part is that there are significant hectares of vineyard sites in premium wine growing districts that can't be used to make great wine because of this issue.  For many crops, one can just move away from such problems, but for wine the unique combination of climate and soil can create conditions which are legitimately important for quality.  The term "Terroir" is used to describe that essence of place.  Fanleaf virus and its vector severely compromise the Terroir wherever they occur.

With the advent of biotechnology there was the possibility of a better solution for Fanleaf contaminated sites that never existed before (there were some nematode resistant rootstocks but they were undesirable for other reasons).  A rootstock was developed which was resistant to the virus using the same approach that saved the Hawaiian papaya industry.  With that genetic solution, high quality grapes could be successfully grown on on compromised sites in a way directly analogous to how American grape rootstocks saved the crop from Phylloxera in the 1800s.

One might imagine that with the tremendous esteem for terroir in the wine French wine industry, this means of rehabilitating highly valued vineyard sites would be eagerly embraced by the wine industry. Unfortunately that was not the case.  There were some modest field tests of this rootstock being conducted by a French governmental agency in 2010.  There was a great deal of public controversy about this, little industry defense, and ultimately activists destroyed those trials on August 15, 2010.  Their stated concern was that this new rootstock could "genetically contaminate" the rest of the grape crop.  Let me explain why that fear was irrational to an absurd degree:

As this post describes, back in the late 1800s, the entire French and European grape crop was replanted on American rootstocks which differ from the Vitis vinifera grapes by probably hundreds of genes or versions of genes.  No one has ever needed to worry about "genetic contamination" from those millions of acres of genetically "foreign" rootstocks even though they have been present for over 100 years.  If those industry-saving American rootstocks (which are normally only underground) ever happened to get the chance to flower and generate pollen, it still wouldn't matter because grapes are never grown from seed. They are always grown from cuttings or buds.  That is also why you can plant blocks of different grape varieties side by side with no issue of "contamination."  So why would rootstocks with ONE very useful gene inserted by genetic engineering suddenly be a contamination risk?  There was absolutely no risk!

As far as I can tell, the grape industries in France and elsewhere were sufficiently intimidated by the magnitude and ferocity of the irrational response to have decided to simply live with some of their best vineyard sites being compromised. If someone in those industries knows differently, please let me know.

You are welcome to comment here and/or to email me at savage.sd@gmail.com.  I tweet about new posts @grapedoc

grape image mine
Phylloxera drawing from Wikimedia Commons

There are many websites which describe this traumatic event for the European grape industry and for the economy as a whole (Wikipedia: Great French Wine Blight, a review of what sounds like an interesting book about this by Christy Campbell,  a nice summary from 1986 in Wine Tidings republished  by The Wampum Keeper).