Wine’s genetic diversity: Thank goodness we’re not coffee

Wine has a diversity issue. Wine actually has several diversity issues, but I’m not prepared to deal with the massive and significant question of non-white non-male winemakers (today). The much easier diversity question is about the wine grapes themselves. And even though it’s an issue, and one that’s been rightfully earning more press of late, wine grapes have the potential to be a good deal better off than most crops. The problem is of our own making, and we should be able to unmake it.

Arabica coffee varieties, according to a recent genetic survey, share 98.8% of their genes in common. That’s an estimate made by sampling both wild and cultivated plants (781 sequences in total) from around the world. So, even if coffee breeders try their darndest to increase the diversity of cultivated coffee plants – which they are, because genetic diversity means better resilience against threats like infectious diseases and climate change – they only have so much room to work. The survey found that wild plants were more genetically diverse than cultivated ones. The breeding stock can be improved. But compare coffee to maize, for which something like 30% of the genome varies across all of the plants on the planet, and there’s not that much room.

Wine grapes are like maize, not like coffee. Both maize and Vitis are, in fact, extraordinarily diverse. No shortage of room here. What’s most curious for wine grapes, though, is that the difference between the genetic diversity of wild and cultivated vines isn’t that great. When humans domesticate a species, we create a genetic “bottleneck” (Nature has a nice image here), reducing genetic variability in the new crop. For wine grapes, the bottleneck was “weak;” the reduction wasn’t that dramatic. (Coffee, by the way, suffered a very severe bottleneck.) And earlier this year, a genetic survey of wild and cultivated grapevines in the Republic of Georgia, where grapes were first domesticated to the best of our knowledge, still found plenty of diversity in wild grapevines that doesn’t overlap with cultivated varieties and which have yet to be explored.

Unlike coffee, the real problem with wine grapes isn’t that the genetic diversity isn’t available, in wild or even in cultivated plants. The problem is that we’ve artificially selected for an incredibly narrow set of vines, over and over again, through clonal selection to replicate what we think is the best of the best. To recapture the genetic diversity that might help wine combat disease and changing climates and whatever else the next century or three throws our way, we need to undo the relatively recent work of the modern wine world.

The numerous research teams working around the world on the grape diversity issue have a great big spectrum of possibility out in front of them. That’s a good reason to be hopeful. And to be sorry for the coffee guys.

14 thoughts on “Wine’s genetic diversity: Thank goodness we’re not coffee

  1. Hey, I enjoy your posts and like your style.

    Just a minor bone to pick. Here’s a quote from your article:
    “that doesn’t overlap with cultivated varietals and which have yet to be explored.”

    Its that word ‘varietal’. Grapevines are not varietals, wine made from them is ‘varietal wine’. ‘Varietal’ is an adjective, or sometimes, I guess, a shorthand noun for wines made from one variety. But not the vine itself. Proper terms include ‘variety’ or ‘cultivar’.

    BTW – We have a project at Cornell called Vitis Gen that is trying to exploit some of that genetic diversity to turbocharge (conventional) grape breeding programs. Check it out at http://www.vitisgen.org. Good fodder for future blog posts.

    Regards,

    • That’s not a bone to pick, Tim, it’s a correction, and it’s one I’m usually complaining about on other folks’ posts instead of making myself. Well, now I have a good example of what happens when you finish something late at night and don’t proofread it to share with my next writing class.
      I’ve been following Vitis Gen with interest and look forward to seeing what happens next. Thanks for the pointer.

      • I see ‘varietals’ creeping in everywhere in the trade press. I’m on a mission to point it out to them (writers, students here at Cornell) and do my part to stamp it out.
        -Regards, and thanks for the response.

        • Tim, I’m not sure that I’m on a crusade but, seriously, it bugs me too. I’m embarrassed for my late-night self. Thanks again!

  2. One more comment: We have in the Eastern United States something on the order of 30 ‘hybrid’ wine cultivars, both the conventional, older ‘French Hybrids’ and newer varieties developed at Cornell and Minnesota (to name two examples) and although they are clonally propagated (like all grapevines), there is a lot of diversity represented by their parents, as they are the result of complex crosses of hybrids derived from american wild vines (V. rupestris, V. riparia, V. cinerea, V. rupestris, V. labrusca, V. aestivalis and the only european species, V vinifera.

    • Very true, and good point. I know that Cornell has a long history of working with various cold-hardy hybrids. To be honest, I usually look at that history and think of it as a product of needing cold-hardiness particularly in the absence of contemporary vit techniques, but that’s very much an outsider’s perspective. I think it’s also a mixed blessing, because on the one hand this diverse experimentation happened and on the other maybe the focus wasn’t on wine quality all of the time, which sets hybrids back as far as fine wine making (though I’m not willing to leave the winemaking needs, culture, and preferences of the early hybrid winemakers out of this, either). It seems to put you a step forward in creating hybrids, but maybe a step back in creating hybrids that most quality-focused winemakers and drinkers are interested in accepting.

      • Re the hybrids: Yes, your knowledge of the hybrids and wine quality is out of date.
        Originally, the ‘french hybrids’ (eg. from hybridizers Seibel, Seyve-Villard, etc) were developed to survive phylloxera. They were brought to the NE US principally because they offered non-labrusca, vinifera-like sensory attributes (one early goal was to make a dry red table wine from grapes grown in the east, not possible with labrusca types) and somewhat better cold hardiness than V. vinifera. The large wine companies (Taylors, Brights) selected some of these for their product lines, most often with processing efficiency at the winery the main goal. ‘Aurore’, aka ‘Seibel 5279’, for example was a widely planted white because it ripens a month before Concord, is very productive and could be fermented and out of the tanks before the Concord for ‘Lake Country Red’ came in.

        But others like the white cultivar Vignoles, (AKA ‘Ravat 51’, for french hybridizer J. F. Ravat) make classic, aromatic fine wines – that if they were V.vinifera – might possibly be placed in the pantheon of elite varieties.

        From our program at Cornell, I’d cite ‘Traminette’ as an example of a hybrid variety capable of making high quality, fine wines (Yes, Gewurz-like). There are others as well: ‘Norton’ eg, and ‘Chambourcin’, ‘Vidal blanc’.

        The other point is: V. vinifera classic cultivars have been around since the 1600s(?), and have little disease resistance. Here in NY there are 5 major diseases that can result in unharvestable fruit – and prompt a rigorous spray program. Genetics could give the world less disease-prone cultivars that could be sprayed far less than classic V. vinifera ones.

        Main point here: Low quality hybrids for plonky wines is an old, but enduring story. New varieties (and better winemaking/viticulture) are making ‘fine wines’, but are not well known yet. There is viticultural ‘species-ism’ or ‘varietal wine-ism’ that biases much of the wine world against interspecific hybrids.

        These are not available in NZ! But you should visit the NE USA and give some of them a try.

        • With absolutely no disrespect either to the excellent Cornell program or to people who enjoy the hybrids you named, Tim, they’re just not for everyone. I’ve had quite a few nortons, chambourcins, and vidal blancs. One of the nortons was something I’d drink again, and vidal makes for some lovely dessert whites. As for the rest, I’d stick with water or beer if they were the wine being poured. As of 2013, which was when I last had the opportunity to taste NE USA hybrids, the quality just wasn’t there yet.

          • I take your point, but I think you are still being overly broad in your characterization of hybrid winegrape varieties – which is actually rather a broad group (eg,Vignoles is not Vidal blanc). Yes these are ‘niche’ products in the grand scheme of the wine world, and many (particularly the reds, eg. chambourcin – still an old traditional French hybrid) don’t compare with the international V. vinifera varieties.
            There’s also a reason, subject of recent investigations in the Sacks lab here at Cornell (http://pubs.acs.org/doi/abs/10.1021/jf5023274) why many of the traditional red hybrids lack tannins in the wine – i.e. there are proteins that bind them, so they aren’t as extractable as their vinifera counterparts. It has been hypothesized that this phenomenon is genetically related to North American grape species having evolved in the presence of powdery mildew, downy mildew, and black rot – i.e. that these proteins that protect the vine from pathogens also bind tannins and they precipitate out during winemaking.

            Which points to V. vinifera cultivars major drawback: Lack of resistance to these fungal pathogens and the associated need to repeatedly apply fungicides to V. vinifera cultivars to produce marketable fruit. Wine grapes are certainly in the top 6 crops worldwide in terms of tons of fungicides applied annually to them. In our climate in upstate NY, for extremely susceptible Chardonnay, that translates into perhaps 10-15 fungicide sprays per season, while many of the hybrids get 3-6. Even in dry climates, extreme powdery mildew susceptibility is a huge driver of fungicide use (including ‘organic’ fungicides’) – and a major weakness of the classic international varieties.

            Do we want varieties that we can grow with fewer chemical inputs? If so, genes from varieties clonally propagated in the 1600s and 1700s – before powdery mildew arrived in Europe – just won’t cut it.

            Genes from north American species which have evolved with the 20 or so native Vitis sp. In the New World have the potential to address this major drawback. One example being UC Davis professor Andy Walker’s varieties with Pierce’s disease resistance – which through conventional backcrosses now have >98% V. vinifera genetics AND Pierce’s disease resistance. (Youtube video here: https://www.youtube.com/watch?v=hbtF3WdqftI ) .
            Will any of these new varieties produce wines comparable to the classic international varieties? Maybe. Even if the wines are indistinguishable from Cabernet Sauvignon, they still won’t be marketed with that varietal name. Since they were still produced by hybridization (i.e. classic breeding) they are hybrids.
            Which, I think, may have been the point of your original article: i.e. that there is germplasm out there that hasn’t been exploited by our relatively narrow group of elite cultivars.

          • Tim, thanks again for elaborating the additional information. I’m not trying to say that hybrids can’t make great wine now or won’t make consistently great wine in the future, and certainly not that new grape development programs don’t have an important place in the industry. I’m saying that the hybrid wines I’ve had to date have been underwhelming. I still look forward to trying more of them when I have the chance.

  3. Tim I think it is going to be a losing battle in terminology. I don’t think I have heard the use of “cultivars” for many years now. I just came back from the Ningxia region in China – an area that is getting a lot of positive press, not a view I now share. It is clear that the industry is suffering form very poor quality cultivar rootstocks that were often diseased, not true to claimed variety (Carmenere among the Cabs!)and truly not suited to the short growing season, or the need to bury trunks under soils through winters in that part of China The viticulturalist at Pernod Ricard in the region is experimenting with non-Vinifera varietals to see if they can find vines that do not need this burying process. China has only started to allow new cultivars into vineyard use, but the reverse problem is now holding the industry back. Consumers only know Cabernet Sauvignon, so very hard to shift that demand to “varietals” that are more suited to the region like Shiraz and Malbec.

    • Maybe not ‘cultivars’, but surely one can use the word ‘variety’ rather than ‘varietals’ to refer to the grapevine itself, as ‘varietal’ refers to products (wine) of the grapevine.

      • We’re losing resolution in a lot of popular media/public language, it seems. Language is always evolving, and maybe the community is self-correcting for feeling as though it doesn’t need so much detail, but I think there might be something interesting going on here. Time for me to spend some more time thinking.

    • Chris, do you think there’s a founder effect here in terms of how the colleagues you met in China use “varietal?” Were they instructed early on by one person who used the term imprecisely, took that as their baseline for correct usage, and have been spreading it ever since? The China situation seems very complicated. When you have a population with very little grasp of quality outside of identifying with specific brands, and a labor culture that doesn’t reliably prioritize continuous improvement, and a culture that’s very new to wine, plus a cultural or racial stigma that I imagine might keep them from always receiving (or maybe even being receptive to) the best advice, and all compounded with a desire to grow quickly and a lot of investment capital, I can very easily imagine vast wine producing empires being built on poor foundations. I know very little about the situation, or Chinese wines, and would like to learn more.

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