Here is the fourteenth in our series of Another Wine Bytes; information about wine you can use to impress your friends (but not in an obnoxious way, of course!)
AWB #14 – So Just What is a Clone? Aren’t they Human-Animal Hybrids?
While we were visiting vineyards and wineries all over California last month, we heard a number of references to “clones.” Whenever I hear the word “clone,” I remember silly references to “human-animal hybrids” and fears that Dolly the Sheep would lead to Gavin the Goat boy — or some such nonsense as that. But the cloning of grape varietals doesn’t occur in some dark laboratory with a mad scientist.
Actually grapes clones are cuttings that share the identical genetic information with the existing vine from which they are taken. I knew that new grapevines did not come from seeds, but I thought I’d ask an actual grape grower and wine maker to talk more about clones. So I asked a former Texan, and Aggie, to help us out.
John Kelly is the head honcho over at Westwood Winery. John is a former Houstonian and UC Davis-trained biochemist with over 20-years’ winemaking experience including stints at R.H. Philips Vineyards, Stags Leap Wine Cellars, Duckhorn Vineyards and Sonoma-Cutrer Vineyards, before taking over winemaking at Westwood. He also has his own blog aptly named Notes from the Winemaker.
John tells me that grapevine nurseries maintain “mother blocks” to produce cuttings taken from older vines. There is a mother vine for each of the varieties and rootstocks the nursery grafts together, and the group of cuttings produced from each mother vine make up a clonal selection.
Go back far enough in the 19th century and there is one single mother vine for each rootstock. Go back far enough in history and at some point there was one single mother vine for each wine grape variety, ~ says John
Back before Phylloxera nearly took out the European wine industry, especially in France, a grape grower would simply take a cutting from one vineyard and plant it in another. That meant exposing his vineyard to whatever evil insects or fungus were living on the original vine. This sloppy propagation in the late 19th century allowed Phylloxera to be inadvertently introduced to Europe, possibly on imported North American vinestocks or plants. Because Phylloxera is native to North America, the native grape species are partially resistant. By contrast, the European wine grape Vitis vinifera is very susceptible to the insect. That meant the evil little bastard could, and did, attack the French vines, gradually cutting off the flow of nutrients and water to the vine. It then moved across Europe, declaring its own war against the wine industry.
In response to the Phylloxera disaster, researchers worked to develop and maintain clean vinestocks. Now the clones tend to adapt to their environment, because the cuttings from the mother vine are not actually 100 percent genetically identical to the mother vine. Rather, they have adapted to their environment.
This adaptation causes some mutations that result in less susceptibility to pests and other environmental factors.
According to the folks at www.calwineries.com:
Clones have historically been traded between different wine regions throughout the world based on perceived or real similarities in climate and terrain. Often times, there is no track record of exchanging varietals between two regions. Especially when dealing with untested vineyards, vintners often plant several different clones of the same varietal.
Growing a clone in an area where it is not suited will result in mediocre wines. An example of this phenomena occurred when Oregon vintners initially planted Chardonnay clones that had evolved to the warmer temperatures and shorter growing season of California Wine Country. These clones made disappointing wines in their new, cooler home.
However, when cuttings were imported from the cooler, longer growing season of Burgundy, they were a much better match for Oregon’s similar climate. The results were stunning. Oregon has produced a substantial amount of high quality Chardonnay ever since.
John Kelly says this is because the Vitis species show substantial “genetic drift” sporting frequent mutations, including those visible to the untrained eye.
For example, every few years when I walk through my Pinot Noir vineyard I will come across a few clusters (out of many tens of thousands) that are white, not red. If I were to cut the cane that bears a white Pinot cluster, the vines I grow from that wood will also produce white clusters. Go through enough iterations of this selection process with these white grapes and one could derive Pinot Gris, Pinot Blanc and ultimately, Chardonnay (though I doubt this was the literal progression).
It sounds a bit like Joe’s breadmaking. Some bread companies use starters which are over 100 years old to create dependably flavored bread every time. But you don’t always get the exact same result, just because you used the same starter. We could take sourdough starter from San Francisco, and use it to make bread in Houston. But the bread isn’t going to be exactly the same, because of the differences in climate, and the San Francisco Bay is a bit different than the Gulf of Mexico, or even Clear Lake.
Hybrids, says John, are a different story.
Hybrids are sexual crosses between species – in other words, propagated from seeds. When the flowers of different species are crossed the characteristics of the vines grown from the resulting seeds are extremely unpredictable – development of a hybrid requires many decades of painstaking work in the nursery.
Once a hybrid with desirable characteristics has been realized, commercial production is done clonally, via woody propagation of cuttings from the mother vine. Most of the commercial rootstocks are hybrids of different Vitis species. Some wine grape varieties (such as Chambourcin or Seyval blanc) are hybrids of Vitis vinifera with other Vitis species, says John.
So the next time you’re looking out onto a vineyard and someone talks about clones, don’t think about poor Dolly. You’ll know that you’re just hearing about commercial wine grape varietals – and the many painstaking decades of work in the nursery to make sure your wine is coming from the best grapevines possible!
And that’s Another Wine Byte!