A Primer on Pinot noir Genetics

From John, December 3rd, 2017

Pinot noir (and Chardonnay to a lesser extent) is well known for consisting of a multitude of clones. You may ask “what is a clone?”

Within the Pinot noir genome are a number of variants which confer differences in things as diverse as how the vines grow (droit and fin), size and shape of clusters, vigor of the vine and so on.  Within the Pinot noir genome are both chromosomes and free circular pieces of DNA called plasmids, both of which express genetic characteristics. The combination of all of this genetic material is what constitutes a clone.

The origin of plasmids is not particularly clear. Agricultural scientists like to refer to these pieces of genetic material as viruses but that is most likely a simplification. Pinot noir is thought to be genetically unstable and this may in part be due to changes (mutations) in the structure of the plasmids.

Over many generations, farmers in Burgundy have selected new clones that occasionally pop up in their vineyard…a vine with smaller clusters, or tinier berries, or darker color for instance.  They then propagate those clones and, if the wine improves, those clones become a long term part of the massale (the selection of disparate clones) in that vineyard. This huge selection of genetic diversity within the great Burgundian vineyards has certainly contributed to the justifiably stellar reputation of these vineyards.

In the 1950’s, agricultural scientists both in California and France discovered that they could “sanitize” vines by destroying the plasmids in dormant Pinot noir and Chardonnay plant material by subjecting the cuttings to excessive heat. Because plasmid DNA is much more heat labile, it can be destroyed while the chromosomes remain. The resulting plant material produced vines with simpler clusters of large berries and generally more vigorous growth characteristics.  These new “sanitized” vines are referred to as “indexed vines”.

I would argue that with the genetically-modified large clusters and large crops, the resulting wines are significantly inferior to wines made from the original non heat-treated vines.  The controversy over “indexed vines” continues to this day.   Now, if you want to purchase new cuttings from purveyors such as UC Davis, they must be indexed in order to be shipped to Oregon. It is a classic battle between industrial agriculture which strives for more production through genetic manipulation and small family farmers who want to produce quality food from old proven cultivars.

In my 35 years of experience, I have found that wines made from indexed vines (such as UC Davis 108 Chardonnay and Dijon PInot noir and Chardonnay) are just not as good as those made from old original clones.  I encourage new vineyards to consider this when choosing cultivars to plant.

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