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A Wineglass of Genes

by Andrew McNaughton

Whether we prefer a merlot or chardonnay, a riesling or a sauvignon, this diversity comes from not so much a ‘gene pool’ as a ‘gene puddle’. We may have strong preferences for a particular grape variety, but we are all drinking essentially the same thing. That may seem hard to swallow, especially when you consider the number of people making livings growing, producing, tasting and marketing a staggering variety of wines. Entire regions of Europe are defined by their particular variety: Bordeaux, Champagne and Burgundy to name a few. Almost all wines however come from the grape Vitis vinifera subsp. vinifera, the variation of wine types comes from intensive selective breeding within this one sub-species. Well, almost.

It’s generally thought the subspecies vinifera originated in the Near East, that is, somewhere between India and the Mediterranean, including Iran. As the grape spread west is was bred for an ever varied stable of wines, on the surface it would appear to have a highly diverse ancestry. In practice it seems the only injection of new genetic material came from a wild species of European grape Vitis vinifera subsp. sylvestris. This happened as vinifera marched its way across Europe and interbred with the wild sylvestris sub species.

If you’re reading this whilst sipping a fine pinot, you may wonder what the problem is? Wines are forever improving, they’re grown in many regions of the world, surely this indicates a thriving and robust genetic stock? If you’ve ever bought a bottle of wine based upon nothing more than a nice label, you’l appreciate how looks can be deceiving. Grapes have indeed been bred intensively over the centuries, but largely within the same variety. Yet, even within the same variety there exists diversity of habit, taste, vigour and flavour. In the same way the members of your immediate family still show considerable diversity in shape, size and a host of other characteristics, despite being closely related genetically. Thereby providing a sense of relief for many people as they glance around at their family reunion.

It cannot be denied selective breeding has resulted in a dazzling range of wines, just look at your local supermarket’s wine shelves. The problem is, selections have been made for characteristics favourable to making better wine. As grape growing is a highly competitive industry, vegetative propagation has become standard practice to ensure favourable characteristics are reproduced faithfully. The grape is the most valuable horticultural crop in the world, with about 8 million hectares grown; this is not the place for unpredictable performances. Commercially sensible, but a potential bottle neck to genetic diversity.

Resistance to pathogens such as bacteria and fungi haven’t been bred for, particularly once agri-chemicals became common in the 1950’s. The incentive for breeding resistance plunged when simply spraying grape vines with fungicides could rid even the feeblest of grapes of infection. Unfortunately, the pathogens have developed resistance due to being subjected to intense selective pressure. The day of reckoning now beckons, as vinifera, in its present forms, lacks enough genetic diversity to adapt to pesticide resistant pathogens.

But all is not lost, vinifera does contain ample genetic diversity, perhaps ten times more than ourselves, it simply hasn’t been utilised. Characteristics for good wine have been honed and propagated, but now may be the time where a different pool of genes are exploited for pathogen resistance. Using modern DNA sequencing technology, these ‘hidden’ genetic pools can be pinpointed and used to steer grape breeding in a much more predictable, and commercially attractive manner. Of course if you’re philosophically opposed to genetic engineering, you may have to switch to ... tea?
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