Wine gets CRISPR


Winner of our wine writing competition Hrishi Poola studied biology and worked in the biotech industry for nearly a decade. Here he brings us up to date on the latest applications of gene technology, to wine inter alia. 

'If we define “beauty” as having blue eyes (and only blue eyes), then we will, indeed, find a “gene for beauty.” If we define “intelligence” as the performance on only one kind of test, then we will, indeed, find a “gene for intelligence.” The genome is only a mirror for the breadth or narrowness of human imagination.’ Siddhartha Mukherjee, The Gene (Scribner, 2016)

In 1864 in a dimly lit Moravian monastery, Gregor Mendel, an Augustinian monk, had his eureka moment tending to garden peas. A hunch about the laws of heredity turned into the discovery of nature's invisible hand. What he called elemente would eventually come to be known as genes in 1909 (Darwin, Mendel's contemporary, never made the connection). Aristotle first speculated about heredity as a transfer of instructions or a message nearly 20 centuries before.

Mendel would be shocked at our understanding of genetics today, especially as we cross the chasm from discovery to engineering, from ‘reading’ to ‘writing’. Then again, he might not. Grape-growers and winemakers have been conducting a kind of slow-motion genetic engineering since they first domesticated wine grapes in south-eastern Georgia 8,000 years ago. Selecting and breeding grapes with desired traits expanded to an industrial scale among ancient Egyptians, Greeks, Etruscans and Romans. Mother Nature herself is a kind of genetic engineer, routinely sliding genes from one species to another.

And there have always been the two minds of the winemaker: the grape is our master, we are masters of the grape. Humility and hubris. Arguably, the great winemakers boast healthy doses of both, although our understanding of genetics and the grape gene clearly tilts to the latter. Today's excitement is around CRISPR/Cas-9, or CRISPR for short. Without getting too geeky, CRISPR is a biological Microsoft Word, a tool to edit the genome with startling precision and efficiency. Cas9 is an enzyme that snips DNA and CRISPR is a genetic sequence that guides Cas9 to exactly where to snip. Compared with traditional methods and other gene-editing alternatives (TALENS, ZFN and RNAi, for example), CRISPR is efficient, powerful, versatile, relatively cheap, easy-to-use and can target multiple sites. Another upside is that it's nature-made. Microbes have been using it for millions of years as a bacterial immune system against viruses. Bacteria use CRISPR to chop up viral DNA and stave off viral attack. Scientists are now harnessing this ancient tool for almost anything under the sun.

Genetic engineering is often framed in a dystopian light, a Pandora's box of ‘designer babies', playing God and corporate greed (vide Monsanto's glyphosate/RoundUp-resistant soybeans and rice). Despite sinister headlines, the reality is that CRISPR is now doing what was once thought impossible, revolutionising research, curing disease, improving our supply of food (and wine), altering human embryos and even resurrecting the woolly mammoth. CRISPR features its own drawbacks, including off-target effects (akin to making a typo). However, CRISPR tools are getting better and more sophisticated every day.

MIT Technology Review has hailed CRISPR as the biggest biotech discovery of the century. Pharmaceutical companies such as Novartis and CRISPR Therapeutics are using CRISPR to make your immune cells attack cancer. Chances are that if you've eaten yogurt, it's been made using CRISPR-ised bacterial cultures. It's being used to ripen tomatoes in more northerly latitudes and at higher yields, as well as in rice to prevent bacterial blight caused by Xanthomonas oryzae pv. oryzae, a huge problem in Asia and Africa. In Florida, citrus farmers are discovering that CRISPR can be used to prevent citrus canker and citrus greening disease. In Beijing, scientists are using CRISPR to design wheat that is resistant to powdery mildew. We're even discussing the possibility of using CRISPR ‘gene drives’ to wipe malaria-carrying mosquitos off the planet, though we don't yet know the unintended consequences of altering entire ecosystems in one fell swoop.

Then there is CRISPR wine. CRISPR is being tested in the vineyard and winery to tackle some of wine's biggest challenges. A grape's genetic consistency can be both a blessing and curse. It means that Chardonnay is the same grape variety passed down through the centuries from its ancestral home in eastern France (though it has dozens of clones). It means that we, more or less, know what we're getting from vine to glass. However, a grape's lack of genetic diversity also makes it vulnerable to pests and environmental shocks. Think back to the phylloxera bug in the late nineteenth century that ravaged vineyards across Europe, many of which never recovered. Is there a way to keep the flavours and aromas of our beloved grapes while shielding them against evolving threats? Recently, scientists in Lisbon, Portugal, successfully carried out CRISPR modification in wine grapes. Researchers are experimenting with CRISPR to improve sustainability in a warming and an increasingly extreme climate of droughts, monsoon-like rain, floods, fires, frosts, pests and disease. Phylloxera has even made a comeback in places such as the Yarra Valley, as have potentially devastating vine trunk diseases.

Vineyard challenges are expected to only intensify in the coming decades. Pesticide resistance is on the rise while pesticide pipelines continue to shrink, meaning higher and more frequent doses. Take downy mildew. Traditional ways of managing the fungus-like pathogen include pruning to aerate leaves before mildew can germinate, regular monitoring to catch the early signs of yellow blotches across leaves, and regular weather tracking. The copper-based fungicide Bordeaux mixture has been a mainstay of the grape-grower's arsenal (including organic growers) since the 1880s, although environmentally safer synthetic versions exist today. However, battling downy mildew can be costly and time-consuming, requiring 6–12 or even more sprays per growing season. Moreover, vines are becoming increasingly resistant, needing additional and earlier sprays, and climate change is expected to expand downy mildew's range.

USDA-funded researchers at Rutgers University in New Jersey are using CRISPR to make Dijon Chardonnay 76 grapes resistant to downy mildew, reducing the need for fungicidal sprays. The alternative is to breed new, naturally resistant varieties with established varieties, though maintaining flavour has proven tough. In the winery, CRISPR is being tested in yeast. Scientists in Toronto and Milan are applying CRISPR to starter yeast strains to reduce urea production in Chardonnay and Cabernet Sauvignon grape musts. Urea is a precursor to ethyl carbamate, a carcinogen traditionally managed by closely monitoring nitrogen fertilisation and temperature control during storage, which can be costly for small producers. CRISPR opens brand new doors for winemakers using commercial yeasts when it comes to efficiently producing target flavours and reducing harmful compounds and off-odours.

Most producers, appellations and regional authorities will stick to traditional approaches in a warming climate, pushing harvests earlier and expanding the northern limits of grape-growing. For example, Ornellaia in Bolgheri have been planting more Cabernet Franc and less Merlot, altering canopy management by employing less leaf removal in order to protect grapes against sunburn and experimenting with bush-vine (gobelet) training. Some producers in Spain are trialling varieties beyond Tempranillo, including Syrah and Touriga Nacional. INRA in Bordeaux is experimenting in the Pessac-Léognan appellation with dozens of strangers, including Sangiovese, Touriga Nacional, Xinomavro and Assyrtiko, in case the day comes when climate change warps Bordeaux's growing season beyond recognition.

It's still early days and it'll take years before CRISPR moves from experimental greenhouse to the vineyard. If and when it does, appellation rules will have to adapt. I, and I suspect most, would still prefer conventional over gene-edited grapes. Many find such a technological fix hard to swallow, even offensive. A few New World producers may dabble with CRISPR as a plan C and it's hard to imagine classical European appellations adopting it. When it comes to reducing the use of synthetic chemicals, most would rather stick to traditional methods and integrated pest management. Moreover, GMO and 'the Monsanto problem' remains a cultural and regulatory hot potato. How narrowly or broadly should we define genetic modification? What if CRISPR is used only to remove short snippets and not add external DNA? Playing ostrich will not keep this technology from marching forward. The wine community and broader public should wrestle with CRISPR and its risks, benefits, applications and ethics head-on lest we fall short in our ability to manage them.

What do you think? Are we playing with fire? Should we? By how much?