Genetic modification and the Great British potato

PUBLISHED: 17:24 25 February 2014 | UPDATED: 09:44 27 February 2014

Potatoes come in all shapes, sizes and colours.
© Perry French, via Flickr. Reproduced under a CC BY-ND 2.0 license

Potatoes come in all shapes, sizes and colours. © Perry French, via Flickr. Reproduced under a CC BY-ND 2.0 license

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Everyone loves a good roast or jacket potato, a bag of chips or a pile of creamy mash – but the Great British potato is constantly under threat from weather and disease. Lisa Martin discusses some of the pressures that potato growers face, and how a controversial genetic technology could save the humble spud.

Could GM technology save the Great British chip?  
© S. Leggio / Sicilystockphoto.com. Reproduced under a CC BY 2.0 licenseCould GM technology save the Great British chip? © S. Leggio / Sicilystockphoto.com. Reproduced under a CC BY 2.0 license

Potatoes are one of the UK’s best-loved foods. They’re cheap, versatile and very tasty – especially when sliced, fried and covered in salt and vinegar! As a nation, the UK eats over 1.6 million tonnes of chips each year and the potato industry contributes more than £4.7 billion to the British economy, so potatoes are a very important crop for British growers.

But potato growers constantly battle with forces beyond their control in order to meet the country’s demand.

Late blight can cause potato plants to die and the potatoes themselves to be discoloured and susceptible to soft rot. / © Ben Millett, via Flickr. Reproduced under a CC BY-NC-ND 2.0 license.Late blight can cause potato plants to die and the potatoes themselves to be discoloured and susceptible to soft rot. / © Ben Millett, via Flickr. Reproduced under a CC BY-NC-ND 2.0 license.

Many potato growers sow their fields in the spring, but in the last couple of years, this time of year has been cold and wet – very wet! This delays potato planting and has a knock-on effect throughout the year, resulting in significantly lower crop yields, and increasing our reliance on potatoes imported from abroad.

Another challenge to our potato harvest is a disease called late blight; a fungal infection caused by the organism Phytophthora infestans. This pathogen causes the decay of the potato plant’s leaves, and if it strikes early in the growing period, the crop will fail. Any tubers (the potatoes under the ground) that do develop are discoloured and very susceptible to soft rot.

Late blight is not a new disease; in fact, the Irish potato famine of the 1840s can be attributed to this very organism. Phytophthora thrives in damp conditions – especially in humidity and in temperatures above 10°C. It is spread from one area to another by the wind – so the recent UK storms, floods and the mild temperatures we are currently enjoying are certainly not going to help this year’s yields!

If you’re thinking of sowing potatoes in your veg patch this year, there are several things you can do.

Firstly, make sure you sow seed potatoes that have originated in the UK – those imported from abroad can be a source of late blight disease.

Since the Phytophthora organism can overwinter in seed potatoes from previous years, it’s best not to sow your own overwintered potatoes, and to make sure you have dug up every last tuber from your previous crop. Choose seed potatoes that are of a naturally late blight-resistant variety: you can find out which varieties are recommended by visiting the Potato Council’s database: www.varieties.potato.org.uk/menu.php.

When planting your potatoes, make sure they are well spaced, and when watering, try not to spray the foliage; this helps to reduce the spread of disease. To avoid over-watering your plants, try digging in some good quality mulch to help the soil retain moisture. There are lots of other useful tips for potato growers available in this Garden Organic factsheet: www.gardenorganic.org.uk/factsheets/dc17.php.

For potato growers operating on a commercial scale, chemical pesticides are often used to help control late blight, but there might be another way…

People are often worried about genetic modification (GM), whether it is safe to eat GM food, and whether it is damaging to the environment. Some argue that it is wrong to “mess with nature”. However, in my view, as a technology, GM can be a very useful technology indeed.

Genetic modification is when scientists take a useful gene from one organism and splice it into the DNA of another. A good example of where this has been done successfully is in the production of insulin for the management of Type 1 diabetes.

Before GM technology came along, diabetics had to inject themselves with insulin extracted from pigs, because this was the closest available match to human insulin. Obtaining insulin in this way was very expensive, not to mention a wasteful use of pigs! Now, the gene for human insulin has been transplanted into bacterial DNA so that we can quickly and cheaply grow vast quantities of bacteria, extract the useful substance and treat many more people than was possible before.

Genetically modified plants have received some bad press in recent years, particularly in the US. Here, large agricultural chemical companies have exploited the technology to develop crops resistant to their specific weed-killers, effectively forcing growers to use only that company’s products.

A scientific study published in 2012 also claimed to have found strong evidence that mice fed with GM maize were more likely to develop cancer. However, it is important to note that this study was later found to be highly flawed and was eventually officially retracted.

Scientists from a research institution called The Sainsbury Laboratory, based in Norwich, have recently completed a trial to investigate a variety of potato that has been genetically modified to be resistant to late blight. Having identified a wild relative of the potato plant in South America, which has a gene that makes it resistant to late blight infection, the scientists transplanted this gene into the DNA of Desiree potato plants.

They sowed these in a field, along with some non-GM potatoes of the same variety, and waited for late blight to set in. Fortunately (for the scientists at least!), 2012 was a very wet year – as you may remember! – and created the ideal conditions for Phytophthera to spread and infect.

At the end of the trial, the researchers found that 100% of the non-GM potatoes had been infected with late blight, while none of the GM plants had succumbed. In addition, the yield of potatoes harvested from the GM plants was much greater: 6–13kg of potatoes per block of 16 plants, compared to just 1.6–5kg per block in the non-GM trial plots. You can read the scientific paper that was recently published about this work here: www.rstb.royalsocietypublishing.org/content/369/1639/20130087.full.

Of course, we can use traditional breeding techniques to develop disease-resistant crop varieties, but it is a very slow and somewhat trial-and-error process. The advantage of GM in this sense is that it is much quicker, we know exactly which genes are being transferred to our new variety, and we can scientifically predict how it will behave.

What are your thoughts on GM technology? Do you think it is worth a try to save the Great British potato?

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