Fighting Blight with a new twist on Plant Breeding
Late blight is a devastating disease, which can turn a whole potato crop into a soggy, foul-smelling heap. It is caused by the fungus-like microbe Phytophthora infestans. This disease-causing organism favours mild, wet conditions and can therefore be a severe problem during the typical British summer.
To protect our potatoes, UK farmers use large amounts of chemical fungicides, often spraying as many as 17 times a season, a practice that comes at a huge financial and environmental cost. In bad years organic farmers are permitted to use copper-based fungicides with approval, but these are also harmful.
At the Norwich Research Park, scientists are half way through a three-year trial, which may provide an alternative to heavy chemical usage. The researchers, who are part of the Sainsbury Laboratory, are growing potato plants engineered to be resistant to late blight infection. Each year, the trial covers an area of about 200 square metres and involves growing a few hundred plants each year.
To cause infection, a microbe must enter a plant’s cells undetected. If it is recognised, the plant will activate its natural defences and infection will be fought off. Although resistance genes that recognise late blight, were bred into European potato varieties over 50 years ago, the late blight organism has since evolved to evade detection by these genes.
At the Sainsbury Laboratory, scientists studying wild potatoes have been able to identify and isolate effective resistance genes from wild South American potatoes. If these genes can be successfully introduced into UK potato plants, then it is hoped that the potato varieties we know and love will also become blight resistant.
This technology is seen as the next step to traditional plant breeding, where plants with desirable characteristics are interbred to produce ideal offspring. In this case however, the parent plants are so different that it would be essentially impossible to produce blight resistant potatoes that still retain all of the characteristics (yield, taste, texture etc) of the potato varieties that are favoured by consumers and industry.
Although genetic engineering is often associated with concerns over food safety, the results from 25 years of EU-funded research show no scientific evidence that this technology poses higher risks for the environment, or for food and feed safety than conventional plants.
The potatoes being grown in this trial will not be available commercially. The purpose of this trial is to test the efficacy of the blight resistance genes. Should this trial be successful we hope that companies will want in the future to licence the genes and deploy them in commercial crops.
Whilst our dependence on potatoes as a food source is far removed from 1840’s Ireland, they remain an important staple and the world’s fourth-largest food crop. We face significant challenges in producing enough affordable food for a growing population. If genetic engineering can help improve yields and reduce labour costs, then this technology is likely to prove vital in safeguarding future food security.