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Climate change is transforming how we feed ourselves. Floods, droughts and new diseases can have a big impact on the crops we rely on for food, including staples such as wheat, maize and rice.
Future farmers face a big challenge: feeding everyone on Earth while being kind to the planet. Could genetically modified food be the answer?
Discover which foods can be genetically modified, how they can be improved, and whether people should worry about eating them.
Genetically modified crops are plants which have had their DNA changed by scientists to create desired traits, often by adding just one gene from a close wild relative.
For example, GM crops can be engineered to require less water to grow or to resist diseases or pests. More ambitious projects are underway to engineer crops that make their own fertiliser. This type of technology could be key in making some of our most important food crops more resilient in the face of climate change, and it could decrease the chemicals and energy needed to grow them.
Wheat is the most commonly grown crop across the world by acreage. It is often used to make bread, pasta and noodles, and also feeds livestock.
Helping to find ways to meet this demand is Prof Matt Clark, a Museum research leader who is studying wheat DNA.
It took over 600 scientists working together to finally sequence the wheat genome in 2018. This was once thought to difficult to do, as the wheat genome is five times bigger than the human one. By understanding and changing wheat genomes, scientists like Matt will help to protect the crop for future generations. Breeders will be able to select traits which will improve wheat harvests and help to secure food stores for billions of people around the world.
Wheat can be bred to withstand severe weather and disease, both of which could become more common as the world warms.
Wheat strains are also being adapted to produce flour with increased iron levels. The ongoing trial, which is being carried out at the John Innes Centre in Norwich, has shown that the new grain contained double the amount of iron compared to a normal grain. This could help to reduce levels of iron deficiency-related anaemia globally. Anaemia is especially common in girls and young women.
Maize, sometimes referred to as corn in the US and Canada, has seen demand surge globally because it is used to feed animals and to create new fuels.
In 2019, researchers in Delaware, USA, successfully increased corn yields by 10% by changing the gene that controls its growth. This modification has proved successful even in poor conditions: plants were given bigger leaves to improve how they turn sunlight into sugar and boost how efficient they are at using nitrogen in the soil.
Genetic modification can have unexpected positive effects, too. Corn which has been engineered to require fewer pesticides may also be safer for humans and animals to eat. That's because corn damaged by insects contains fumonisins - toxins generated by fungi introduced to the corn by insects - which are thought to cause cancer. There is a link between people who eat lots of corn, such as populations in South Africa, China and Italy, and higher rates of oesophageal cancer.
Around 20% of calories consumed across the world come from rice, and it is the main food source for three billion people. Yet the places where rice is most often grown, including areas of India, Bangladesh and China, are constantly at risk of flooding. Rising sea levels and increasingly intense tropical storms mean that this problem is only going to worsen.
One solution to this is scuba rice, which can withstand being soaked in flood water and has been successfully grown in southeast Asia.
Genetic modification can also make rice kinder to nature. Rice paddy fields are a big source of the greenhouse gas methane, but the creation of the SUSIBA2 variety is helping. This rice contains a gene from the barley plant, which can help to reduce methane emissions. A three-year trial showed that this method increased yield by 10% while reducing methane emissions.
The aim of the C4 Rice Project, led by a team from 12 universities across eight countries, is to engineer C4 photosynthesis, meaning to convert the energy from sunlight into rice. C4 photosynthesis is up to 50% more water-efficient than other types of rice and naturally occurs in drought-tolerant or very fast-growing plant species such as bamboo.
The University of Sheffield is one of several institutions working on growing rice with fewer stomata, the tiny openings used for gas exchange. This will result in less water being lost and better performance in exceptionally hot or wet conditions. Results so far show that lower stomatal density means that 60% less water is used. When 4,000 litres of water are needed to grow a kilogram of rice, and rice uses 70% of the agricultural water supply in China, this could be a significant saving.
Dr Haiyan Xiong, a postdoctoral researcher at the University of Cambridge, is working on a similar strategy. Her PhD and postdoctoral work in China focussed on introducing the drought-resistant gene found in upland rice (which grows in dry and hilly conditions) into lowland rice. Lowland rice tends to be better quality but less hardy, so aims to merge the desirable traits of both crops.
So far, Xiong's team has identified three genes which could help make rice more resistant to drought. Her current work at the University of Cambridge is aimed at changing rice plants so they are better at converting the energy from sunlight into food.
Xiong's upbringing in rural Sichuan drew her to a career researching rice. She witnessed drought conditions first-hand, which led to a dream of 'becoming a scientist who can contribute to improving rice resistance to drought stress'. She says, 'Rice is not only one of the most important food crops in the world - it is also a model plant for studying other cereal crops.'
Soya beans are the Americas' most exported crop, making up 82% of its agricultural exports. Around 45% of this soya is crushed to produce oil and meals which are then exported globally. Among these crops are genetically modified soybeans, which have been spliced with the pigeonpea gene to increase resistance to Asian soybean rust (ASR). ASR is caused by a fungus and is one of the most common crop diseases, only treatable by introducing the fungi-resistant trait of other legumes to increase resistance and improve crop yields.
Some people are wary of GM crops, often due to concerns about the cost of seeds, issues surrounding herbicide resistance and worries about allergens and safety. There are also fears that crossing species could inadvertently introduce allergens such as nuts into the food chain. This fear appears unfounded, as to date no adverse reactions have been found in any approved GM products.
Others worry that modified plants could pollinate wild varieties and cause hybrids to pop up. For this to happen, the GM trait would need to be able to survive in the wild, which is not always the case, and GM crops can be designed to be sterile.
In fact, research has shown that there is nothing that differentiates GM crops from naturally occurring ones in terms of health or safety. GM crops can be a force for good by offering an alternative to spraying pesticides that pollute groundwater and can kill surrounding crops.
Globally, GM crop uptake is divided. In some regions, billions of people have eaten GM crops for decades, whereas the European Union is generally resistant to the use of GM foods, though it does import GM animal feed. Many European countries including France, Germany and Croatia have completely banned GM foods. Others such as Spain, the Czech Republic and Portugal grow GM crops.
The USA is one of the widest growers and adopters of GM foods with 60% of processed foods containing ingredients from engineered soy, corn or canola.
What does the future of genetically modified crops hold? The Alliance for Science at Cornell University in the USA is currently working on corn which can resist insects and drought for use in Africa. If farmers plant corn which could do this organically, they could save money on fertiliser and pesticides. Funded by charities including the Bill & Melinda Gates Foundation, it should be available to farmers by 2023.
New gene editing tools such as CRISPR can be used to precision-edit genetic material, even to the level of changing a single base of DNA. This has the potential for enormous worldwide benefits. For this reason the 2020 Nobel Prize in Chemistry was awarded to the discoverers of CRISPR: Profs Emmanuelle Charpentier and Jennifer Doudna.
There is no magic fix to climate change and no sure-fire way to make agriculture more sustainable, but GM crops are helping farmers to adapt to the issues presented by climate change. These crops can result in better yields and survive droughts and floods, helping to make sure there is enough food available for an increasing global population while also reducing the carbon footprint of agriculture.