The green revolution

Hello, I’m professor Sarah Gurr. I hold the chair in food security. Plant diseases threaten our crops and thus diminish the number of calories we harvest. We need to boost productivity, we need to enhance nutritional value, and we need to better protect our crops from disease in order to feed a growing population. Indeed, disease and damage caused by insects, fungi, bacteria, viruses and nematodes lead to the losses of up to 25% of our crops in the field, and up to about 20% losses post harvest. We must face these challenges head on. Modern farming practices stem from the Green Revolution, a series of research and technological developments in the 1950s and ’60s.

The Green Revolution greatly increased global food production through increased mechanization, the introduction of dwarfing varieties, and disease resistant cultivars. But half a century later, our yields have peaked and leveled, and many unforeseen problems have emerged. This is due largely to the practice of growing vast swathes of genetically uniform crops, which we know to be monocultures. Monocultures provide ideal feeding and breeding grounds for crop pests and pathogens, and this has led to one of the major challenges of food security, as new crops, pests and pathogens are emerging to devour our calorie crops. In human health, the biggest challenges are of bacterial and viral infections. But in plant health, it’s the fungal diseases which are problematic.

We currently control fungal infections in two ways. Firstly, by breeding programs to introduce new resistance genes into our crops. Secondly, we spray crops with chemicals that protect plants from disease. Both methods only work for a short time, particularly in monocultures, as new fungal strains emerge that are resistant to the chemicals or which overcome the disease resistance genes that have been bred in. One promising solution is a type of genetic engineering called genome editing. Genome editing allows us to precisely modify DNA in the cell by cutting the DNA sequence using enzymes called nucleases. A good example of where this may help us to meet the challenge of increasing crop yields, improving food nutritional value and combating crop diseases is rice.

Half the world’s population obtaining the bulk of their calories from rice, and we’re going to need about 40% more rice to be grown by 2050 to feed the growing population. Genome editing differs from the earlier technology of genetic modification or genetic engineering, when genes from any organism can be inserted into a crop plant to confer desirable property. A good example of this kind of GM is the so-called Roundup Ready soy bean, which is resistant to the widely used herbicide glyphosate. This means that the farmer could control weeds with herbicide, leaving the soya beans unharmed. Nearly 100 million hectares of Roundup Ready soybeans are planted each year. More than 80% of all soybean production.

Most of these soybeans are used for animal feed. As a result of genome editing, we have discovered how to increase resistance to rice blast, a fungus that destroys up to 30% of the world’s rice crop each year. We’ve also found a way to increase the starch content in rice to improve its nutritional value. And most recently, genome editing has produced improvements in rice growth and productivity. However, these developments are currently just in the laboratory. The next challenge is to test genome editing crop cultivars in the fields.