How crops are being disaster-proofed

Late blight is an old foe of humans. This disease catalysed the devastating Irish potato famine that began in 1845.
It is caused by a fungus-like pathogen, which quickly kills a potato plant and turns the crop into inedible mush.
More recently, late blight has been creeping into higher parts of the Peruvian Andes, as warmer, wetter weather helps the pathogen spread.
So scientists at the International Potato Center (CIP), a research institute in Peru, were very motivated to develop potato varieties that could resist late blight.
They searched for this trait among so-called crop wild relatives – undomesticated plants that are distantly related to the ones now grown for food.
After finding the disease resistance in potato wild relatives, they crossed the wild plants with cultivated ones. Local farmers then tested the newly developed varieties, voting for the ones they preferred to grow, sell and eat.
The result is CIP-Matilde, a potato variety released in 2021 that doesn’t require fungicides to stand up to late blight.
“Usually it’s easier to improve the resistance to a certain disease,” explains Benjamin Kilian, a senior scientist at the Crop Trust, based in Bonn, Germany. The non-profit organisation partnered with CIP to develop the Matilde potato, and is working on many other crop varieties.
While disease resistance might come down to a single gene, making resistance to stressors like drought or salinity, can involve working with hundreds of genes.
To tackle drought tolerance, for instance, scientists could explore traits like early flowering to escape the effects of drought, less loss of water from plant leaves, or long roots so that plants can extend further to reach water.
Mr Kilian leads the Crop Trust’s Biodiversity for Opportunities, Livelihoods and Development (Bold) project, which brings together partners including community seed banks, national breeding programmes, and international research centres.
Crucially, it also convenes farmers. They express their preferences for particular traits and test the different crop varieties under development (including voting by placing stones, sticks or seeds next to their favourite varieties).
These participatory processes involve listening to different kinds of farmers, Mr Kilian says.
For instance, “sometimes women and men, even within the same family, prefer different traits.” Women might be more concerned about taste and nutrition, while men are often more focused on yield.
Yield – the amount of a crop actually harvested per unit of land – is never too far from conversations around agricultural production. However, attempting to maximise yield at all costs has led to a more monotonous food system, with high-yield varieties displacing a range of others.
“Under optimal conditions with high input you can achieve great yields. But you can also risk complete crop failure,” Mr Kilian says.
“For most farmers, it’s more important to have a stable, reliable yield under all kinds of different environments.”
One crop that the Bold project is supporting is the grass pea. Mr Kilian explains that this nutritious legume can handle waterlogging and tough environments. “It was often the last crop that survived if there was a drought event.”
It fell out of favour because of a toxic compound that could be dangerous if eaten in large quantities (such as during a famine). But the Crop Trust and partners are working to reduce the toxicity by cross-breeding grass peas with crop wild relatives.
Another neglected crop that scientists are heralding for its resilience is azolla, a fern that grows astonishingly quickly and doesn’t require much water. The wild tepary bean, meanwhile, can withstand harsh desert conditions.
By Christine Ro