As climate change alters rainfall and temperatures, and provokes heat waves and droughts, the quality and quantity of crops suffer. Such changes to yields could significantly jeopardize food security for the world's growing population.
One response is to change which crops are grown where; another is to create more resilient crops. But how far can we push this and with what implications for the human diet?
How bad is the current situation?
There is evidence that some of the great strides to increased crop yields over the last decades are slowing down. "Wheat yields used to increase by an average of 1–1.5 % annually," says Bucher. "This seems to have plateaued, with wheat breeding lines projected to lose almost 4 % of yield for every 1 °C temperature increase."
Climate change increases climate variability, leaving breeders uncertain whether to prioritize tolerance to drought, flooding or disease.
Bucher has investigated ways to build climate resilience into staple crops like rice and wheat, based on how plant genomes rearrange themselves in response to climate-related stressors.
In a study published in Nature Communications, Bucher's team tested the new crop breeding method on wheat, rice and soybean, in simulated conditions of extreme heat and drought. "We got good results for rice and wheat, but soybean remained stubborn. It might work on a wider range of soybean varieties or with different treatments," says Bucher.
But even if these breeding methods prove effective, is there a point where the trade-offs required, for example to taste, make it undesirable?
In classical crop breeding, targeting desired traits reduces overall breeding efficiency. If an elite crop variety is bred with an old variety, to introduce disease resistance for instance, almost all of the elite variety's accumulated gains are lost. Recovery would require years of repeatedly cross-breeding the offspring with elite material.
Consequently, using pre-existing genetic diversity from gene banks is slow and tedious. "Traditional crop breeding is hit and miss. Novel breeding methods, such as ours, accelerate the process, getting a desirable trait from an old variety directly into a new one, without crossing both," explains Bucher.