The world’s bread baskets are heating up, threatening the global food supply. Climate change has already shrunk yields for major crops like wheat and maize, and crop losses are likely to worsen in the coming decades.
But researchers are trying to avoid that future by helping plants deal with heat.
“There’s a lot of excitement in identifying why it is that some crops that are grown in the most extreme conditions are able to survive,” said Carl Bernacchi, a crop researcher at the University of Illinois Urbana-Champaign and the author of one of a trio of papers on crop modification that were published Thursday in the journal Science.
Farmers can help crops beat the heat with water-based cooling, but that method has limitations. Modifying crops, either through traditional crossbreeding, artificially sped-up mutation or direct genetic editing, offers control over how plants respond to heat.
Photosynthesis, the process through which plants get energy, grinds to a halt between 40 and 45 degrees Celsius, or 104 to 113 degrees Fahrenheit, temperatures that are becoming more common in many of the world’s agricultural regions.
“Photosynthesis really dictates the currency plants have to use,” Dr. Bernacchi said. “If photosynthesis falters, plants run out of energy and die.”
Dr. Bernacchi and his co-authors reviewed the potential of editing rubisco, the key enzyme that transforms carbon into sugar, and its partner, rubisco activase. In plants that grow in warm climates, rubisco activase seems to work better at helping rubisco function. Transferring that molecule from hot-climate plants to cool-climate plants can help cool-climate plants adapt to heat. Simply boosting its activity could help, too.
Altering photosynthesis is still a distant goal, said Walid Sadok, a crop physiologist at the University of Minnesota who was not involved with the paper.
“It’s a complex endeavor,” he said. “It’s still in its infancy, but it’s an interesting idea.”
A plant’s genome can also be altered to change its leaf architecture, spacing leaves out and setting them at just the right angle to ensure a balance of sun and shade that can help maintain temperature and productivity. Editing a leaf’s reflectivity and the amount of chlorophyll, or green pigment, that it contains can help, too.
Plants’ temperature-sensing system could also be modified. In a second Science paper, researchers propose a new way of understanding the network of proteins that control plants’ responses to heat. Instead of plants having discrete “thermometers,” temperature sensing could be spread out in many plant systems and proteins, the researchers say. That could provide many targets for editing for heat tolerance.
“We could develop designer crops tailored to future climates,” said Suresh Balasubramanian, a plant geneticist at Monash University in Australia who led the study.
Selective crossbreeding of plants is still a reliable option and should be continued while researchers work toward more complicated genetic editing goals, Dr. Sadok said.
But as temperatures climb beyond levels that modern crops can withstand, genetic editing may be more crucial, Dr. Bernacchi said.
“We may get to a point where existing crops don’t have the genetic diversity we need to adapt crops to the growth conditions that we’re going to see in the near future,” he said. “In that situation, we might need to be creative.”
Wild plants hold a vast pool of genetic diversity that could inspire new ways to keep crops cool. Plants can thrive in the hottest and driest places on Earth, such as Death Valley in California, the Atacama Desert in South America and the Namib Desert in southern Africa, where temperatures regularly soar above the threshold for photosynthesis.
Exploring these plants’ genomes could give scientists genes to transfer into staple crops such as soybeans, wheat and rice, bringing along heat tolerance. Scientists can also work backward, starting with a highly heat-tolerant plant and using genetic editing to add other desirable traits, like taste and size.
“We’re trying to cast our net more broadly,” said Sam Yeaman, an evolutionary biologist at the University of Calgary who wrote a third paper. “If we limit ourselves to only looking at crops, we’re going to have a tiny slice of the picture.”
Some complex genetic editing projects, such as photosynthesis or the temperature-sensing system, are years away from hitting farmers’ fields. Other genetic editing tools for heat tolerance, like changes to leaf architecture, could be available sooner, if they could get field tested and permitted, an expensive and time-consuming process.
“Funding right now in the United States doesn’t look particularly promising for the future of this research,” Dr. Bernacchi said.
And acceptance of genetically modified foods has been shrinking over the past decade or so, said Dominique Brossard, who studies the communication of controversial topics at the University of Wisconsin. The Trump administration’s movement toward “natural” foods could further stymie willingness to adopt genetically modified foods, she said.
The post Soaring Temperatures Threaten Crops, So Scientists Are Looking to Alter the Plants appeared first on New York Times.
