Of all the world’s staple foods, perhaps none is as ubiquitous as corn.
Each person on Earth eats an average of 70 pounds of the grain each year, and even more is grown for animal feed and biofuel. And as the global population continues to grow, increasing the amount of food produced on the same amount of land becomes increasingly important.
One potential solution: Develop crops that perform better in cold temperatures. Corn is a tropical plant, making it extremely sensitive to cold weather. This is problematic in temperate climates, such as upstate New York, where the growing season averages four to five months – and where more than 60% of its 1.6 trillion-pound annual production occurs.
A chilling-tolerant strain could increase the area in which the crop can be grown, and increase current productivity.
A group of researchers led by David Stern, president of the Boyce Thompson Institute, has moved closer to this goal by developing a type of corn that recovers much more quickly after a cold snap.
Their paper, “Increased Rubisco Content in Maize Mitigates Chilling Stress and Speeds Recovery,” published Dec. 20 in Plant Biotechnology Journal.
“In the field, chilling stress happens most often in the spring when cold temperatures combine with strong sunlight, causing plants to bleach,” said Stern, also an adjunct professor of plant biology in the College of Agriculture and Life Sciences. “So a more chilling-tolerant corn could help farmers plant earlier in the year with confidence that their crop would survive a cold spell.”
This work built on research published in 2018, which showed that increasing levels of an enzyme called Rubisco led to bigger and faster-maturing plants. Rubisco is essential for plants to turn atmospheric carbon dioxide into sugar, and its levels in corn leaves decrease dramatically in cold weather.
In the latest study, Stern and colleagues grew corn plants for three weeks at 77 degrees F, lowered the temperature to 57 F for two weeks, then raised it back to 77 F.
“The corn with more Rubisco performed better than regular corn before, during and after chilling,” said Coralie Salesse-Smith, Ph.D. ’18, the paper’s first author and former member of Stern’s lab. “In essence, we were able to reduce the severity of chilling stress and allow for a more rapid recovery.”
Indeed, compared to regular corn, the engineered corn had higher photosynthesis rates throughout the experiment, and recovered more quickly from the chilling stress with less damage to the molecules that perform the light-dependent reactions of photosynthesis.
The end result: a plant that grew taller and developed mature ears of corn more quickly following a cold spell.
Sweet corn is a major vegetable crop in New York state, worth about $40 million to $60 million annually. According to horticulture professor Steve Reiners, co-team lead for Cornell Cooperative Extension’s vegetable program, many New York corn growers plant as soon as they can because an early crop commands the highest prices of the season.
“Many corn growers in New York plant early under protective plastic sheets to increase soil temperatures, which is expensive,” said Reiners, who was not involved in the study. “Chilling-tolerant corn could allow farmers to remove that plastic sooner. This would expose the plants to additional sunlight, potentially enabling them to mature earlier in the season.”
Stern said the corn they developed isn’t yet optimized for chilling tolerance, and more modifications are in the works. The researchers believe their approach could also be used in other crops, such as sugar cane and sorghum, that fix carbon in the same way as corn.
Researchers from The Australian National University in Canberra contributed to the study, which was supported by grants from the U.S. Department of Agriculture’s National Institute of Food and Agriculture and from the Australian Research Council.
Aaron J. Bouchie is a science writer at Boyce Thompson Institute.