Research Highlights

Breeding Soybean Plants That Lock in Moisture

By Sarah Hill

What if growers could protect their soybean crop from severe drought stress and rescue some of the lost yield? As drought conditions become increasingly more common in areas where soybeans are grown, soybeans that can withstand lower moisture levels would be a game changer for many soybean growers. These resilient varieties would improve soybean growth and yields in dry years, putting more money in their pockets at harvest.

Drought Conditions May Worsen

“When seeds are setting is when crops such as rice, corn and soybean are very susceptible to a lack of water,” says Katarzyna Glowacka, assistant professor of biochemistry at the University of Nebraska. “That can result in 30% of yield being lost, depending on the severity of the drought.”

In Nebraska, around half of all soybeans are irrigated, especially in the western part of the state, adding up to about 2.8 million acres. Another 2.9 million acres are watered only through rainfall. Drought conditions are predicted to be more severe in the near future, Glowacka says.

Her research team, funded by the Nebraska Soybean Board, is exploring how to utilize genetic modification to target a naturally occurring protein that can make soybeans more efficient with water use. The transgenic soybeans currently studied by Glowacka’s team produce more of this protein than conventional cultivars. 

“We want the soybean plant to only turn on this modification when the plant is exposed to drought, heat stress, or if there is simply less water available in the soil,” she says. “We’re not introducing anything new into the soybean genome but helping soybeans to benefit from less stress.”

Tricking Plants into Losing Less Water

All plants, including soybeans, produce sugars and energy through photosynthesis, the process of absorbing sunlight and carbon dioxide. Plants have small pores in their leaves called stomatal pores that open to let in carbon dioxide. The pores close at night, holding in moisture.

“The wider those stomatal pores open, the more water is lost,” Glowacka says. “When plants experience lower sunlight conditions, they send a signal to the stomatal pores to close, but not completely shut.”

Not much is known about the signal and how it works in soybean plants, but Glowacka says that it is influenced by the light condition that plants detect in their environment. She also notes that it originates in the chloroplasts. 

The genetic modification Glowacka’s team is testing will trick the soybean plant into thinking the weather is cloudier than it really is, so the soybean plants will close their stomatal pores and retain more moisture. Glowacka notes that the soybeans will still be able to perform photosynthesis in this condition, and their capability to produce energy will not be stunted in any way. 

A similar type of genetic modification in tobacco plants led to a 25% reduction in the amount of water used for each molecule of carbon dioxide assimilated by the plant leaves. 

“Under the drought conditions last year in a small field, our preliminary data has shown that when plants experience high light and drought stress, this genetic modification helps plants to grow better and, in the end, produce more seeds,” Glowacka says. “This year, we will be testing it on a bigger scale.” 

As a next step, Glowacka’s team will analyze the nutritional content of the soybeans to compare it to unmodified soybeans. She also hopes to find other genes that can help make soybean plants more water efficient and stack those genes together for increased benefit.

“We’ve already seen big advances in yield thanks to the green revolution,” Glowacka says. “To produce enough food for the growing global population, we’re going to have to find new approaches.”

With that in mind, Glowacka’s team is examining what other improvements can be made to soybean plants to continue improving yield. They aim to provide stable yields while offering farmers an insurance policy in the form of these genetically modified plants that can better withstand drought. 

Published: Jun 5, 2023