A new way of growing crops in marginal soils could help feed the world

The world's population is expected to reach 9.7 billion in 2050 – but how are we going to feed all these people? About one-third of the world's arable land suffers from a lack of accessible iron, which makes it inhospitable for staple crops such as corn and soybeans.

Last year, a Stanford research team led by Elizabeth Sattely, an associate professor in chemical engineering, discovered a genetic adaptation that allows a robust plant to thrive on these marginal soils. Now his laboratory has revealed more about the genetic mechanisms underlying this survival trait. Although further studies are needed, Dr. Sattely believes that this research path will one day allow scientists to integrate this adaptation mechanism into the genomes of staple crops, thereby opening up more farmland. to food production and leading to a new form of plant genetics that is respectful of the environment. engineering. "We may be able to take the traits developed by natural selection and move them where we need them," says Sattely.

Sattely's lab is studying soil microbiomes – the community of bacteria that live around plants to help treat nutrients in the same way that intestinal bacteria help people digest food. His research in this area focuses on a form of plant indigestion: the inability to absorb enough iron, which hinders crop growth and decreases yields.

Scientists have known for a long time why such iron deficiencies occur. Many arid regions of the world, including the western United States, have alkaline soils, and this alkalinity acts as a chemical lock that traps iron in the soil. But after studying this problem for years, Sattely's lab discovered how a plant called Arabidopsis thaliana, parent of cabbage and mustard, overcomes this iron deficiency thanks to the way its roots interact with alkaline soils. The researchers showed how Arabidopsis the roots secrete a molecule of the coumarin family that exerts a chemical pull that helps extract the iron in the plant, overcoming the compensatory tugging of the soil alkalinity.

In their most recent experiments, Sattely's lab discovered another way that coumarin can help Arabidopsis acclimatize to alkaline conditions: coumarin molecules that the plant's roots secrete into the soil drive out certain bacteria. Since bacteria also need iron to grow, the researchers assume that the plant is trying to protect its access to a vital mineral. "Arabidopsis has developed a metabolic pathway that chemically alters the surrounding soil and its root microbiome when its iron intake is limited," said Mathias Voges, a graduate student at Sattely's laboratory who led this new work.

To study all these chemical interactions, which usually occur underground and out of sight, Sattely's laboratory has developed an experimental process based on hydroponics. Voges grew up Arabidopsis plants in water with a chemical and mineral content similar to that of alkaline soils. In this environment, he added the different types of bacteria that normally make up the Arabidopsis root microbiome. In the future, researchers will be able to use this hydroponic platform to create different pseudo-soil environments to test the plant's response to other adversities. For example, can plants adjust their microbiome to improve the absorption of minerals in soils deprived of nitrogen?

In the short term, Sattely's lab will attempt to better understand the functioning of coumarin adaptation, so that it can eventually process wheat, corn or other crops into engineering. biological in alkaline soils. Meanwhile, while researchers are using the hydroponics technique to discover other adaptations of root microbiome, she thinks it will lead to a second generation of plant genetic engineering. Instead of transforming plants into artificial characters, scientists will acquire the ability to transfer naturally evolved characters from one plant to another.

"We envision a new kind of environmentally friendly crop science," Sattely said.