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USC College Biologists Awarded $3.2 Million NSF Grant

A small North-African legume may contribute to sustainable agriculture.

USC College Biologists Awarded $3.2 Million NSF Grant

Scientists and other experts warn that we can expect a global food crisis in approximately 20 years. If we have learned anything from the series of world energy crises since 1973, it is the need to take a proactive approach to global resource challenges. According to current estimates one-fifth to one-third of irrigated land is at risk of salinization, which refers to an increase in soil salt levels due to irrigation. Deteriorating soil fertility and the dependence on fossil fuel-derived fertilizers is another threat.

For the first time, USC has received a Plant Genome Research Grant from the National Science Foundation. By focusing on a small plant that can improve soil fertility naturally, even under saline conditions, Sergey Nuzhdin, professor of molecular biology in USC College of Letters, Arts & Sciences, and his fellow researchers hope to improve the world food shortage problem.

The grant will fund a three-year study on adaptation to saline soil in the legume Medicago truncatula (Mtr). This species is a genetic model for important crop legumes, such as soybean, alfalfa, pea, bean, and peanut. The study involves a cross-cultural exchange with Tunisia and France. Nuzhdin, principal investigator and project director, will travel between these countries with graduate and top undergraduate students to conduct the joint research.

Nitrogen, which makes up 80 percent of our atmosphere, is the main component of soil fertility. Plants can’t access this abundant resource on their own. Legumes are a special family of plants that form symbioses with bacteria called rhizobia, which convert nitrogen gas into ammonia that plants can use.

Legumes are the cornerstone of sustainable agriculture because of this unique ability, and are second only to grasses (cereals) in providing food crops. They are also a major component of global human nutrition, providing an essential amino acid found only in meat and legumes. In fact, legumes are the main protein source of the majority of low-income households worldwide.

Medicago truncatula grows around the Mediterranean Basin. Populations that grow naturally both on and off saline soils in Tunisia will form the basis of the investigation. Located in Northern Africa, Tunisia is an arid region with many naturally saline soils. Since these soils have been salty for millennia, wild plants have had enough time to adapt. By studying these populations, Nuzhdin and his team of researchers at USC and UC Davis hope to acquire a better understanding of the genes underlying the unique ability of these model plants to grow in saline soil.

“Soil salinization is a problem in many parts of the world, including Australia, Kazahstan, and California,” Nuzhdin said. “And accordingly, our efforts will pay off both locally and globally.”

Maren Friesen, a USC College postdoctoral researcher, will conduct genomic analysis and coordinate field tests in Tunisia to evaluate the genetic basis of how soil salinity impacts legume growth. Medicago truncatula can be used in place of fertilizer for optimal crop rotation and production. In addition, the genetic knowledge gained can be used to improve other legumes, Friesen pointed out. She worked with lab strains of Medicago and its partner rhizobia during her doctoral studies at UC Davis.

This amazing opportunity will enable Friesen to interact with world leaders in legume-microbe interactions. “Close collaboration with scientists in France and Tunisia will provide me with international experience to lay the groundwork for expanded ecological and evolutionary research on Medicago species throughout the Mediterranean,” Friesen said.

The complexity of biology has always fascinated Friesen, who double majored in mathematics and biology as an undergraduate. “I am drawn to biology by its direct application to our lives—our conscious interaction with the world is on a biological scale, though driven by chemical, physical and ultimately mathematical processes,” Friesen said. “Our project also integrates the fields of genetics and ecology.”

The work of Nuzhdin’s research team will ultimately produce a better understanding of genomics in both natural and agricultural ecosystems. By linking genes to the performance of this small legume in different environments, they will make an important step toward understanding how communities of plants and microbes function together.

For more information on this project, visit our website