Soil and water

Husker scientist leads efforts to understand and adapt nitrogen conversion in legumes | Nebraska today

Soybeans and other legumes interact with nitrogen-fixing soil bacteria called rhizobia which are able to convert nitrogen from the air into a form the plant can use to grow and reproduce. Corn and other crops cannot, requiring nitrogen fertilizers to maximize growth and yield – problematic because overapplication or runoff can pollute soil and water.

Researchers are trying to find alternative and sustainable sources of nitrogen to solve this problem.

“Can we transfer this ability to non-legumes?” ”Asked Marc Libault, a plant scientist at the University of Nebraska-Lincoln.

Libault is leading a multi-agency research team seeking to better understand how legumes partner so productively with a group of bacteria called rhizobia, which convert atmospheric nitrogen into a chemical form that supports the host plant.

“This biological process, called nodulation, is economically important and benefits agricultural sustainability and food security,” said Libault, associate professor of agronomy and horticulture.

It begins with the infection of the root hair cell of the plant by rhizobia. Although this type of cell is found in almost all flowering plants, the root hair cell is only able to initiate this symbiotic relationship in a subset of plants, one of which is legumes.

“Although several legume genes involved in this process have been characterized, a better understanding of the genetic programs controlling root hair infection by rhizobia is needed before considering the transfer of nodulating capacity to non-legume crops.” , said Libault.

In addition to soybeans, researchers will study medicago, a genus of flowering plants that includes alfalfa and common bean.

Libault’s team will characterize these genetic programs using unicellular plant technologies. In addition to its impact on scientists’ understanding of legume nodulation and biological nitrogen fixation, this project will promote integration between research and teaching by supporting the development of STEM educational programs for high school and undergraduate students.

Ultimately, researchers might be able to genetically modify non-legumes such as corn, rice, and wheat to give them the ability to attract rhizobia and fix atmospheric nitrogen. Using less fertilizer could not only reduce pollution, but also significantly reduce input costs for farmers.

Libault said the project is based on the assumption that the differentiation of plant cells, the gain of biological functions and the response to external stimuli are controlled by transcriptional modules conserved during evolution. Working on three species of legumes will reveal these modules.

Researchers will analyze the molecular mechanisms associated with the early stages of the nodulation process by studying the biology of hair cells isolated from the roots of legumes one by one. Access to changes in gene activity and chromatin accessibility profiles will provide insight into the dynamic response of a plant cell to microbial infection and the level of conservation of these responses among legume species. and during the duplication of the entire genome.

The University of Nebraska-Lincoln has made research on sustainable food and water security one of its major challenges. It was designated as a priority because of the university’s expertise in this area and the impact that Husker research can have on more sustainable agricultural production.

Libault, who is affiliated with the Nebraska Center for Plant Science Innovation, works with colleagues from Cornell University, University of Michigan, Reed College, and the National Center for Genome Resources. The work is funded by a $ 1.5 million grant from the National Science Foundation.

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