Lunchtime Lecture Series: “Nitrogen fixation in maize landraces from Oaxaca, Mexico”

Presented by: Dr. Jean-Michel Ané, Professor in the Bacteriology and Agronomy departments at the University of Wisconsin - Madison (agronomy.wisc.edu/jean-michel...)
About the presentation: Plants are associated with a complex microbiome that contributes to growth, nutrient acquisition, and defenses. Nitrogen-fixing microbial associations are well-characterized in legumes but are mostly absent from cereal crops, including maize.
We studied an Indigenous maize landrace grown without using nitrogen fertilizers in the nitrogen depleted soils of Totontepec Villa de Morelos in Oaxaca, Mexico. This landrace is characterized by the extensive development of aerial roots that secrete a sugar-rich mucilage (gel) after rain. These landraces are also very tall and grow over 9-10 months. The mucilage is enriched in nitrogen-fixing bacteria and supports an intense nitrogen fixation activity. Field and greenhouse experiments in Totontepec Villa de Morelos and Wisconsin, using two different assessments (15N natural abundance and 15N-dilution assessments), over five years, demonstrated that plants were acquiring half of their nitrogen from the air.
In collaboration with the Centro Internacional de Mejoramiento de Maiz y Trigo -CIMMYT-, we identified several maize landraces from other locations throughout Oaxaca that present the same characteristics. We also found the trait in some teosinte species, the progenitor of domesticated maize. We are currently studying the plant and bacterial genes controlling nitrogen fixation on aerial roots, evaluating the trait’s environmental limits, its impact on yield, and its evolution. To make this nitrogen fixation available to a wide range of maize growers in developed and developing countries, we have started introducing the trait into maize varieties with a more standard size and growth features. We are also exploring avenues for traditional growers to breed for nitrogen-fixation locally using this knowledge and tools that we are developing.
Presented February 9, 2021.
Programming provided by the Latin American, Caribbean & Iberian Studies Program at the University of Wisconsin-Madison.