Nitrogen fixing in corn
2019
- UW-Madison
Project Media
Plants are associated with a complex microbiota that contributes to nutrient
acquisition, plant growth, and plant defense. Nitrogen-fixing microbial associations
are well characterized in legumes but are largely absent from cereals, including
maize. We studied an indigenous landrace of maize grown in nitrogen depleted soils
in the Sierra Mixe region of Oaxaca, Mexico. This landrace is characterized by
extensive development of aerial roots that secrete a carbohydrate-rich mucilage.
Analysis of the mucilage microbiota indicated that it was enriched in taxa for which
many known species are diazotrophic; was enriched for homologs of genes encoding
nitrogenase subunits; and harbored active nitrogenase activity as assessed by
acetylene reduction and 15N2 incorporation assays. Field experiments in Sierra MIxe
using 15N natural abundance or 15N-enrichment assessments over 5 years indicated
that atmospheric nitrogen fixation contributed 30 to 82% of the nitrogen nutrition of
Sierra MIxe maize.
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