Nitrogen fixation in a landrace of maize is supported by a mucilage-associated diazotrophic microbiota

PLoS Biol. 2018 Aug 7;16(8):e2006352. doi: 10.1371/journal.pbio.2006352. eCollection 2018 Aug.

Abstract

Plants are associated with a complex microbiota that contributes to nutrient acquisition, plant growth, and plant defense. Nitrogen-fixing microbial associations are efficient and well characterized in legumes but are limited in 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 the 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 29%-82% of the nitrogen nutrition of Sierra Mixe maize.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Mexico
  • Microbiota / genetics*
  • Microbiota / physiology
  • Nitrogen / metabolism*
  • Nitrogen Fixation / physiology*
  • Phylogeny
  • Plant Development
  • Plant Mucilage / metabolism
  • Plant Roots / metabolism
  • Polysaccharides / metabolism
  • Soil
  • Soil Microbiology
  • Zea mays / metabolism*

Substances

  • Plant Mucilage
  • Polysaccharides
  • Soil
  • Nitrogen

Associated data

  • figshare/10.6084/m9.figshare.6534545

Grants and funding

Mars, Incorporated http://www.mars.com/global. The research was funded by an unrestricted gift and a grant to ABB. The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. The research was funded by grants to ABB from BioN2, Incorporated. The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Preliminary research was supported by a Dissertation Research Grant from UC Mexus to KS. The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.