Genomic characterization of a diazotrophic microbiota associated with maize aerial root mucilage.

Autor: Higdon SM; Department of Plant Sciences, University of California, Davis, California, United States of America., Pozzo T; Department of Plant Sciences, University of California, Davis, California, United States of America., Kong N; Department of Population Health and Reproduction, University of California, Davis, California, United States of America., Huang BC; Department of Population Health and Reproduction, University of California, Davis, California, United States of America.; 100K Pathogen Genome Project, University of California, Davis, California, United States of America., Yang ML; Department of Population Health and Reproduction, University of California, Davis, California, United States of America., Jeannotte R; Department of Population Health and Reproduction, University of California, Davis, California, United States of America., Brown CT; Department of Population Health and Reproduction, University of California, Davis, California, United States of America., Bennett AB; Department of Plant Sciences, University of California, Davis, California, United States of America., Weimer BC; Department of Population Health and Reproduction, University of California, Davis, California, United States of America.; 100K Pathogen Genome Project, University of California, Davis, California, United States of America.
Jazyk: angličtina
Zdroj: PloS one [PLoS One] 2020 Sep 28; Vol. 15 (9), pp. e0239677. Date of Electronic Publication: 2020 Sep 28 (Print Publication: 2020).
DOI: 10.1371/journal.pone.0239677
Abstrakt: A geographically isolated maize landrace cultivated on nitrogen-depleted fields without synthetic fertilizer in the Sierra Mixe region of Oaxaca, Mexico utilizes nitrogen derived from the atmosphere and develops an extensive network of mucilage-secreting aerial roots that harbors a diazotrophic (N2-fixing) microbiota. Targeting these diazotrophs, we selected nearly 600 microbes of a collection obtained from mucilage and confirmed their ability to incorporate heavy nitrogen (15N2) metabolites in vitro. Sequencing their genomes and conducting comparative bioinformatic analyses showed that these genomes had substantial phylogenetic diversity. We examined each diazotroph genome for the presence of nif genes essential to nitrogen fixation (nifHDKENB) and carbohydrate utilization genes relevant to the mucilage polysaccharide digestion. These analyses identified diazotrophs that possessed the canonical nif gene operons, as well as many other operon configurations with concomitant fixation and release of >700 different 15N labeled metabolites. We further demonstrated that many diazotrophs possessed alternative nif gene operons and confirmed their genomic potential to derive chemical energy from mucilage polysaccharide to fuel nitrogen fixation. These results confirm that some diazotrophic bacteria associated with Sierra Mixe maize were capable of incorporating atmospheric nitrogen into their small molecule extracellular metabolites through multiple nif gene configurations while others were able to fix nitrogen without the canonical (nifHDKENB) genes.
Competing Interests: The authors declare no conflicts of interests relevant to this work for employment, consultancy, patents, products in development, or marketed products. None of the authors are employed by the major funding agency of this work, MARS, Inc., but were employed by UC Davis. This does not alter our adherence to PLOS ONE policies on sharing data and materials.
Databáze: MEDLINE
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