Nitrogen fixation in a landrace of maize is supported by a mucilage-associated diazotrophic microbiota
Fig 3
DNA sequencing–based characterization of the microbiome of Sierra Mixe maize.
(A) Samples clustered by PCoA on Bray-Curtis dissimilarity distance matrix. Bacterial communities were assessed using PCR amplification and sequencing of rRNA genes. Each point corresponds to an individual sample. Permanova tests run using adonis in vegan revealed mucilage samples were statistically distinct (e.g., mucilage versus rhizosphere P = 0.002, mucilage versus roots P = 0.03, mucilage versus aerial roots P = 0.03). (B) Metagenomic sequencing–based analysis of homologs of core nif genes (nifH, nifD, nifE, nifK, nifN, and nifB) and alternate nitrogenase (anfG/vnfG). Metagenomic samples were searched for homologs by mapping reads on reference nif trees. The number of hits was normalized to an estimate of the number of bacterial genes in the metagenomic sample (measured using the number of hits to the RecA hidden Markov model). *The lowest abundance of a core nif gene in mucilage and rhizosphere libraries. **Only core nif gene hit in stem library. anfG and vnfG alternate nitrogenase were observed only in mucilage library. PCoA, principal component analysis.