Potential diazotroph communities of Cordia dodecandra phyllosphere endophytes in agroforestry systems

Background: Endophytic bacteria in the phyllosphere play a crucial role in plant growth and health. The microbiota of Cordia dodecandra, a Mesoamerican native species, may include diazotrophic bacteria. Questions: This study evaluates changes in the phyllosphere microbiota of C. dodecandra growing in two agroforestry systems and explores its potential for nitrogen fixation. Studied Species / Data Description: A metagenomic approach was used to analyze next-generation sequencing data from foliar DNA of C. dodecandra. Study Site and Dates: Samples were collected in July 2023 from six trees located in two agroforestry systems at Rancho Juanes, Yucatán. Methods: Tree dasometric variables and foliar nutrient contents were recorded. Diversity of endophytic bacteria was analyzed using 16S rRNA V3–V4 sequences. Potential diazotrophs were identified based on nifH gene sequences. Correlation analyses were performed between nifH abundance (estimated via qPCR), tree traits, and foliar nutrients to assess the influence of potential diazotrophic activity on tree growth. Results: Dasometric measurements and foliar ammonium content varied notably among the six trees, while foliar nitrogen and carbon were relatively similar. A total of 420 ASVs were identified as endophytes, with nine dominant genera consistently found across all samples. nifH sequences were assigned to six putative diazotrophic species. A marginal positive correlation was found between nifH abundance and canopy cover. Conclusions: The core endophytic microbiota of the C. dodecandra phyllosphere may contribute to tree growth and show diazotrophic potential. Further research is needed to understand the ecological functions of bacterial endophytes in tropical trees.