Climate Variability Under ENSO Reshapes the Coffea arabica Rhizosphere Microbiome While Preserving a Conserved...

Climate variability is a major driver of belowground microbial assembly, yet its effects on rhizosphere microbiomes in perennial crops remain insufficiently resolved. We investigated how macroclimatic oscillations associated with the El Niño-Southern Oscillation (ENSO) influence bacterial communities in the rhizosphere of Coffea arabica. Using 16S rRNA amplicon sequencing across five sampling campaigns covering El Niño, La Niña, and Neutral phases in the Colombian Andes, together with multivariate and variance-partitioning analyses, we quantified the relative contributions of climatic and edaphic factors to rhizosphere community structure. PERMANOVA across three dissimilarity metrics showed that the ENSO explained 11-17% of β-diversity, exceeding the contribution of intra-annual seasonality (6-12%). Ordination analyses indicated moderate compositional differentiation with considerable overlap among ENSO groups, consistent with gradual community turnover under contrasting hydroclimatic conditions. Rainfall and soil pH emerged as the main edaphic correlates of community composition, although their independent effects were no longer significant after accounting for the ENSO phase and season. Despite these shifts, the rhizosphere remained dominated by Acidobacteriota, Actinobacteriota, and Proteobacteria, and a prevalence-defined core microbiome (genera detected in ≥85% of samples) was maintained across climatic phases and seasons. These results indicate that, within the explained fraction of variation, macroclimatic variability contributed more to rhizosphere bacterial turnover than local edaphic heterogeneity, while a conserved prevalence-defined bacterial core may contribute to taxonomic stability in climate-sensitive coffee systems.