Foliar pathogen and drought impose reproducible but community-dependent influence on the root microbiome
Plant microbiomes are assembled from environmental pools that differ substantially in composition, yet whether their responses to stress follow general rules or depend on the resident community remains unclear. We tested the generality of root microbiome responses to stress by growing three tomato (Solanum lycopersicum) genotypes in 20 independently sourced microbial communities under controlled…
Plant root microbiomes are shaped by environmental pools with varying compositions, yet the extent to which their responses to stress follow universal rules or depend on the existing community remains uncertain. To examine this, three tomato (Solanum lycopersicum) varieties were cultivated in 20 microbial communities sourced independently under controlled abiotic and biotic stress conditions.
The microbial communities were introduced into a uniform sterile substrate, enabling the manipulation of microbial community identity without affecting soil physicochemical characteristics. The plants were subjected to drought stress, the foliar pathogen Pseudomonas syringae pv. tomato, or no stress. The root microbiota was assessed using 16S rRNA amplicon sequencing.
The identity of the stressor exerted a greater influence on bacterial community composition than the initial inoculum or plant type. Hierarchical models indicated that numerous bacterial taxa exhibited consistent responses across diverse starting communities, with taxon identity contributing far more variation in stress response than the microbial community's origin.
Both stressors transitioned between-community dissimilarity from taxon turnover towards nestedness, suggesting increasingly similar patterns of taxon loss. However, the pathogen generated stronger effects and heightened variability among replicate plants. Drought stress diminished phylogenetic redundancy, while the pathogen intensified dispersal limitation.
Collectively, these findings demonstrate that stressors impose consistent ecological filters across a range of initial microbiomes, although the extent and resulting community state remain dependent on the resident microbial community. This insight offers a foundation for identifying microbial targets applicable across diverse starting microbiomes for microbiome-based crop stress management, while also considering the local microbiome to enhance its beneficial impacts.
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