Pathogen invasion enhances the abundance of predatory protists and their
prey associations in the plant microbiome
Abstract
Untangling the responses of protistan communities associated with soil
and plant compartments and their associations with bacterial and fungal
communities to pathogen invasion are critical for understanding the
ecological processes governing plant microbiome assembly. Here we
examined the protistan communities across the soil–plant continuum of
healthy chili peppers and those with Fusarium wilt disease (FWD) and
integrated the bacterial and fungal microbiome data from our previous
investigation in China. We found that FWD was associated with a
significant enrichment of phagotrophic protists in roots and an increase
in the proportion and connectivity of these phagotrophic protists in
intra- and interkingdom networks. Specifically, FWD increased the
negative correlations between phagotrophic protists (especially Cercozoa
and Ciliophora) and several members of Actinobacteria,
Alphaproteobacteria, and Gammaproteobacteria in the interkingdom
networks. Furthermore, the microbiomes of diseased plants not only
exhibit a higher relative abundance of functional genes related to
bacterial anti-predator responses compared to healthy plants, but also
contained a greater abundance of metagenome-assembled genomes possessing
functional traits involved in this response. The increased microbial
interkingdom correlations among bacteria, fungi, and protists, coupled
with the enhanced effects of protists on bacteria and fungi, as well as
the notable bacterial anti-predator feedback in the diseased plant
microbiome, all suggest that FWD catalyzes the associations between
different groups of microbiomes. These findings highlight the role of
predatory protists in shaping microbial assembly and functionality
through top-down forces during pathogenic stress, potentially
contributing to co-evolution within these soil and plant microbiomes.