# Stress-induced keystone species facilitate functional microbial community assembly to suppress root-knot nematodes for susceptible plants

## TL;DR

Stress from nematode infection leads to the recruitment of a key bacterial species that helps build a microbial community to protect plants.

## Contribution

Identification of a keystone bacterial strain that drives functional microbial community assembly to suppress nematodes.

## Key findings

- RKN infection restructured the rhizosphere bacterial community in susceptible cucumber plants.
- The Rhizobium pusense strain TYQ1 inhibited RKNs and restructured the microbial community.
- A TYQ1-centered synthetic community showed efficient and stable nematode suppression.

## Abstract

Stresses (e.g. high temperature, drought, and pests) can reshape the structure of root-associated microbial communities, but how to discover functional microbial community assembly to support plant health remains a great challenge. Here, we found that root-knot nematode (RKN) infection restructured the rhizosphere bacterial community in RKN-susceptible cucumber plants, regardless of the soil type. We isolated a Rhizobium pusense strain, TYQ1, which was significantly enriched following RKN infection. This strain not only directly inhibited RKNs but also caused the restructuring of the rhizobacterial community, thereby leading to the enrichment of multiple biomarker species. These enriched microorganisms, in collaboration with TYQ1, enhanced the biofilm-forming ability of the community and established a tightly interconnected metabolic interaction network, further strengthening the colonization of TYQ1 in the rhizosphere. Ultimately, the TYQ1-centered synthetic community exhibited more efficient and stable inhibition of RKNs. These findings highlight that stress-induced recruitment of keystone species can guide functional microbial community assembly to synergistically enhance plant health.