Microbial Memory of Drought Reshapes Root-Associated Communities to Enhance Plant Resilience

Global climate change has increased the frequency and severity of droughts, posing significant threats to grassland ecosystems. As a dominant species in meadow steppe in northern China's grasslands, Leymus chinensis exhibits excellent drought resistance, yet the interaction mechanisms between its drought resistance and rhizosphere microbial communities remain unclear. This study simulated short-term drought cycles (0-3) and combined high-throughput sequencing with microbial transplantation experiments to investigate rhizosphere and bulk soil microbial responses to drought and their regulatory effects on host drought resistance. Key findings include: (1) Rhizosphere microbial network connectivity decreased by 63.3% at 3 drought cycles (R3) versus control (R0), while bulk soil only decreased by 11.6%, showing niche-specific adaptation; (2) fungal communities responded rapidly to short-term drought stress, while bacterial (e.g., Proteobacteria) taxa exhibited delayed yet specific recruitment patterns across successive drought cycles, suggesting a time-resolved functional synergy; (3) transplanting R3 rhizosphere soil increased L. chinensis the content of relative water, proline, chlorophyll and soluble sugar, while reducing the relative conductivity and malondialdehyde content, validating the microbial-mediated 'stress memory' effect. These findings reveal that L. chinensis enhances drought adaptation by targeting the recruitment of rhizosphere microbes, providing valuable insights into the ecological resilience and restoration of grasslands.