Drought reduces root microbial diversity and alters the composition in Populus trees, notably increasing Actinobacteria, Firmicutes, and Proteobacteria. Beneficial microbes, including Streptomyces rochei and Bacillus arbutinivorans, were isolated from drought-stressed rhizosphere soils. Controlled inoculation with these microbes enhanced plant growth and drought tolerance, highlighting root microbiome manipulation as a strategy to improve stress resilience.