Rhizobacteria-Mediated Plant Resilience to Abiotic Stresses: Drought, Salinity, and Heat

The frequent occurrence of drought, salinity and heat disasters due to global climate change has become a problem that cannot be ignored and seriously restricts food security and sustainable agricultural development. The role of rhizobacteria in the response of plants to abiotic stress has an important guiding significance in improving plant growth. This paper summarizes the response of plant rhizosphere microbial communities to abiotic stress, analyzes the mechanism by which rhizosphere-related bacteria assist plants to resist abiotic stress, and expounds on the interaction between soil physical and chemical properties, the plant root metabolome, and the rhizosphere microbiome under abiotic stress. This review systematically summarizes the core roles and mechanisms of rhizobacteria in plants' defense against abiotic stress. Stress reshapes the rhizosphere microecology, with drought enriching Firmicutes and Actinobacteria, salt stress increasing Bacteroidetes abundance, and heat stress expanding the dominance of thermotolerant bacteria. Microbial diversity and network structure undergo adaptive reorganization. Streptomyces and Bacillus, as the twin stars aiding plants in enhancing stress resistance, provide medium- to long-term protection through rich secondary metabolites and mycelial networks, while Bacillus achieves acute responses via rapid spore germination, signal induction, and nutrient competition. Rhizobacteria improve soil nutrient availability by regulating carbon, nitrogen, and phosphorus cycles, secreting organic acids and enzymes, and induce plant osmotic adjustment, antioxidant, and anti-ethylene signaling networks through extracellular polysaccharides, volatile organic compounds, plant hormones, and 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase pathways, thereby systematically enhancing the host's water use efficiency and membrane stability. Future research should integrate multi-omics and field validation to precisely construct rhizosphere bacterial communities, providing theoretical basis and technical routes for green agriculture.