Summary Rhizomicrobiome plays important roles in plant growth and health, contributing to the sustainable development of agriculture. Plants recruit and assemble the rhizomicrobiome to satisfy their functional requirements, which is widely recognized as the ‘cry for help’ theory, but the intrinsic mechanisms are still limited. In this study, we revealed a novel mechanism by which plants reprogram the functional expression of inhabited rhizobacteria, in addition to the de novo recruitment of soil microbes, to satisfy different functional requirements as plants grow. This might be an efficient and low‐cost strategy and a substantial extension to the rhizomicrobiome recruitment theory. We found that the plant regulated the sequential expression of genes related to biocontrol and plant growth promotion in two well‐studied rhizobacteria Bacillus velezensis SQR9 and Pseudomonas protegens CHA0 through root exudate succession across the plant developmental stages. Sixteen key chemicals in root exudates were identified to significantly regulate the rhizobacterial functional gene expression by high‐throughput qPCR. This study not only deepens our understanding of the interaction between the plant–rhizosphere microbiome, but also provides a novel strategy to regulate and balance the different functional expression of the rhizomicrobiome to improve plant health and growth.

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[Objective] Determine the ability of three plant growth promoting rhizobacteria (PGPR) strains (Pseudomonas Mandelli A36, Serratia plymuthica A13 and Pseudomonas koreensis A20) to promote plant growth, evaluate the effect of inoculation with PGPR strains on seedling biomass, root structure, nutrient index, and enzyme activity, and assess the effect of PGPR inoculation on soil nutrient index, enzyme activity, and the soil microecological environment.[Method] The ability of the three PGPR strains to secrete indole-3-acetic acid (IAA), dissolve inorganic phosphorus, and produce siderophore and hydrolase was determined by the medium color change method, pot experiment to determine the effects of three PGPR strains on plant biomass, physicochemical properties, soil physicochemical properties and microbial diversity. [Result] The three PGPR strains had the ability to secrete IAA, solubilize inorganic phosphorus, and produce siderophore, the results of the pot experiment showed that inoculation with PGPR strain had a significant effect on plant biomass, root index, nutrient index and enzyme activity, as well as soil nutrient index, enzyme activity and bacterial diversity. [Conclusion] This study provides basic data references for PGPR strains to improve the soil microecological environment and promote the growth and development of Pinus sylvestris var. Mongolica seedlings.