Certain Tomato Root Exudates Induced by Pseudomonas stutzeri NRCB010 Enhance Its Rhizosphere Colonization Capability

Plant growth-promoting rhizobacteria (PGPR) can colonize plant root surfaces or form biofilms to promote plant growth and enhance plant resistance to harsh external environments. However, plant-PGPR interactions, especially chemical signaling molecules, are poorly understood. This study aimed to gain an in-depth understanding of the rhizosphere interaction mechanisms between PGPR and tomato plants. This study found that inoculation with a certain concentration of Pseudomonas stutzeri significantly promoted tomato growth and induced significant changes in tomato root exudates. Furthermore, the root exudates significantly induced NRCB010 growth, swarming motility, and biofilm formation. In addition, the composition of the root exudates was analyzed, and four metabolites (methyl hexadecanoate, methyl stearate, 2,4-di-tert-butylphenol, and n-hexadecanoic acid) significantly related to the chemotaxis and biofilm formation of NRCB010 were screened. Further assessment showed that these metabolites positively affected the growth, swarming motility, chemotaxis, or biofilm formation of strain NRCB010. Among these, n-hexadecanoic acid induced the most remarkable growth, chemotactic response, biofilm formation, and rhizosphere colonization. This study will help develop effective PGPR-based bioformulations to improve PGPR colonization and crop yields.