The histidine kinase PhpA regulates the biocontrol activity of Pseudomonas bijieensis 2P24 through the Gac/Rsm signaling pathway

BACKGROUND

Histidine kinases in rhizosphere bacteria regulate physiological behaviors through two-component systems (TCSs) in response to environmental cues. The RetS-GacS/GacA multikinase network is critical for 2,4-diacetylphloroglucinol (2,4-DAPG) production and biocontrol activity in Pseudomonas bijieensis 2P24. However, the involvement of additional histidine kinases in this regulatory pathway remains unclear.

RESULTS

Genetic assay showed a mutation in phpA significantly reduced the expression of small non-coding RNAs RsmY and RsmZ, thereby attenuating the expression of phlA and diminishing 2,4-DAPG production of strain 2P24. Bacterial two-hybrid assay demonstrated that PhpA interacted with RetS and GacS to influence the function of RetS and GacS. Additionally, PhpA modulated diverse cellular processes, including environmental information processes, genetic information processes, and secondary metabolism.

CONCLUSION

Collectively, these findings indicate that PhpA is a pivotal component of the RetS-GacS/GacA signaling network, highlighting its role in fine-tuning bacterial adaptation and biocontrol ability in P. bijieensis. © 2025 Society of Chemical Industry.