Cyclic-di-GMP Regulates the Quorum-Sensing System and Biocontrol Activity of Pseudomonas fluorescens 2P24 through the RsmA and RsmE Proteins

• Published in: Applied and environmental microbiology 2020-11, Vol.86 (24), p.1
• Main Authors: Liang, Fei, Zhang, Bo, Yang, Qingqing, Zhang, Yang, Zheng, Dehong, Zhang, Li-Qun, Yan, Qing, Wu, Xiaogang
• Format: Article
• Language: English
• Subjects: Antibiotics; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Biological control; Biological Control Agents - chemistry; Colonization; Cyclic GMP - analogs & derivatives; Cyclic GMP - metabolism; E coli; Genetics and Molecular Biology; Genomic analysis; Homoserine lactones; Lactones; Phosphodiesterase; Plant diseases; Proteins; Pseudomonas fluorescens; Pseudomonas fluorescens - genetics; Pseudomonas fluorescens - physiology; Quorum Sensing - genetics; Regulatory proteins; Rhizosphere; Soil-borne diseases
• ISSN: 0099-2240; 1098-5336; 1098-5336
• DOI: 10.1128/AEM.02016-20

2P24 is a rhizosphere bacterium that protects many crop plants against soilborne diseases caused by phytopathogens. The PcoI/PcoR quorum-sensing (QS) system and polyketide antibiotic 2,4-diacetylphloroglucinol (2,4-DAPG) are particularly relevant to the strain's biocontrol potential. In this study, we investigated the effects of c-di-GMP on the biocontrol activity of strain 2P24. The expression of the diguanylate cyclase (YedQ) and phosphodiesterase (YhjH) in 2P24 significantly increased and decreased the cellular concentration of c-di-GMP, respectively. The production of the QS signals -acyl homoserine lactones (AHLs) and 2,4-DAPG was negatively regulated by c-di-GMP in 2P24. The regulatory proteins RsmA and RsmE were positively regulated by c-di-GMP. Genomic analysis revealed that 2P24 has 23 predicted proteins that contain c-di-GMP-synthesizing or -degrading domains. Among these proteins, C0J56_12915, C0J56_13325, and C0J56_27925 contributed to the production of c-di-GMP and were also involved in the regulation of the QS signal and antibiotic 2,4-DAPG production in Overexpression of C0J56_12915, C0J56_13325, and C0J56_27925 in 2P24 impaired its root colonization and biocontrol activities. Taken together, these results demonstrated that c-di-GMP played an important role in fine-tuning the biocontrol traits of In various bacteria, the bacterial second messenger c-di-GMP influences a wide range of cellular processes. However, the function of c-di-GMP on biocontrol traits in the plant-beneficial rhizobacteria remains largely unclear. The present work shows that the QS system and polyketide antibiotic 2,4-DAPG production are regulated by c-di-GMP through RsmA and RsmE proteins in 2P24. The diguanylate cyclases (DGCs) C0J56_12915, C0J56_13325, and C0J56_27925 are especially involved in regulating the biocontrol traits of 2P24. Our work also demonstrated a connection between the Gac/Rsm cascade and the c-di-GMP signaling pathway in .