Volatile Organic Compounds from Pseudomonas koreensis KF32 and P. fitomaticsae KF45 Suppress Ralstonia pseudosolanacearum and Reduce Bacterial Wilt in Tomato.

Bacterial wilt caused by Ralstonia pseudosolanacearum is a destructive disease with a broad host range and global impact. To explore eco-friendly biocontrol strategies for bacterial wilt, we screened Pseudomonas strains that produce volatile organic compounds (VOCs) with antibacterial activity against R. pseudosolanacearum and potential biocontrol effects on tomato bacterial wilt. We evaluated antibacterial activity of VOCs produced by bacterial strains using on I-plate, and conducted plant assays against of bacterial wilt tomato plant. Two strains, KF32 and KF45, were identified as Pseudomonas koreensis, and P. fitomaticsae, respectively. Their VOCs significantly inhibited R. pseudosolanacearum growth in vitro and reduced disease incidence in tomato plants. Transcriptomic analysis was performed on R. pseudosolanacearum exposed to VOCs from strains KF32 and KF45. RNA sequencing revealed that VOCs from KF32 and KF45 downregulated genes related to cell motility and xenobiotic degradation of the pathogen. We analyzed VOCs produced by strains KF32 and KF45 using gas chromatography-mass spectrometry. Among the identified VOCs, 2-decanone which was produced by strain KF32 significantly inhibited the growth of R. pseudosolanacearum and reduced tomato bacterial wilt symptoms. This study highlights the potential of VOC-producing Pseudomonas strains KF32 and KF45 as biocontrol agents and contributing to the development of long-term strategies for managing bacterial wilt in tomato. Furthermore, understanding VOC-mediated interactions provides valuable insights for developing improved strategies to manage plant pathogenic bacteria.