Effects of Pseudomonas frederiksbergensis FC-17 on potato bacterial wilt and rhizosphere microbial community

Pseudomonas frederiksbergensis FC-17 shows prominent biological control for potato wilt disease caused by Ralstonia solanacearum . It remains unknown whether the biocontrol strain can effectively colonize rhizosphere soil and how it affects the bacterial community. Therefore, we used qPCR to track the abundance changes of FC-17 in the potato rhizosphere within 30 days after pathogen inoculation. The findings showed that applying bio-organic fertilizer, produced by secondary solid fermentation of organic fertilizer and FC-17, effectively improved disease control but did not enhance FC-17 colonization. 16S rRNA gene amplicon sequencing indicated that disease suppression was primarily attributed to the alterations in bacterial community composition, rather than the competitiveness of the inoculated FC-17 strain. Under pathogen pressure, bio-organic fertilizer treatment enriched specific bacterial genera, including Sphingomonas , Sphingobium , Lysobacter , and Isoptericola . Among these, Lysobacter and Sphingomonas were negatively correlated with the disease index, suggesting their potential role in suppressing potato bacterial wilt. This study elucidates a microbiome-mediated biocontrol mechanism, highlighting that optimizing the resident microbial community is a crucial strategy for sustainable disease management. Our results provide a theoretical foundation for combining P. frederiksbergensis with organic fertilizer to control potato bacterial wilt.