Experimental Coevolution Reveals That <i>Ralstonia pseudosolanacearum</i> <scp>PhcA</scp> Contributes to the Infection of Filamentous Phage <scp>RSCq</scp>

The interaction between bacteria and filamentous phages, particularly in the context of bacterial pathogenesis, remains poorly understood compared with the well-documented interactions involving lytic phages. Here, we investigated the coevolutionary dynamics between Ralstonia pseudosolanacearum, the causative agent of plant bacterial wilt disease, and filamentous phages. Experimental coevolution revealed the critical role of the global virulence regulator PhcA in filamentous phage infection, demonstrating that its requirement for successful filamentous phage infection is independent of the type IV pili receptor. Notably, while PhcA deficiency conferred phage resistance, it did not impair filamentous phage genome replication or egress. Moreover, trade-offs between filamentous phage resistance and bacterial virulence were observed, highlighting the potential implications of filamentous phage for biocontrol strategies against R. pseudosolanacearum. Overall, our findings shed light on the intricate interplay between Ralstonia pathogens and filamentous phages, providing insights into the development of novel approaches for disease management.