Phage Resistance in Synechococcus sp. WH8109
Phage resistance plays a central role in shaping cyanobacterial population dynamics and their interactions with viruses in the ocean. The coexistence of resistant and susceptible cells is likely one of the processes enabling hosts and phages to persist together. Yet the patterns and genetic basis of resistance are only partially resolved. Here, I examined genetically distinct populations of Synechococcus sp. WH8109 and found that resistance to the cyanophages Syn9 and S-TIP37 was consistently density-dependent across host populations. Whole genome sequencing of Syn9-resistant cyanobacteria revealed mutations in nine genes in the resistant strains. In a complementary approach, I investigated two porin-like genes previously implicated in resistance to phages S-TIP37 and Syn5. However, heterologous binding assays in E. coli did not conclusively establish their role in phage resistance. Together, these studies integrate ecological and genetic perspectives to advance understanding of the processes that govern host–phage coexistence in marine systems.
