Phage WO Diversity and Evolutionary Dynamics Associated With Wolbachia-infected Crickets

Wolbachia is a maternally inherited endosymbiont in the phylum Proteobacteria and it is found widely in arthropods and nematodes. These bacteria can manipulate reproduction of their hosts. Phage WO is the only bacteriophage known to infect Wolbachia, and it could provide benefits to its host or arthropods. In order to investigate the diversity and evolutionary dynamics of phage WO, we screened for the presence of phage WO in Wolbachia-infected cricket species from China for the first time. Among 21 cricket species infected with Wolbachia, 20 species harbored phage WO. Interestingly, 12 of 20 cricket species harbored multiple phage types (ranging from two to 10 types), and another eight species harbored one phage type. In total, 12 phage WO horizontal transmission events were detected, where common phage WO types were shared among different Wolbachia strains associated with crickets. These results suggest that the horizontal acquisition of phage WO might also occur between eukaryotes without Wolbachia transfer. Furthermore, nine putative recombination events were identified in seven cricket species that harbored multiple phage types. These results indicate that the horizontal transmission of phage WO and intragenic recombination were important for the evolution of the phage WO genome by effectively increasing the phage WO diversity associated with crickets.arthropods and nematodes. The bacteria could manipulate the reproduction of its hosts. Phage WO is the only bacteriophage known to infect Wolbachia, and could provide benefit to its host or arthropods. In order to investigate their diversity and evolutionary dynamics, we screened for the presence of phage WO in Wolbachia-infected cricket species from China for the first time. Of the 21 cricket species infected with Wolbachia, 20 species harbored phage WO. Interestingly, 12 of 20 cricket species harbored multiple phage types (ranging from 2 to 10 types), and another eight species harbored one phage types. A total of 12 horizontal transmission events of phage WO were found, which shared common phage WO types among different Wolbachia strains associated with crickets. It is suggested that horizontal acquisition of phage WO might also occur between eukaryotes without Wolbachia transfer. Furthermore, nine putative recombination events were identified in seven cricket species which harbored multiple phage types. These results showed that horizontal transmission of phage WO, as well as intragenic recombination were important dynamics for phage WO genome evolution, which effectively promoted the phage WO diversity associated with crickets.