Two asian jumbo phages, φRSL2 and φRSF1, infect Ralstonia solanacearum and show common features of φKZ-related phages

Jumbo phages infecting Ralstonia solanacearum were isolated in Thailand (phi RSL2) and Japan (phi RSF1). They were similar regarding virion morphology, genomic arrangement, and host range. Phylogenetic and proteomic tree analyses demonstrate that the phi RSL2 and phi RSF1 belong to a group of evolutionary related phages, including Pseudomonas phages phi KZ, 201 phi 2-1 and all previously described phi KZ-related phages. Despite conserved genomic co-linearity between the phi RSL2 and phi RSF1, they differ in protein separation patterns. A major difference was seen in the detection of virion-associated-RNA polymerase subunits. All beta- and beta'-subunits were detected in phi RSF1, but one beta'-subunit was undetected in phi RSL2. Furthermore, phi RSF1 infected host cells faster (latent period: 60 and 150 min for phi RSF1 and phi RSL2, respectively) and more efficiently than phi RSL2. Therefore, the difference in virion-associated-RNA polymerase may affect infection efficiency. Finally, we show that phi RSF1 is able to inhibit bacterial wilt progression in tomato plants. (C) 2016 Elsevier Inc. All rights reserved.