Genomic and biological characterization of a new member of the genus Phikmvvirus infecting phytopathogenic Ralstonia bacteria

Abstract

Bacterial wilt caused by Ralstonia spp., soil-borne Gram-negative bacteria, is considered one of the most important plant diseases in tropical and subtropical regions of the world. A large number of bacteriophages capable of lysing or physiologically reprogramming cells of Ralstonia spp. have been reported in Asia. Despite the potential use of these organisms in the management of bacterial wilt, information on viruses that infect Ralstonia spp. is nonexistent in the Americas. We isolated a virus that infects Ralstonia spp. from a soil sample in the state of Minas Gerais, Brazil. Microscopy and genomic and phylogenetic analysis allowed us to classify the virus as a member of the family Podoviridae, genus Phikmvvirus. In spite of its relationship to Ralstonia virus RSB3, an Asian isolate, genomic and biological characteristics showed that the virus isolated in Brazil, tentatively named “Ralstonia virus phiAP1” (phiAP1), belongs to a new species. phiAP1 has EPS depolymerase activity and contains two putative virion-associated peptidoglycan hydrolases (VAPGHs), which reveals a robust mechanism of pathogenesis. Furthermore, phiAP1 specifically infects Ralstonia solanacearum, R. pseudosolanacearum and R. syzygii, causing cell lysis, but it was not able to infect thirteen other bacteria that were tested. Together, these characteristics highlight the biotechnological potential of this virus for the management of bacterial wilt.