APS Homepage

Poster: Biology & Disease Mgmt: Virology


Isolation and characterization of ΦRs551, a bacteriophage associated with the phytobacterium Ralstonia solanacearum strain UW551
M. STULBERG (1), J. Mershon (2), A. Ahmad (3), D. Mollov (4), Q. Huang (2) (1) FNPRU, USDA/ARS & ORISE, U.S.A.; (2) FNPRU, USDA/ARS, U.S.A.; (3) FNPRU, USDA/ARS & Department of Plant Pathology, Faculty of Agriculture, Minia University, El-minia 61519, Egy

Ralstonia solanacearum species complex members are soil-borne, plant pathogenic bacteria that cause devastating diseases in a wide range of economically important crops around the world, with global losses in potato alone exceeding $950 million annually. The race 3 biovar 2 strains of R. solanacearum causing potato brown rot are listed as select agent pathogens due to their potential threat to U.S. agriculture. Genome analysis of the select agent strain UW551 revealed the presence of a putative intact prophage sequence with high homology to the family Inoviridae. Active virions of this phage, designated ΦRs551, were isolated from the supernatant of UW551 cells grown under normal culture conditions and were found to infect other R. solanacearum strains. Electron microscopy showed that ΦRs551 is a filamentous-type phage approximately 1200 nm long and 7 nm wide. ΦRs551 has a circular DNA genome that is 7929 nt in length, with 100% identity to the putative prophage sequence in the UW551 genome. It is most closely related to ΦRS603, another filamentous phage of Ralstonia isolated from soil. Our draft ΦRs551 genome contains open reading frames (ORFs) similar to those found in other Inoviridae members, but has a unique overall ORF makeup not found in any other phage relative.