Functional analysis of the Pseudomonas syringae rulAB determinant in tolerance to ultraviolet B (290-320 nm) radiation and distribution of rulAB among P. syringae pathovars.
The effect of the plasmid-encoded rulAB (resistance to ultraviolet radiation) determinant on responses of Pseudomonas syringae to ultraviolet-B (UV-B) radiation and the distribution of rulAB among pathovars of P. syringae were determined. The cloned rulAB determinant and the native rulAB+ plasmid pPSR1 both conferred approximately a 10-fold increase in survival on P. syringae pv. syringae FF5 following increasing doses of UV-B radiation. rulAB+ P. syringae strains also maintained significantly larger epiphytic populations on leaf surfaces irradiated with UV-B. rulAB-insertional mutants, constructed in two native rulAB+ strains, were from 10- to 100-fold more sensitive to UV-B radiation. The UV tolerance phenotype and the rulAB genes were widely distributed among P. syringae pathovars isolated from varied plant hosts throughout the world and within a broad range of genotypic backgrounds of P. syringae pv. syringae. With one exception, the rulAB determinant was harboured on pPT23A-like plasmids; these replicons are indigenous residents of the species P. syringae and also tend to encode determinants of importance in host-pathogen interactions.
Sundin
G W
GW
Department of Plant Pathology and Microbiology, Texas A&M University, College Station 77843-2132, USA. gsundin@acs.tamu.edu
Murillo
J
J
D005798:Genes, Bacterial / Q000502:physiology*; D016254:Mutagenesis, Insertional; D010944:Plants / Q000382:microbiology*; D010957:Plasmids; D011549:Pseudomonas / Q000235:genetics / Q000528:radiation effects*; D011836:Radiation Tolerance / Q000235:genetics*; D014466:Ultraviolet Rays