title: Rice-Infecting Pseudomonas Genomes Are Highly Accessorized and Harbor Multiple Putative Virulence Mechanisms to Cause Sheath Brown Rot.
abstract: Sheath rot complex and seed discoloration in rice involve a number of pathogenic bacteria that cannot be associated with distinctive symptoms. These pathogens can easily travel on asymptomatic seeds and therefore represent a threat to rice cropping systems. Among the rice-infecting Pseudomonas, P. fuscovaginae has been associated with sheath brown rot disease in several rice growing areas around the world. The appearance of a similar Pseudomonas population, which here we named P. fuscovaginae-like, represents a perfect opportunity to understand common genomic features that can explain the infection mechanism in rice. We showed that the novel population is indeed closely related to P. fuscovaginae. A comparative genomics approach on eight rice-infecting Pseudomonas revealed heterogeneous genomes and a high number of strain-specific genes. The genomes of P. fuscovaginae-like harbor four secretion systems (Type I, II, III, and VI) and other important pathogenicity machinery that could probably facilitate rice colonization. We identified 123 core secreted proteins, most of which have strong signatures of positive selection suggesting functional adaptation. Transcript accumulation of putative pathogenicity-related genes during rice colonization revealed a concerted virulence mechanism. The study suggests that rice-infecting Pseudomonas causing sheath brown rot are intrinsically diverse and maintain a variable set of metabolic capabilities as a potential strategy to occupy a range of environments.
authors.affiliation: Plant Breeding, Genetics, and Biotechnology Division, International Rice Research Institute, Los Baños, Philippines.
authors.forename: Ian Lorenzo
authors.initials: IL
authors.lastname: Quibod
authors.affiliation: Plant Breeding, Genetics, and Biotechnology Division, International Rice Research Institute, Los Baños, Philippines.
authors.forename: Genelou
authors.initials: G
authors.lastname: Grande
authors.affiliation: Plant Breeding, Genetics, and Biotechnology Division, International Rice Research Institute, Los Baños, Philippines.
authors.forename: Eula Gems
authors.initials: EG
authors.lastname: Oreiro
authors.affiliation: T.T. Chang- Genetic Resources Center, International Rice Research Institute, Los Baños, Philippines.
authors.forename: Frances Nikki
authors.initials: FN
authors.lastname: Borja
authors.affiliation: Plant Breeding, Genetics, and Biotechnology Division, International Rice Research Institute, Los Baños, Philippines; Department of Phytomedicine, Leibniz Universität Hannover, Hannover, Germany.
authors.forename: Gerbert Sylvestre
authors.initials: GS
authors.lastname: Dossa
authors.affiliation: T.T. Chang- Genetic Resources Center, International Rice Research Institute, Los Baños, Philippines.
authors.forename: Ramil
authors.initials: R
authors.lastname: Mauleon
authors.affiliation: Plant Breeding, Genetics, and Biotechnology Division, International Rice Research Institute, Los Baños, Philippines.
authors.forename: Casiana Vera
authors.initials: CV
authors.lastname: Cruz
authors.affiliation: Plant Breeding, Genetics, and Biotechnology Division, International Rice Research Institute, Los Baños, Philippines.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Oliva
mesh_terms: D019143:Evolution, Molecular; D016680:Genome, Bacterial / Q000235:genetics*; D054884:Host-Pathogen Interactions; D012275:Oryza / Q000378:metabolism / Q000382:microbiology*; D010802:Phylogeny; D010858:Pigmentation; D010935:Plant Diseases / Q000382:microbiology*; D011549:Pseudomonas / Q000235:genetics* / Q000472:pathogenicity* / Q000502:physiology; D012639:Seeds / Q000378:metabolism / Q000382:microbiology; D012641:Selection, Genetic; D014774:Virulence