title: A large, mobile pathogenicity island confers plant pathogenicity on Streptomyces species.
abstract: Potato scab is a globally important disease caused by polyphyletic plant pathogenic Streptomyces species. Streptomyces acidiscabies, Streptomyces scabies and Streptomyces turgidiscabies possess a conserved biosynthetic pathway for the nitrated dipeptide phytotoxin thaxtomin. These pathogens also possess the nec1 gene which encodes a necrogenic protein that is an independent virulence factor. In this article we describe a large (325-660 kb) pathogenicity island (PAI) conserved among these three plant pathogenic Streptomyces species. A partial DNA sequence of this PAI revealed the thaxtomin biosynthetic pathway, nec1, a putative tomatinase gene, and many mobile genetic elements. In addition, the PAI from S. turgidiscabies contains a plant fasciation (fas) operon homologous to and colinear with the fas operon in the plant pathogen Rhodococcus fascians. The PAI was mobilized during mating from S. turgidiscabies to the non-pathogens Streptomyces coelicolor and Streptomyces diastatochromogenes on a 660 kb DNA element and integrated site-specifically into a putative integral membrane lipid kinase. Acquisition of the PAI conferred a pathogenic phenotype on S. diastatochromogenes but not on S. coelicolor. This PAI is the first to be described in a Gram-positive plant pathogenic bacterium and is responsible for the emergence of new plant pathogenic Streptomyces species in agricultural systems.
authors.affiliation: Department of Plant Pathology, Cornell University, Ithaca, NY, USA.
authors.forename: Johan A
authors.initials: JA
authors.lastname: Kers
authors.forename: Kimberly D
authors.initials: KD
authors.lastname: Cameron
authors.forename: Madhumita V
authors.initials: MV
authors.lastname: Joshi
authors.forename: Raghida A
authors.initials: RA
authors.lastname: Bukhalid
authors.forename: Joanne E
authors.initials: JE
authors.lastname: Morello
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Wach
authors.forename: Donna M
authors.initials: DM
authors.lastname: Gibson
authors.forename: Rosemary
authors.initials: R
authors.lastname: Loria
mesh_terms: D001483:Base Sequence; D004269:DNA, Bacterial / Q000235:genetics; D004798:Enzymes / Q000235:genetics; D010935:Plant Diseases / Q000382:microbiology*; D010940:Plant Proteins / Q000235:genetics; D010944:Plants / Q000382:microbiology*; D011198:Solanum tuberosum / Q000382:microbiology; D013302:Streptomyces / Q000145:classification / Q000235:genetics / Q000472:pathogenicity*; D014774:Virulence
chemical_list: D004269:DNA, Bacterial; D004798:Enzymes; D010940:Plant Proteins