title: Comparative large-scale analysis of interactions between several crop species and the effector repertoires from multiple pathovars of Pseudomonas and Ralstonia.
abstract: Bacterial plant pathogens manipulate their hosts by injection of numerous effector proteins into host cells via type III secretion systems. Recognition of these effectors by the host plant leads to the induction of a defense reaction that often culminates in a hypersensitive response manifested as cell death. Genes encoding effector proteins can be exchanged between different strains of bacteria via horizontal transfer, and often individual strains are capable of infecting multiple hosts. Host plant species express diverse repertoires of resistance proteins that mediate direct or indirect recognition of bacterial effectors. As a result, plants and their bacterial pathogens should be considered as two extensive coevolving groups rather than as individual host species coevolving with single pathovars. To dissect the complexity of this coevolution, we cloned 171 effector-encoding genes from several pathovars of Pseudomonas and Ralstonia. We used Agrobacterium tumefaciens-mediated transient assays to test the ability of each effector to induce a necrotic phenotype on 59 plant genotypes belonging to four plant families, including numerous diverse accessions of lettuce (Lactuca sativa) and tomato (Solanum lycopersicum). Known defense-inducing effectors (avirulence factors) and their homologs commonly induced extensive necrosis in many different plant species. Nonhost species reacted to multiple effector proteins from an individual pathovar more frequently and more intensely than host species. Both homologous and sequence-unrelated effectors could elicit necrosis in a similar spectrum of plants, suggesting common effector targets or targeting of the same pathways in the plant cell.
authors: Genome Center and Department of Plant Sciences, University of California, Davis, California 95616, USA.
authors: Tadeusz
authors: T
authors: Wroblewski
authors: Katherine S
authors: KS
authors: Caldwell
authors: Urszula
authors: U
authors: Piskurewicz
authors: Keri A
authors: KA
authors: Cavanaugh
authors: Huaqin
authors: H
authors: Xu
authors: Alexander
authors: A
authors: Kozik
authors: Oswaldo
authors: O
authors: Ochoa
authors: Leah K
authors: LK
authors: McHale
authors: Kirsten
authors: K
authors: Lahre
authors: Joanna
authors: J
authors: Jelenska
authors: Jose A
authors: JA
authors: Castillo
authors: Daniel
authors: D
authors: Blumenthal
authors: Boris A
authors: BA
authors: Vinatzer
authors: Jean T
authors: JT
authors: Greenberg
authors: Richard W
authors: RW
authors: Michelmore
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D018556:Crops, Agricultural / Q000145:classification / Q000235:genetics / Q000382:microbiology*; D017343:Genes, Plant; D054884:Host-Pathogen Interactions; D018545:Lactuca / Q000235:genetics / Q000382:microbiology; D018551:Solanum lycopersicum / Q000235:genetics / Q000382:microbiology; D009336:Necrosis; D010641:Phenotype; D011110:Polymorphism, Genetic; D011549:Pseudomonas / Q000472:pathogenicity / Q000502:physiology*; D043367:Ralstonia / Q000472:pathogenicity / Q000502:physiology*; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D014774:Virulence
chemical_list: D001426:Bacterial Proteins