Diverse mechanisms of resistance to Pseudomonas syringae in a thousand natural accessions of Arabidopsis thaliana

New Phytol. 2017 Jun;214(4):1673-1687. doi: 10.1111/nph.14517. Epub 2017 Mar 13.


Plants are continuously threatened by pathogen attack and, as such, they have evolved mechanisms to evade, escape and defend themselves against pathogens. However, it is not known what types of defense mechanisms a plant would already possess to defend against a potential pathogen that has not co-evolved with the plant. We addressed this important question in a comprehensive manner by studying the responses of 1041 accessions of Arabidopsis thaliana to the foliar pathogen Pseudomonas syringae pv. tomato (Pst) DC3000. We characterized the interaction using a variety of established methods, including different inoculation techniques, bacterial mutant strains, and assays for the hypersensitive response, salicylic acid (SA) accumulation and reactive oxygen species production . Fourteen accessions showed resistance to infection by Pst DC3000. Of these, two accessions had a surface-based mechanism of resistance, six showed a hypersensitive-like response while three had elevated SA levels. Interestingly, A. thaliana was discovered to have a recognition system for the effector AvrPto, and HopAM1 was found to modulate Pst DC3000 resistance in two accessions. Our comprehensive study has significant implications for the understanding of natural disease resistance mechanisms at the species level and for the ecology and evolution of plant-pathogen interactions.

Keywords: Arabidopsis thaliana; AvrPto; Pseudomonas syringae pv. tomato DC3000; effector-triggered immunity (ETI); plant immunity; plant pathogen; resistance mechanisms; salicylic acid (SA).

MeSH terms

  • Arabidopsis / microbiology*
  • Arabidopsis / physiology
  • Bacterial Proteins / metabolism
  • Cell Death
  • Disease Resistance / physiology*
  • Host-Pathogen Interactions / physiology
  • Mutation
  • Plant Diseases / microbiology*
  • Plant Leaves / microbiology
  • Pseudomonas syringae / genetics
  • Pseudomonas syringae / metabolism
  • Pseudomonas syringae / pathogenicity*
  • Reactive Oxygen Species / metabolism
  • Salicylic Acid / metabolism


  • Bacterial Proteins
  • Reactive Oxygen Species
  • avrPto protein, Pseudomonas syringae
  • Salicylic Acid