The genetic and physiological basis ofArabidopsis thalianatolerance toPseudomonas viridiflava

Abstract

SUMMARYThe opportunistic pathogenPseudomonas viridiflavacolonizes more than fifty agricultural crop species and is the most commonPseudomonasin the phyllosphere of EuropeanArabidopsis thalianapopulations. Belonging to theP. syringaecomplex, it is genetically and phenotypically distinct from well-characterizedP. syringae sensu stricto. Despite its prevalence, we lack knowledge of howA. thalianaresponds to its native isolates at the molecular level. Here, we characterize the host response in anA. thaliana-P. viridiflavapathosystem.We measured host and pathogen growth in axenic infections, and used immune mutants, transcriptomics, and metabolomics to determine defense pathways influencing susceptibility toP. viridiflavainfection.Infection withP. viridiflavaincreased jasmonic acid (JA) levels and the expression of ethylene defense pathway marker genes. The immune response in a susceptible host accession was delayed compared to a tolerant one. Mechanical injury rescued susceptibility, consistent with an involvement of JA.The JA/ethylene pathway is important for suppression ofP. viridiflava, yet suppression capacity varies between accessions. Our results shed light on howA. thalianacan suppress the ever-presentP. viridiflava, but further studies are needed to understand howP. viridiflavaevades this suppression to spread broadly acrossA. thalianapopulations.