The Arabidopsis thaliana gene AtERF019 negatively regulates plant resistance to Phytophthora parasiticaby suppressing PAMP-triggered immunity

Phytophthoraspecies are destructive plant pathogens that cause significant crop losses worldwide. To understand plant susceptibility to oomycete pathogens and to explore novel disease resistance strategies, we employed theArabidopsis thaliana-Phytophthora parasiticamodel pathosystem and screened forA. thalianaT-DNA insertion mutant lines resistant toP. parasitica. This led to the identification of the resistant mutant 267-31, which carries two T-DNA insertion sites in the promoter region of theethylene-responsive factor 19gene (ERF019). Quantitative reverse transcription PCR (RT-qPCR) assays showed that the expression ofERF019was induced duringP. parasiticainfection in the wild type, which was suppressed in the 267-31 mutant. Additionalerf019mutants were generated using CRISPR/Cas9 technology and were confirmed to have increased resistance toP. parasitica. In contrast,ERF019overexpression lines were more susceptible. Transient overexpression assays inNicotiana benthamianashowed that the nuclear localization ofERF019is crucial for its susceptible function. RT-qPCR analyses showed that the expression of marker genes for multiple defence pathways was significantly up-regulated in the mutant compared with the wild type during infection. Flg22-induced hydrogen peroxide accumulation and reactive oxygen species burst were impaired inERF019overexpression lines, and flg22-induced MAPK activation was enhanced inerf019mutants. Moreover, transient overexpression ofERF019strongly suppressed INF-triggered cell death inN. benthamiana. These results reveal the importance ofERF019in mediating plant susceptibility toP. parasiticathrough suppression of pathogen-associated molecular pattern-triggered immunity.