Arabidopsis Abscisic Acid Repressor 1 is a susceptibility hub that interacts with multiple <i>Pseudomonas syringae</i> effectors

Pathogens secrete effector proteins into host cells to suppress immunity and promote pathogen virulence, although many features at the molecular interface of host–pathogen interactions remain be characterized. In a yeast two-hybrid assay, we found that Pseudomonas syringae HopZ1a interacts with Arabidopsis transcriptional regulator Abscisic Acid Repressor 1 (ABR1). Further analysis revealed ABR1 multiple P. effectors, suggesting it may targeted as susceptibility hub. Indeed, loss-of-function abr1 mutants exhibit reduced number strains. The protein comprises conserved APETALA2 (AP2) domain flanked by long regions predicted structural disorder. We verified DNA-binding activity AP2 demonstrated disordered domains act redundantly enhance DNA binding facilitate activation ABR1. Finally, compared gene expression profiles from wild-type plants following inoculation syringae, which suggested is due loss virulence target rather than an enhanced immune response. These data highlight functionally important component interface.