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ARS Home » Pacific West Area » Albany, California » Plant Gene Expression Center » Research » Publications at this Location » Publication #378889

Research Project: Mining Collections of Wild Germplasm and Novel Defense Regulators for Enhanced Plant Defenses

Location: Plant Gene Expression Center

Title: Arabidopsis Abscisic Acid Repressor 1 (ABR1) is a susceptibility hub that interacts with multiple Pseudomonas syringae effectors

item SCHREIBER, KARL - University Of California
item HASSAN, JANA - University Of California
item Lewis, Jennifer

Submitted to: Plant Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/23/2020
Publication Date: 12/2/2020
Citation: Schreiber, K.J., Hassan, J.A., Lewis, J.D. 2020. Arabidopsis Abscisic Acid Repressor 1 (ABR1) is a susceptibility hub that interacts with multiple Pseudomonas syringae effectors. Plant Journal. 105(5):1274-1292.

Interpretive Summary: Plant pathogenic bacteria cause substantial yield losses in crop plants. Bacteria carry effector proteins which primarily promote virulence of the bacteria. One way that disease resistance can be enhanced in plants involves disrupting mechanisms commonly used by pathogens to promote their virulence. We demonstrate that a transcriptional regulator, Abscisic Acid Regulator 1, interacts with multiple effector proteins from the plant pathogenic bacterium Pseudomonas syringae. Loss of ABR1 resulted in less susceptibility to P. syringae infection without negatively impacting plant growth. This work suggests that ABR1 is a worthwhile target for engineering improved disease resistance in crop plants.

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