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

Abstract

Pathogens secrete effector proteins into host cells 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.

AtERF60,negatively regulatesABR1to modulate basal resistance response in Arabidopsis

“…Similar to our observation, induction of Arabidopsis ABR1 gene has been previously shown following infection with PstDC3000 (Schreiber et al, 2021). ABR1 contributes to plant immunity by interacting with Pseudomonas syringae effector molecule HopZ1a along with other different effectors (Schreiber et al, 2021).…”

“…is considered a functionally important molecule that interacts with different Pseudomonas syringae effectors (Schreiber et al, 2021). We sought to test our idea that AtERF60 regulates the central key component ABR1 and modulates plant response to biotic stress.…”

“…Later on, it was studied that ABR1 (group X of AP2/ERF) acts as a transcriptional activator and is involved in the wounding response (Baumler et al, 2019). ABR1 is an important molecule thought to play a functional role in the host-pathogen interface and acts as a susceptibility core that binds with different effector molecules of Pseudomonas syringae (Schreiber et al, 2021). Despite the importance of ABR1 involved in the regulation of both biotic and abiotic stress responses, its transcriptional regulator is not known.…”

The OsERF115/AP2EREBP110 Transcription Factor Is Involved in the Multiple Stress Tolerance to Heat and Drought in Rice Plants

“…While many AP2/ERFs are positively involved in the ABA signaling and ABA-mediated stress response, a few studies have reported AP2/ERFs function as a negative regulator of ABA response. The Arabidopsis group X ERF ABR1 (AtERF#111) has a dual function as a repressor of ABA response and activator of wounding or host-pathogen interaction [91][92][93]. The Arabidopsis ORA47 (AtERF18) specifically binds to a novel cis element O-box of ABI2 and inhibits ABA and JA signaling [94].…”

What the Wild Things Do: Mechanisms of Plant Host Manipulation by Bacterial Type III-Secreted Effector Proteins

“…Host defenses may also be enhanced by loss-of-function mutations in T3SE targets that negatively regulate immunity or that are activated by T3SEs to promote pathogen growth. These proteins are referred to as “susceptibility targets” and are of considerable interest as potential mediators of durable pathogen resistance, barring any detrimental effects on plant growth arising from the functional loss of such targets [ 377 , 378 , 379 , 380 , 381 ]. Overall, continued investigations of T3SE functions will address the need to “know thy enemy” and will help drive efforts to breed for durable resistance in agricultural crops.…”