2025-09-09 ワシントン大学セントルイス校
Spots on a tomato indicate bacteria infestation. WashU researchers have identified the protein involved in these costly plant infestations. (Photo: Shutterstock)
＜関連情報＞
- https://source.washu.edu/2025/09/how-harmful-bacteria-hijack-crops/
- https://artsci.washu.edu/ampersand/how-harmful-bacteria-hijack-our-crops
- https://journals.asm.org/doi/10.1128/mbio.01152-25
PmeR, a TetR-like transcriptional regulator, is involved in both auxin signaling and virulence in the plant pathogen Pseudomonas syringae strain PtoDC3000
Chia-Yun Lee, Maya Irvine, Barbara Kunkel
mBio Published:20 August 2025
DOI:https://doi.org/10.1128/mbio.01152-25
ABSTRACT
Plant pathogenic bacteria, such as Pseudomonas syringae strain PtoDC3000, respond to host signals through complex signaling networks that regulate bacterial growth and virulence. The plant hormone indole-3-acetic acid (IAA), also known as auxin, promotes bacterial pathogenesis via multiple mechanisms, including through reprogramming of bacterial transcription. However, the mechanisms that PtoDC3000 uses to sense and respond to auxin are not well understood. Here, we identify a novel bacterial auxin-signaling mechanism mediated by pmeR, which encodes a TetR-like family transcriptional repressor that acts as an important regulator of IAA-responsive gene expression in PtoDC3000. Using qRT-PCR and transcriptional reporter assays, we show that pmeR is induced by IAA and regulates several auxin-responsive genes. pmeR plays two different roles in the regulation of auxin-responsive genes: as a repressor of its own expression and as an activator of other genes. Plant infection assays further show that the disruption of pmeR results in reduced bacterial growth in Arabidopsis thaliana. Notably, although PmeR de-represses the transcription of pmeR upon IAA treatment, it does not appear to directly bind IAA. Rather, our biochemical results indicate that the auxin conjugate IAA-lysine may serve as a ligand for PmeR. Our findings reveal a complex signaling network through which IAA modulates bacterial gene expression and emphasize the role of PmeR in acclimating PtoDC3000 for growth in plant tissue.
