AefR, a TetR Family Transcriptional Repressor, Regulates Several Auxin Responses in Strain DC3000.

The plant hormone indole-3-acetic acid (IAA), also known as auxin, plays important roles in plant growth and development, as well as in several plant-microbe interactions. IAA also acts as a microbial signal and in many bacteria regulates metabolism, stress responses, and virulence. In the bacterial plant pathogen pv. strain DC3000 (DC3000), exposure to IAA results in large-scale transcriptional reprogramming, including the differential expression of several known virulence genes. However, how DC3000 senses and responds to IAA and what aspects of its biology are regulated by IAA is not understood. To investigate the mechanisms involved in perceiving and responding to IAA, we carried out a genetic screen for mutants with altered responses to IAA. One group of mutants of particular interest carried disruptions in the gene encoding a TetR family transcriptional regulator. Gene expression analysis confirmed that the mutants have altered responses to IAA. Thus, AefR is the first demonstrated auxin response regulator in DC3000. We also investigated several aspects of DC3000 biology that are regulated by both AefR and IAA, including antibiotic resistance, motility, and virulence. The observation that the mutant has altered virulence on , suggests that the sector of the IAA response regulated by is important during pathogenesis. Our findings also provide evidence that AefR plays a role in coordinating changes in gene expression during the transition from early to late stages of infection. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.