Acetylcholine signaling regulates osmotic stress adaptation in the phytopathogen Dickeya solani

The adaptation of plant-associated bacteria to their hosts relies on an extensive repertoire of signal transduction systems that sense plant-derived molecules and dynamically adjust bacterial physiology and metabolism within the holobiont. These signals include key plant signaling compounds that regulate processes essential for plant–microbe interactions.

Among them, acetylcholine is emerging as an important signaling molecule in both plants and bacteria. Here, we demonstrate that acetylcholine regulates the expression of the osmotic stress response betIBA gene cluster in the phytopathogen Dickeya solani, where it plays an important role in osmoprotection. We show that the TetR-family transcriptional regulator associated with this pathway, BetIDs, recognizes acetylcholine as well as choline and trimethylamine.