Phytopathogenic bacteria perceive plant-derived compounds to ensure plant entry and the onset of the infection

Foliar bacterial pathogens have to penetrate the plant tissue and access the interior of the apoplast in order to initiate the pathogenic phase. The entry process is driven by chemotaxis towards plant-derived compounds in order to locate plant openings. However, information on plant signals recognized by bacterial chemoreceptors is scarce. In this work, it is shown that the perception of g-aminobutyric acid (GABA) and L-Pro, two abundant components of the tomato apoplast, through the Pseudomonas syringae pv. tomato (PsPto) PscC chemoreceptor drives the entry of this bacterium into the plant. The recognition of these compounds by PsPto-PscC causes chemoattraction to both amino acids, participating in the regulation of GABA metabolism. Inactivation of the PsPto-PscC chemoreceptor decreases the chemotactic response towards the compounds, impairing bacterial entry into leaves, and reducing its virulence in tomato plants. Interestingly, GABA and L-Pro levels significantly increase in tomato plants upon pathogen infection and are involved in the regulation of the plant defence response. This is a clear example illustrating how bacteria respond to plant signals produced during the interaction as cues to access the plant apoplast and to ensure efficient infection.


Original Paper:

Santamaría-Hernando, S., López-Maroto, Á., Galvez-Roldán, C., Munar-Palmer, M., Monteagudo-Cascales, E., Rodríguez-Herva, J.-J., Krell, T., López-Solanilla, E. n.d. Pseudomonas syringae pv. tomato infection of tomato plants is mediated by GABA and l-Pro chemoperception. Molecular Plant Pathology n/a. DOI: 10.1111/mpp.13238