Figure 4.

Selected adaptive mechanisms used by animal and plant pathogens as well as plant-associated bacteria to survive within their hosts. These mechanisms include secretion and delivery of effectors which interfere with host immune signaling. Bacterial sensors can be activated in response to different environmental cues such as pH or nutrients, to modulate expression of their regulons, leading to gene expression reprogramming and favoring bacterial adaptation. Dedicated bacterial enzymes can be used (i) to metabolize nutrients and (ii) to modify the host microenvironment, both reactions conferring to the pathogen an advantage over the competing microbiota. Biofilm formation and cell aggregation may also play a role in the adaptation to the plant environment and allow an increased protection against stresses. Bacterial competition involves the release of antagonistic molecules, peptides and proteins or the direct delivery of toxins.