Host Cell Wall Damage during Pathogen Infection: Mechanisms of Perception and Role in Plant-Pathogen Interactions.
The plant cell wall (CW) is a complex structure that acts as a mechanical barrier, restricting
the access to most microbes. Phytopathogenic microorganisms can deploy an arsenal of CWdegrading
enzymes (CWDEs) that are required for virulence. In turn, plants have evolved proteins
able to inhibit the activity of specific microbial CWDEs, reducing CW damage and favoring the
accumulation of CW-derived fragments that act as damage-associated molecular patterns (DAMPs)
and trigger an immune response in the host. CW-derived DAMPs might be a component of the
complex system of surveillance of CW integrity (CWI), that plants have evolved to detect changes
in CW properties. Microbial CWDEs can activate the plant CWI maintenance system and induce
compensatory responses to reinforce CWs during infection. Recent evidence indicates that the CWI
surveillance system interacts in a complex way with the innate immune system to fine-tune
downstream responses and strike a balance between defense and growth.