Ricerc@Sapienza

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

The architecture of the plant cell wall is highly dynamic, being substantially re-modeled during growth and development. Cell walls determine the size and shape of cells and contribute to the functional specialization of tissues and organs. Beyond the physiological dynamics, the wall structure undergoes changes upon biotic or abiotic stresses. In this review several cell wall traits, mainly related to pectin, one of the major matrix components, will be discussed in relation to plant development, immunity and industrial bioconversion of biomass, especially for energy production.

Infection by necrotrophic fungi is a complex process that starts with the breakdown of the cell wall (CW) matrix initiated by CW degrading enzymes and results in extensive tissue maceration. Plant can exploit induced defense mechanisms based on biochemical modification of the CW components to protect themselves from the pathogen. We found that plants activate CW remodeling mechanisms based on matrix strengthening, callose deposition and synthesis of structural defense proteins to resist to CW degradation upon necrotroph infection.

Pectic homogalacturonan (HG) is one of the main constituents of plant cell walls. When processed to low degrees of esterification, HG can form complexes with divalent calcium ions. These macromolecular structures (also called egg boxes) play an important role in determining cell wall biomechanics and in mediating cell-to-cell adhesion. Current immunological methods enable only steady-state detection of egg box formation in situ. Here we present a tool for efficient real-time visualisation of available sites for HG crosslinking within cell wall microdomains.