Ricerc@Sapienza

Pectin is synthesized in a highly methylesterified form in the Golgi cisternae and partially de-methylesterified in muro by pectin methylesterases (PMEs). Arabidopsis thaliana produces a local and strong induction of PME activity during the infection of the necrotrophic fungus Botrytis cinerea. AtPME17 is a putative A. thaliana PME highly induced in response to B. cinerea. Here, a fine tuning of AtPME17 expression by different defence hormones was identified.

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.

Oligogalacturonides (OGs) are pectic fragments derived from the partial degradation of homogalacturonan in the plant cell wall and able to elicit plant defence responses. Recent methodological advances in the isolation of OGs from plant tissues and their characterization have confirmed their role as bona fide plant Damage-Associated Molecular Patterns. Here, we describe the methods for the isolation of OGs from Arabidopsis leaf tissues and for the characterization of OG structure and biological activity.