Dampening a DAMP: a specific oxidase regulates homeostasis of oligogalacturonides and growth in Arabidopsis
G. DE LORENZO (1), M. Benedetti (1), I. Verrascina (2), D. Pontiggia (1), D. Savatin (1), B. Mattei (1), F. Cervone (1) (1) Università di Roma Sapienza, Italy; (2) Università di Roma Sapienza, Italy

Recognition of endogenous molecules released during the infection process and acting as “damage-associated molecular patterns” (DAMPs) is a key feature of immunity in both animals and plants. In Arabidopsis, a tailored release of oligogalacturonides (OGs), i.e. DAMPs derived from the rupture of the cell wall pectin, enhances immunity and confers resistance against several microbial pathogens. Besides inducing immunity, OGs negatively affect plant growth and developmental responses. Because the recognition of DAMPs poses the intrinsic risk of activating an exaggerated response that reduces or completely arrests plant growth, homeostatic mechanisms must exist that prevent DAMP hyper-accumulation. We looked for such a regulatory mechanism by searching for modified elicitor-inactive OGs in Arabidopsis transgenic plants that express, in a β-estradiol-inducible manner, an “OG machine” formed by the fusion of a fungal polygalacturonase and a plant-derived polygalacturonase inhibitor. In the presence of β-estradiol, these plants contain increased levels of elicitor-active OGs. Modified OGs were extracted from these plants that derived from the oxidation of the reducing ends. Oxidized OGs were unable to activate immune responses. We show that plants are endowed with an enzymatic system for the specific oxidation of OGs and the inactivation of their capability of acting as elicitors. This mechanism emerges as a key element for controlling homeostasis of this class of DAMPs.

Abstract Number: C18-1
Session Type: Concurrent