Oligogalacturonides in immunity and development

The recognition of endogenous molecules acting as “Damage-Associated Molecular Patterns” (DAMPs) is a key feature of the plant immunity. Oligogalacturonides (OGs), cell wall fragments derived from the degradation of the homogalacturonan, are a well-known class of DAMPs. The accumulation of OGs in vivo is favored by the interaction of microbial polygalacturonases (PGs) with plant PGinhibiting proteins (PGIPs). Transgenic Arabidopsis plants expressing an inducible PGIP-PG chimera, named "OG machine" (OGM), accumulate OGs on command in planta. If the release of OGs persists plant growth is inhibited and plants eventually die, reflecting the role of the OGs in the so-called growth-defense “trade-off”. A homeostatic control, which prevents deleterious effects of the over-accumulation of OGs, may rely on the oxidation of OGs, which impairs their signaling activity. Four OG oxidases, named OGOX1-4, that belong to the Berberine Bridge Enzyme-like (BBE-like) super-family have been identified in Arabidopsis. In this work the effects of the altered expression of OGOX1 on the defense responses induced by OGs and on the plant resistance to pathogens have been investigated by reverse genetics. The spatial features of OGOX1 expression during development and in response toelicitors and pathogens using promoter::reporter gene fusions is also described.