Expression of the “OG-machine” in growth- and immune-defective Arabidopsis backgrounds identifies factors that uncouple growth inhibition from defence
Giulia De Lorenzo (Italy)1; Laura Guerrisi (Italy)1; Sara Di Renzo (Italy)1; Sarah Giulietti (Italy)1; Chiara Degli Esposti (Italy)1; Benedetta Mattei (Italy)2; Daniela Pontiggia (Italy)1;
1 - Sapienza, Università di Roma; 2 - Università dell'Aquila;
Keywords: Damage-Asspciated Molecular Patterns; Cell wall damage; Growth-defence trade-off;
Abstract Topics: Theme 9: Cell Wall Function and Signaling in plant adaptation to Biotic and Abiotic Stresses
Type of Presentation: Oral Communication

Abstract text: Oligogalacturonides (OGs) are prototypical cell wall DAMPs (damage-associated molecular patterns) that function as pleiotropic signals in both immunity and development. During fungal infection, immunoactive OGs are generated through controlled homogalacturonan hydrolysis by a dimeric enzyme formed by two interacting subunits from different organisms: a fungal polygalacturonase (PG) and a plant PG-inhibiting protein (PGIP). A chimeric gene encoding a fused PG–PGIP enzyme, termed the “OG-machine”, promotes OG production in planta and activates immune responses. However, elevated OG levels also inhibit plant growth, likely reflecting the natural trade-off between growth and defence. To identify key regulators at the intersection of these processes, we crossed multiple immune- and growth-defective Arabidopsis lines with OG-machine-expressing plants. Phenotypic characterization of the resulting lines identified RBOHD and EDS1 as critical contributors to OG-machine-induced growth reduction. Notably, resistance to Botrytis cinerea was retained in OG-machine-expressing lines in the rbohD and eds1 mutant backgrounds. Transcriptomic analyses further characterized the gene expression landscape associated with OGM-dependent resistance. These findings identify genetic components that may help uncouple defence activation from growth inhibition, addressing a major goal in plant biotechnology.