Plant cell walls: source of carbohydrate-based signals in plant-pathogen interactions
Antonio Molina, Andrea Sánchez‐Vallet, Lucía Jordá, Cristian Carrasco‐López, José J. Rodríguez‐Herva, Emilia López‐Solanilla
Abstract
Plant cell walls are essential elements for disease resistance that pathogens need to overcome to colonise the host. Certain pathogens secrete a large battery of enzymes to hydrolyse plant cell wall polysaccharides, which leads to the release of carbohydrate-based molecules (glycans) that are perceived by plant pattern recognition receptors and activate pattern-triggered immunity and disease resistance. These released glycans are used by colonizing microorganisms as carbon source, chemoattractants to locate entry points at plant surface, and as signals triggering gene expression reprogramming. The release of wall glycans and their perception by plants and microorganisms determines plant-microbial interaction outcome. Here, we summarise and discuss the most recent advances in these less explored aspects of plant-microbe interaction. • Plant cell walls are dynamic defensive structures that pathogens must overcome to colonise plant tissues. • Plant cell walls are hydrolysed by cell wall degrading enzymes secreted by pathogens during infection. • Wall hydrolysis releases carbohydrate (glycans) that are perceived as alert signals by plant receptors triggering immunity. • Released glycans are used by microorganisms as chemoattractants and carbon source, improving plant colonisation. • Glycans at plant cell surface and apoplast might affect plant-microbial interaction outcome (resistance vs infection).