[Contribution of cell and molecular biology and genetics to plant protection]

Plants resist to the majority of their potential aggressors by opposing physical and chemical barriers: cell walls, secondary metabolites.... Phenomena of specific recognition between a plant variety and a pathovar induce on the one hand, a local (hypersensitive) reaction that tends to limit pathogen growth and, on the other hand, a cascade of signals that allows the activation of a non-specific general (systemic) resistance. The contribution of genetics to the fight against pathogens depends on the natural variability that comes from the co-evolution between plants and their aggressors. Many plant varieties resistant to one or several pathogens have been obtained and are cultivated. The use of biotechnology will facilitate the rapid generation of new, resistant cultivars and cultivars with multiple resistances. New methods in order to increase the efficiency and the durability of resistance are envisaged.