EN
The enterobacterium Erwinia causes soft rot disease in various plants. Erwinia pathogenicity results from the secretion of pectinolytic and cellulolytic enzymes responsible for the deterioration of the plant cell wall. It produces pectin methylesterases, several pectate lyases, polygalacturonase, pectin lyase, cellulases and hemicellulase. Regulation of pectinases genes requires several regulatory systems. Deletion of the major pectate lyase genes from Erwinia genome failed to totally eliminate tissue maceration. Structural genes for secondary pectate lyase were cloned and sequenced. The important role of the secondary pelL gene in the development of infection was demonstrated.