Quorum Sensing as a Target for Novel Biocontrol Strategies Directed at Pectobacterium

Members of the species Pectobacterium carotovorum and P. atrosepticum are pathogenic bacteria that are responsible for tissue maceration on various host plants. Pathogenicity essentially relies upon the production of plant cell wall degradation enzymes, the synthesis of which is regulated in a bacterial cell density dependent fashion, a process called quorum sensing (QS). This process involves key low molecular weight signal molecules belonging to the acyl homoserine lactone class. This paper reports on the various strategies that have been developed to prevent the expression of the pathogenicity determinants in Pectobacterium. These could target signal production, accumulation or sensing. Two approaches yield promising results in the Pectobacterium pathosystem: a biocontrol approach based on the isolation of strains able to degrade the QS signal, and a biostimulant approach based on amendment the plant environment with compounds favoring the growth of microbial consortia able to degrade the acyl homoserine lactones. The possibility to combine these two approaches is discussed.