Determination of enzymatic activities implicated in the virulence of Pectobacterium carotovorum subsp. carotovorum and Dickeya chrysanthemi isolated from potato

Abstract

The plant pathogenic bacteria Pectobacterium carotovorum subsp. carotovorum and Dickeya chrysanthemi can cause severe economic damage to potato and other plant crops. Progression of the disease requires the action of extracellular enzymes produced by these bacteria that degrade the cell walls of host plants. The activities of pectate lyase, polygalacturonase, cellulase and protease from four strains of P. carotovorum subsp. carotovorum and four strains of D. chrysanthemi were determined in vitro. The highest maceration ability on potato tubers of Spunta cultivar were found for Q35, Ms11, B13 of the latter species, E505, E1003 and Alq41 of carotovorum while E1105 and Art41 belonging to£the frst and the second species respectively were less virulent. For D. chrysanthemi the elevated virulence was related with a high pectate lyase and cellulase activities ranging from 2.4 to 4.6 U and 0.24 to 0.3 U, respectively. In the case of subspecies carotovorum the high level of virulence was associated with a high polygalacturonase activity between 1.1 and 1.7 U. The highest protease activity with gelatine hydrolysis halos above 18 mm, corresponded to Ms11 and Q35. For the rest of the strains, the values were similar, except for E1105 where this enzymatic activity was not detected.