Pectic Enzymes Produced In vitro and In vivo by Erwinia spp. Isolated from Carrot and Pepper in Egypt

Thirty soft-rot Erwinia strains were isolated from diseased carrot (Daucus carrota) roots and pepper (Capsicum annuum) fruits. Pathogenicity tests showed that these strains are able to induce soft-rot disease symptoms in different vegetable species indicating a wide host range. Although pectin methyl esterase and polygalacturonase activities were not detected in culture supernatants, they were found in extracts of carrot roots and pepper fruits infected with three strains representingthree soft-rot Erwinias. On the other hand, culture supernatants and extracts of infected plant tissues contained pectic lyase activity. The enzyme from either sodium polypectate or pectin medium degraded the former more actively than the latter indicatingpe ctate rather than pectin lyase activity. In contrast, the enzyme produced in infected tissue showed higher activity on pectin than sodium polypectate. Moreover, the enzyme activity on pectin was not reduced in the absence of Ca2+, which might suggest that, in addition to pectate lyases, pectin lyases could be produced in plant tissues by Erwinia species