DETECTION OF ERWINIA-CAROTOVORA SUBSP ATROSEPTICA AND ERWINIA-CHRYSANTHEMI IN POTATO-TUBERS USING POLYMERASE CHAIN-REACTION

Soft rot erwiniae are a group of notorious plant pathogens for which c urrently available detection methods are inadequate. Based on the poly merase chain reaction, specific and sensitive detection of Erwinia car otovora subsp. atroseptica and E. chrysanthemi in potato tubers has be en achieved. The composition of the PCR primers used in two specific d etection systems is based on identification of the consensus of sequen ces of metalloprotease-coding genes present in soft rot erwiniae. Bact erial DNA was extracted from the potato tuber matrix by differential c entrifugation in order to avoid interference of potato-derived compoun ds with the performance of the PCR assay. The PCR assay performed with the E. carotovora subsp. atroseptica specific primer set was found to be capable of distinguishing E. carotovora subsp. atroseptica from al l other Erwinia species and the closely related subspecies E. carotovo ra subsp. carotovora. With the E. chrysanthemi specific primer set, ag arose gel electrophoresis is required for unequivocal differentiation between E. chrysanthemi and other erwiniae. Combined with the efficien t extraction procedure, the assay allowed specific detection of less t han 10(3) culturable erwiniae per tuber. The specificity and sensitivi ty of the assay were not reduced in the presence of a 100-fold excess of DNA from both related and unrelated bacteria. This PCR-based method for detection of erwiniae in potato tubers provides a relatively fast and sensitive alternative to routinely applied serological methods.