CHARACTERIZATION OF ERWINIA-CHRYSANTHEMI BY PECTINOLYTIC ISOZYME POLYMORPHISM AND RESTRICTION-FRAGMENT-LENGTH-POLYMORPHISM ANALYSIS OF PCR-AMPLIFIED FRAGMENTS OF PEL GENES

Conserved regions about 420 bp long of the pelADE cluster specific to Erwinia chrysanthemi were amplified by PCR and used to differentiate 7 8 strains of E, chrysanthemi that were obtained from different hosts a nd geographical areas, No PCR products were obtained from DNA samples extracted from other pectinolytic and nonpectinolytic species and gene ra, The pel fragments amplified from the E, chrysanthemi strains studi ed were compared by performing a restriction fragment length polymorph ism (RFLP) analysis. On the basis of similarity coefficients derived f rom the RFLP analysis, the strains were separated into 16 PCR RFLP pat terns grouped in six clusters, These clusters appeared to be correlate d with other infraspecific levels off. chrysanthemi classification, su ch as pathovar and biovar, and occasionally with geographical origin, Moreover, the clusters correlated well with the polymorphism of pectat e lyase and pectin methylesterase isoenzymes. While the pectin methyle sterase profiles correlated with host monocot-dicot classification, th e pectate lyase polymorphism might reflect the cell wall microdomains of the plants belonging to these classes.