STUDIES ON PECTOLYTIC ERWINIA SPP IN PORTUGAL REVEAL UNUSUAL STRAINS OF E CAROTOVORA SUBSP ATROSEPTICA
A.B. Costa, M. Eloy, L. Cruz, J.D. Janse, H. Oliveira
The bacterial pathogens Erwinia carotovora subsp. atroseptica, E. carotovora subsp. carotovora and E. chrysanthemi are responsible for soft rot diseases, affecting plants in the field and/or in storage. Thirty-one strains from Portugal and elsewhere were characterised by classical, fatty acid methyl ester (FAME) and molecular methods (MSP-PCR and BOX-PCR). Ten strains were identified as E. carotovora subsp. atroseptica, 10 as E. carotovora subsp. carotovora, and 11 as E. chrysanthemi by classical methods. Strains of E.c. subsp. carotovora and E. chrysanthemi were phenotypically, chemotaxonomically, and genetically highly variable. E. c. subsp. atroseptica strains isolated from Portuguese fields had low molecular variability, but FAME analysis revealed high phenotypic variability. Fatty acid profiles of the Portuguese strains were compared with 27 E. c. subsp. atroseptica profiles obtained from the Dutch Plant Protection Service (PD) collection. The Portuguese E. c. subsp. atroseptica strains clustered separately from PD E. c. subsp. atroseptica strains. However, the clusters are not distant enough for Portuguese strains to be included in separate subspecies. Therefore, these Portuguese E. carotovora subsp. atroseptica strains may constitute an ecotype occurring in Portugal.