Presence of the effector gene hopA1 in strains of Pseudomonas syringae pv. actinidiae isolated from France and Italy

Abstract

Pseudomonas syringae pv. actinidiae (Psa) causes bacterial canker of kiwifruit, a disease that had limited economic impact in Italy before the outbreak of 2009. The strains isolated from Italy since 2008 have different characteristics to those isolated in Japan or Korea or those isolated earlier than 2008 in Italy. This study showed that strains of Psa isolated from France had the cts haplotype I and a BOX-PCR electrophoretic pattern similar to that of strains isolated from Italy after 2008. The effector gene hopA1, which was found previously by PCR to be present only in the strains of the cts haplotype I, was also present in other strains of Psa isolated from Italy. If this effector plays a role in the interaction between Psa and kiwifruit, then the difference in virulence observed between strains of different cts haplotypes cannot be attributed to the presence of this effector.