Detection and characterization of Pseudomonas syringae pv. actinidifoliorum in kiwifruit in Spain

Aims: Bacterial canker of kiwifruit caused by Pseudomonas syringae pv. actinidiae (Psa) is currently the major threat to its commercial production worldwide. In 2011, the most virulent type (Psa3) was detected for the first time in Northwest-Spain, in the province of Pontevedra. In 2013 surveys, leaves and flower buds with mild symptoms were observed in Actinidia deliciosa `Hayward' vines in an orchard at the province of A Coruna, suggesting the presence of P. syringae pv. actinidifoliorum (Psaf). Methods and Results: Isolates obtained from such orchard were characterized by morphological, biochemical and physiological tests, fatty acids (FA) profile and molecular tests (PCR, BOX-PCR, duplex PCR, multiplex PCR, real-time PCR, PCR-C, phytotoxins, housekeeping and effector genes). Pathogenicity tests were also carried out on plants and fruits of A. deliciosa `Hayward' and on different cultivated plants and fruits. Results demonstrated the presence of P. syringae pv. actinidifoliorum in Spain. Conclusions: The work provides new information on the pathovar P. syringae pv. actinidifoliorum, which has only been found previously in New Zealand, Australia and France. Significance and Impact of Study: The results are relevant for taxonomy of isolates of P. syringae from kiwifruit, especially those of low virulence not belonging to pathovar actinidiae.