First Report of Pseudomonas syringae pv. actinidiae on Kiwifruit Pollen from Argentina

Abstract

During last years, in Mar del Plata (Argentina) area, many kiwifruit orchards composed by only male plants (Actinidia deliciosa cv. Chieftain) have been established for pollen production and commercialization, since the country was considered unaffected by Psa. When mature, the anthers are detached and dried, and grains of pollen collected with a portable cyclonic pollen collector. Then, routine controls aimed to assess the risk of infection by Pseudomonas syringae pv. actinidiae (Psa), the causal agent of kiwifruit bacterial canker (Takikawa et al., 1989), are carried out by plating 1 gram aliquots of pollen on semi-selective medium (modified KB) and incubating plates for 48-72 h at 27 °C. During one of these controls, in February 2015, some bacterial colonies with morphological features similar to Psa were detected. After purification, four of them (labeled as Arg1.1 to Arg2.3) were found to be gram negative, non-fluorescent, positive for levan production, and caused hypersensitive response on tobacco. ...