Draft whole genome sequence analyses on Pseudomonas syringae pv. actinidiae hypersensitive response negative strains detected from kiwifruit bleeding sap samples

Kiwifruit bleeding sap samples, collected in Italian and Chilean orchards from symptomatic and asymptomatic plants, were evaluated for the presence of Pseudomonas syringae pv. actinidiae, the causal agent of bacterial canker. The saps were sampled during the spring of both hemispheres, before the bud sprouting, during the optimal time window for the collection of an adequate volume of sample for the early detection of the pathogen, preliminarily by molecular assays, and then, through its direct isolation and identification. The results of molecular analyses showed more effectiveness in the P. syringae pv. actinidiae detection, when compared to those of microbiological analyses through the pathogen isolation on the nutritive and semi-selective media selected. The bleeding sap analyses allowed the isolation and identification of two HR negative and hypovirulent P. syringae pv. actinidiae strains from different regions in Italy. Moreover, MLSA and WGS were carried out on selected Italian and Chilean P. syrin...