Identification of hrp Genes, Encoding Harpin Protein, in Pseudomonas avellanae (Psallidas) Janse et al.

We have identified hrp genes, encoding harpin proteins, of two strains of Pseudomonas avellanae originating, from the Latium and Piedmont regions, respectively. These strains belong to two populations differing in phenotypic, molecular and pathogenic characteristics. For this purpose, hrpZ primers of Pseudomonas syringae pv. syringae strain 61 (hrpZPss) and hrpW primers of Pseudomonas syringae pv. tomato strain DC3000 (hrpWPst) were used for amplification, by polymerase chain reaction, of presumptive hrpZ and hrpW genes in P. avellanae strains. The hrpW primers were able to amplify, in both P. avellanae strains, a 1.2 kb fragment corresponding in size to the hrpW gene, whereas hrpZ primers did not give amplification products. To obtain information about this gene, a hrpZ fragment of about 500 nucleotides was amplified, using sequence‐degenerate oligonucleotides. The nucleotide sequences of these amplified hrp genes of P. avellanae are reported and compared with the known sequences of these genes reported in the GenBank‐EMBL Data Bank.