HrpW of Erwinia amylovora, a new Hrp‐secreted protein

Erwinia amylovora strain CFBP1430 secretes a protein called HrpW in a Hrp-dependent manner. HrpW was detected in culture supernatant of the wild-type strain grown on solid inducing hrp medium. This protein shares structural similarities with elicitors of the hypersensitive response such as HrpN of Erwinia amylovora and PopA of Ralstonia solanacearum. Furthermore, the C-terminal region of HrpW is homologous to class III pectate lyases. An hrpW mutant is as aggressive as the wild-type strain on pear and apple seedlings. It elicits the hypersensitive response on tobacco at a lower concentration than the wild-type strain.