IS-1327, A NEW INSERTION-LIKE ELEMENT IN THE PATHOGENICITY-ASSOCIATEDPLASMID OF ERWINIA-HERBICOLA PV GYPSOPHILAE

The pathogenicity-associated plasmid (pPATH) of Erwinia herbicola pv. gypsophilae was previously shown to be exclusively present in pathogen ic strains and to contain a gene cluster encoding phytohormone biosynt hesis. Sequence analysis of the DNA region located downstream from the cytokinin biosynthetic gene (etz) revealed homology to insertion sequ ences (IS) of the IS6 family. Southern blot analysis performed on plas mid DNA of E. herbicola pv, gypsophilae revealed the presence of six c opies of this insertion-like element, which was designated as IS1327. Only pathogenic strains contained IS1327 and restriction fragment leng th polymorphism was observed among gypsophila and beet pathovars of E. herbicola. Nonpathogenic deletion derivatives of pPATH contained fewe r copies of IS1327, suggesting its presence in the deleted region. One copy of IS1327 (IS1327-R) was located 2.8 kb downstream from the IS e lement adjacent to the etz (IS1327-L) in a direct repeat.