Research Notes New Pathogenicity Loci in Erwinia stewartii Identified by Random Tn5 Mutagenesis and Molecular Cloning. D. L. Coplin. Department of Plant Pathology, The Ohio State University, Columbus, OH 43210-1087. R. D. Frederick, and D. R. Majerczak. Department of Plant Pathology, The Ohio State University, Columbus, OH 43210-1087.. MPMI 5:266-268. Accepted 30 January 1992. Copyright 1992 The American Phytopathological Society.

Pseudomonas aeruginosa plasmid pMO75 was used as a delivery system to introduce random Tn5 mutations into the genome of Erwinia stewartii. Nineteen avirulent mutants were identified by screening for loss of wilt induction and water-soaking (Wts) on corn seedlings. Five new wts mutations were mapped to the left of wtsA, thereby enlarging the wts gene cluster to approximately 28 kb. Four Wts‾ mutations appeared to be unlinked to the wts cluster and may represent new pathogenicity loci.