Changes in properties of phytopathogenic bacteria effected by plasmid pRD1.

Transfer of plasmid pRD1 from Escherichia coli K 12J62 -1 to phytopathogenic bacteria, Agrobacterium tumefaciens, Xanthomonas beticola and Erwinia carotovora subsp. carotovora caused changes in conjugant properties not determined by the plasmid and the emergence of the properties not present in the parent strains. Clones have been obtained with intermediate properties between donor and recipient, including those with altered or lost virulence.