VIEW ARTICLE

Genetics

Genetic Factors Controlling the Host Range of Agrobacterium tumefaciens. V. C. Knauf, Department of Microbiology and Immunology, University of Washington, Seattle 98195; C. G. Panagopoulos(2), and E. W. Nester(3). (2)Institut Phytopathologique Benaki, Kiphissia, Athens, Greece; (3)Department of Microbiology and Immunology, University of Washington, Seattle 98195. Phytopathology 72:1545-1549. Accepted for publication 29 April 1982. Copyright 1982 The American Phytopathological Society. DOI: 10.1094/Phyto-72-1545.

Host range differences were observed among 34 isolates of Agrobacterium tumefaciens from grapevine by virulence testing on eight different plant hosts. Six different host range patterns were evident. In 20 of 22 cases, a laboratory-derived strain of Agrobacterium carrying the virulence (Ti) plasmid from a natural isolate expressed the same host range as the natural isolate of A. tumefaciens. Thus, the Ti plasmid is the primary determinant of host range whether the host range is wide or narrow. Two wild-type strains were virulent on two plant hosts on which other strains containing the same or similar Ti plasmids were avirulent. These data indicate that the bacterial chromosome can affect some host range properties. Moreover, the response on grapevine depends on the cultivar of grapevine tested; a given strain of A. tumefaciens may induce tumors on some, but not all, cultivars of Vitis vinifera.