Types of resistance of grapevine varieties to isolates of Agrobacterium tumefaciens biotype 3

Eight grapevine varieties representing four susceptibility patterns were infected with octopine-,nopaline- and vitopine-inducing isolates of Agrobacterium tumefaciens (Smith and Townsend) Conn biotype 3. These varieties showed three different types of resistance. (I) In the first category the wound calluses contained the appropriate opine following inoculation. (II) Resistant hybrids of the 28 19 group also formed wound calluses after infection with nopaline-inducing isolates but nopaline was not detectable in these tissues. (III) Infections with vitopine-inducing isolates resulted in tissue necrosis at the wound sites of certain varieties. Co-inoculations with vitopineand octopine- or nopaline-inducing isolates did not result in tumour formation on varieties Kunleány and A2 11 which are susceptible to octopine- and/or nopaline-inducing isolates of A. tumefaciens.