Physiological, biochemical and molecular analyses of an Italian collection of Agrobacterium tumefaciens strains.

Physiological, biochemical and molecular characteristics of Agrobacterium tumefaciens strains isolated in Italy from different host plants were analysed. Diseased plants were collected from several nurseries located in nine different regions. Out of 1293 strains isolated from 12 fruit tree and six ornamental plant species, a group of 120 strains was chosen as representative of the whole collection. The majority of the strains were biovar 2, agrocin 84 sensitive, and were isolated from stone fruit trees. Most of the strains identified as biovar 1 were isolated from ornamental plants and were insensitive to A. radiobacter antagonistic strain K84. Some strain that were isolated from Euonymous spp., Prunus GF677 and Pyrus communis tumors could not be allocated to any of the three Agrobacterium biovars. PCR-RFLP of the rrs gene plus the intergenic spacer was used for strain fingerprinting and characterization. Results showed a wide genetic variability within the biovar 1 strains and homogeneity within the biovar 2 group. Biovar 2 strains from Sardinia were highly variable and differed from the biovar 2 strains isolated from the other regions of Italy.