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Agrobacteria were previously isolated from tumors developing on branches and aerial and hypogeous roots of weeping fig plants in Italy and in The Netherlands. A representative group of 48 strains was analyzed by PCR–RFLP of 16S and 16S + IGS ribosomal regions, PCR–RFLP of six Ti plasmid (pTi) regions and characterized for plasmid content. Two groups of agrobacteria were separated by cluster analysis of PCR–RFLP profiles of rrsgene: seventeen strains were similar to the new species Agrobacterium larrymoorei, while the remaining strains were included within the agrobacterium biovar 1 group. Sixteen different plasmid profiles from one to five plasmids were observed. In addition, 21 ribotypes and 20 pTi structures were arranged in many different combinations, showing that fig agrobacteria were characterized by a wide heterogeneity. A general lack of correlation between strain ribotypes and plasmid content was observed.

Physiological, biochemical and molecular characteristics of Agrobacterium tumefaciensstrains 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 (82.5%), 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. radiobacterantagonistic strain K84. Some strains that were isolated from Euonymusspp, PrunusGF 677 and Pyrus communis(pear) OHF tumours could not be allocated to any of the three Agrobacteriumbiovars. PCR-restriction fragment length polymorphism of the rrsgene plus the intergenic spacer was used for strain fingerprinting and characterisation. 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.