CHARACTERIZATION AND PATHOGENICITY OF BACTERIA FROM SHOOT TIPS OF THEGLOBE ARTICHOKE (CYNARA-SCOLYMUS L)

Bacteria have been isolated from shoot tips of symptomless globe artic hoke plants. These were identified as Pseudomonas fluorescens, Pseudom onas marginalis, Pseudomonas spp., Serratia liquefaciens, Enterobacter agglomerans/Erwinia, Agrobacterium radiobacter, an unidentified membe r of Rhizobiaceae and another classified in the ''corynebacteria'' gro up. The most frequently isolated species was P. fluorescens, biovars I I and III. The endogenous character of these bacteria was studied in p lants growing in vitro and in the open held. P. fluorescens, P. margin alis, S. liquefaciens and E. agglomerans/Erwinia caused symptoms in pl ants growing in vitro, but only P. fluorescens biovar II and P. margin alis produced symptoms in plants growing in open fields. Differences i n pathogenicity were observed on inoculated plants growing in vitro or in the open field. This suggests that several endophytic bacterial sp ecies may be responsible for the high levels of contaminants found dur ing the micropropagation of globe artichoke.