CHARACTERIZATION OF ANTAGONISTIC ROOTASSOCIATED FLUORESCENT PSEUDOMONADS OF TRANSGENIC AND NONTRANSGENIC CITRANGE TROYER PLANTS
G. Cirvilleri, S. Spina, G. Scuderi, A. Gentile, A. Catara
To study the influence of rolABC Troyer citrange plants on potentially beneficial root-associated bacteria, transgenic and non-transgenic plant lines were monitored over the course of one year. Culturable bacterial populations were not significantly different between rolABC and wild type lines, whereas the population of fluorescent pseudomonads varied according to the plant lines and the date of sampling. A total of 321 representative fluorescent pseudomonads were investigated to determine antagonistic activity against Fusarium solani and Phoma tracheiphila, and two different antagonistic groups were identified. IAA-producing Pseudomonas fluorescens strains were well distributed among transgenic and non-transgenic plant lines. A subset of 42 representative antagonistic P. fluorescens strains, characterized by ARDRA and ERIC-PCR, showed a high degree of DNA heterogeneity. Four main groups were identified. Three groups were heterogeneous and contained isolates from transgenic and non-transgenic plant lines whereas one group was homogeneous and included only strains from transgenic lines belonging to the same antagonistic group. On the whole, the fluorescent populations isolated from the rolABC lines showed some differences from those isolated from wild types, and a partial correlation was observed between grouping of strains based on antagonistic activity and on ERIC-PCR fingerprints and the transgenic character of the plants.