Analysis of bacterial communities in the rhizosphere of transgenic rol ABC citrange Troyer: preliminary studies

Citrange Troyer, genetically modified by inserting rolABC genes, was characterized by a change in the growth habit. Three transgenic clones and four wild type plants have been grown in pots for two years. Morphological and physiological modifications were detected, including dwarfing effect and increase of root system density. Our objective was to evaluate the bacterial diversity in the rhizosphere of rolABC citrange Troyer by using pheno-typical testing (BIOLOG) and 16S rDNA gene-based mo-lecular analysis (ARDRA; DGGE) to monitor rhizosphere soil. Autotrophic ammonia oxidising bacteria, studied by ARDRA fingerprints, only showed minimal modifications between transgenic and wild type clones. BIOLOG data and DGGE profiles showed that the structure of the bacte-rial rhizosphere communities of rolABC citrange Troyer was minimally altered. Moreover, the eubacterial DGGE profiles reflected strong seasonal population shifts in the bacterial rhizosphere community.