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American Journal of Plant Physiology

Year: 2006  |  Volume: 1  |  Issue: 2  |  Page No.: 142 - 150

Characterization of Agrobacterium tumefaciens Strains Isolated from Brazilian Plant Species

Flavia T. H. Pacheco, M. Estela Silva-Stenico, Darcy M. da Silva (in memorian) and Marie-Anne Van-Sluys


The morphology and development of Brazilian isolates-induced tumors were studied in vitro and in vivo using marker plants, which are highly susceptible to Agrobacterium sp. infection. Tumor tissues were submitted to biochemical analysis to identify opine compounds and bacterial isolates were tested to their ability to utilize different opine types. 16S rDNA region and Intergene Space Sequence (IGS) of these isolates were amplified, producing a single fragment of 1,500 and 2,600 bp, respectively. From Ti plasmid, nopaline synthase (nos) region was amplified for all isolates, with a fragment of 256 bp. The results from test-plants showed that tumor phenotype characteristics, such as form (wart and root), color and post-inoculation appearance period were distinct for each isolate. Bacteriological tests allowed to classify all the eight isolates as hosting a nopaline type Ti plasmid. Sequence analysis of PCR products from 16S rDNA region showed that these Agrobacterium isolates have high sequence similarity to previously described A. tumefaciens isolates, belonging most of them to biovar 1.

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