Detection of tumorigenic rhizobia in asymptomatic peach plants by PCR.

At present the only method for the detection of Rhizobium radiobacter and R. rhizogenes (ex Agrobacterium tumefaciens) in plants is by isolating the bacteria on selective medium and testing them in vivo for pathogenicity. This procedure is time-consuming and not appropriate for detecting low concentrations of these agrobacteria. In this study a protocol was developed for detecting tumorigenic agrobacteria in the stem and root tissues of artificially inoculated peach plants. DNA was extracted from the plant tissues by a rapid procedure and then a 246 bp sequence of the vir region of the pTi was amplified by PCR. The target sequence was found in all stem and root samples of asymptomatic peach plants, and was evidenced in all the samples analyzed showing the effectiveness and reliability of the method.