A new PCR system for Agrobacterium tumefaciens detection based on amplification of T-DNA fragment.

The design of the PCR system presented in this work is based on the knowledge of the molecular character of the crown gall disease. The virulence of Agrobacterium tumefaciens requires the presence of a big (up to 235,000 bp) plasmid Ti (pTi-tumour inducing plasmid). This plasmid carries the so-called T-DNA fragment (T-DNA-transferred DNA), which integrates into cell chromosomes of the infected plants and subsequently changes the plant morphology nad metabolism. In cannot be excluded that after T-DNA integration the presence of Agrobacterium is not necessary for the development of pathological changes. Thus, T-DNA is the only sign that must be present both in virulent bacteria and in infected plants in any stadium of the disease and even before the infection. This is why T-DNA was chosen as the target region for PCR amplification. Primers flanking a 220 bp fragment of one of the conservative regions responsible for Agrobacterium pathogenicity, namely tms2 gene coding for indolacetamide amidohydrolase (the second step of auxin biosynthesis) were designed as the optimal for PCR amplification. The PCR amplification reactions were performed for matrixes isolated from cultures of reference strains giving one predicted product for each sample. First attempts of T-DNA detection in infected soils and plants were performed. We hope that the presented new PCR system for Agrobacterium tumefaciens detection will help to fight the crown gall disease in the nearest future.