In-field detection and quantification of extracellular DNA

The key-role of transformation in evolutionary terms, justifies to continue the investigation on the fate of extracellular DNA in soil. To study the persistence of the extracellular DNA fraction in environmental substrates, the target DNA must be extracted and purified and must contain a unique sequence for specific detection of the introduced DNA. DNA-extraction protocols for environmental samples, such as soil, sediment, and water, are available but are mainly designed to extract total DNA. We applied an extraction method to recover extracellular DNA from rhizosphere soil and to specifically detect a target DNA, belonging to the bt-maize event MON810, directly in field via real-time PCR. This technique is known to be a sensitive tool for rapid and specific detection of target nucleic acids. The analyses of the extracellular DNA fraction allowed the specific monitoring of the plant DNA released by rhizodeposition and by damaged vegetal tissues, excluding the portion inside the intact plant tissues. And this is the peculiar aspect of this work, to monitor the extracellular fraction of soil DNA, the one involved in movements in the soil-water solution and in the transfer of genetic information during evolution.