Forensic application of DNA barcoding in the identification of commonly occurring poisonous plants.

Exposure to poisonous plants is hazardous to health; thus, reliable species identification is required to decide the most appropriate treatment. Since ingested plants are too much degraded for visual observation, DNA barcoding can be used as a molecular tool for species identification. Considering the universal primers, PCR and sequencing success rate, and diversity of the poisonous plants, the rbcL DNA marker was selected for molecular identification. A reference DNA barcode library for 100 poisonous plant species was created using rbcL DNA barcodes. For the poisonous plants represented in the library, 100% and 89% species differentiation was observed at the genus and species level, respectively. All the undifferentiated species were congeneric species. Mapping the metabolites of the poisonous plants to the DNA based phylogenetic tree indicated that the phylogenetically related species also had related toxic compounds. Therefore, genus-level identification may be sufficient in the practical application of DNA barcoding in poisoning cases. We conclude that rbcL can be used as a primary marker, and if required, ITS2 or trnH-psbA may be used as a secondary marker to identify the poisonous plants. The present study provides the foundation to develop a reliable molecular method to identify the poisonous species from the vomit samples of poisoning cases.