DNA-based herbal teas authentication: a ITS2 and psbA-trnH multi-marker DNA metabarcoding approach

Medicinal plants have been widely used in traditional medicine due to their therapeuticproperties. Although they are mostly used as herbal infusion and tincture, employment asingredients of food supplements is increasing. However, fraud and adulteration are widespreadissues. In our study, we aimed at evaluating DNA metabarcoding as a tool to identify productcomposition. In order to accomplish this, we analyzed fifteen commercial products with DNAmetabarcoding, using two barcode regions: psbA-trnH and ITS2. Results showed that on average,70% (44–100) of the declared ingredients have been identified. The ITS2 marker appears toidentify more species (n = 60) than psbA-trnH (n = 35), with an ingredients' identification rate of52% versus 45%, respectively. Some species are identified only by one marker rather than theother. Additionally, in order to evaluate the quantitative ability of high-throughput sequencing(HTS) to compare the plant component to the corresponding assigned sequences, in thelaboratory, we created six mock mixtures of plants starting both from biomass and gDNA. Ouranalysis also supports the application of DNA metabarcoding for a relative quantitative analysis.These results move towards the application of HTS analysis for studying the composition of herbalteas for medicinal plants' traceability and quality control.