Bar-HRM traceability of plants in food and medicine
Illegal collection and trade accelerate plant extinction and accounts for economic losses. Species of restricted distribution are affected disproportionately and require special conservation measures. The same applies to natural hybrids, due to their unique characteristics. Substitution of wild species, due to misidentification, can lead to severe adverse reactions. Poisonous plants can cause a variety of severe intoxications. Food adulteration harms the consumer in many ways. Based on the above, there is a need for efficient identification for edible, toxic, and endangered plant species.
Barcoding is an important tool towards the solution of traceability issues. Plant.ID is a collaborative network within Europe and addresses the challenges of plant identification in 15 different projects. We focus on common edible, poisonous, allergenic and pharmaceutical plants of the Greek flora. Through sequencing of barcoding regions and metabarcoding techniques, specific barcoding markers will be developed to be used either with PCR and/or with the High Resolution Melting Analysis for species-specific identification.
In the first part within this project, seventy-one herbal medicinal products were randomly purchased throughout Greece and analyzed using metabarcoding to identify species. The aim was to investigate possible adulteration and assess the ability of metabarcoding for plant based product authentication. Of the detected species in our analyses we found species that were not listed on the product labels. This indicates a high level of adulteration and/or contamination during processing and distribution. We also identified the presence of toxic species, as major ingredients of two herbal mixtures for medicinal purposes. The detection of the latter two species was also confirmed through Bar-HRM analysis.
The study revealed a need for stricter quality control of herbal products, especially because of the presence of toxic species. Low fidelity was found to be an issue, also in short chains of commercialization. We state that standardization of protocols is necessary before DNA metabarcoding can be implemented as a routine analytical approach and approved by competent authorities for use in a regulatory framework. Also, the availability of a rich and reliable DNA reference database is a prerequisite for successful implementation.
Impacts and weaknesses
The presence of toxic plant species in herbal products can pose serious health problems. Unexperienced pickers collecting edible plants in the field are particularly sensitive (Cornara et al., 2018). The harvest of salep orchids in Greece are threatening the natural orchid populations of Northern Greece (Kreziou et al., 2015). Fast and efficient species-specific detection methods for Greek orchids is required for biodiversity conservation.
The standardization of protocols is necessary before DNA metabarcoding can be implemented as a routine analytical approach and approved by competent authorities for use in a regulatory framework. Also, the availability of a rich and reliable DNA reference database is a prerequisite for successful implementation.