Challenges in Medicinal and Aromatic Plants DNA Barcoding-Lessons from the Lamiaceae

Abstract

The potential value of DNA barcoding for the identification of medicinal plants and authentication of traded plant materials has been widely recognized; however, a number of challenges remain before DNA methods are fully accepted as an essential quality control method by industry and regulatory authorities. The successes and limitations of conventional DNA barcoding are considered in relation to important members of the Lamiaceae. The mint family (Lamiaceae) contains over one thousand species recorded as having a medicinal use, with many more exploited in food and cosmetics for their aromatic properties. The family is characterized by a diversity of secondary products, most notably the essential oils (EOs) produced in external glandular structures on the aerial parts of the plant that typify well-known plants of the basil (Ocimum), lavender (Lavandula), mint (Mentha), thyme (Thymus), sage (Salvia) and related genera. This complex, species-rich family includes widely cultivated commercial hybrids and endangered wild-harvested traditional medicines, and examples of potential toxic adulterants within the family are explored in detail. The opportunities provided by next generation sequencing technologies to whole plastome barcoding and nuclear genome sequencing are also discussed with relevant examples.

Keywords: DNA barcoding; ITS region; Lamiaceae; Lavandula; Mentha; Ocimum; Thymus; medicinal plants.

Figure 2

Mintproducts market analysis [130] and phylogenetic relationship among the species.

Figure 1

Schematic representation of nrDNA region with ITS region’s primer (ITS1/ITS4) localization (arrows). ETS (External transcribed spacers).

Figure 3

Lavender products market analysis [180] and phylogenetic relationship among the species.

Figure 4

Basil products market analysis [199] and phylogenetic relationship among the species.

Figure 5

Oregano products market analysis [221] and phylogenetic relationship among the species.

Figure 6

Skullcap products, applications and phylogenetic relationship among the species of Scutellarioideae and other subfamilies of Lamiaceae.

Figure 7

Morphological similarities between Scutellaria and Teucrium.

Figure 8

Salvia products, applications and phylogenetic relationship among subgenera.