Comparative Plastomics of Plantains (, Plantaginaceae) as a Tool for the Development of Species-Specific DNA Barcodes.

(plantains, Plantaginaceae) is a cosmopolitan genus including over 250 species used as functional foods, forage, and traditional medicine. Among them, is commonly used as an ingredient of herbal products, but the close similarity to other species can cause misidentifications with potentially serious consequences for product safety/quality. To test the possibility of developing species-specific barcoding markers, we de novo assembled plastome sequences of individuals of , , , and . These genomes were characterized in comparison with both previously sequenced conspecific accessions and other publicly available plastomes, thus providing an assessment of both intraspecific and interspecific genetic variation in plastomes. Additionally, molecular evolutionary analyses indicated that eleven protein-coding genes involved in different plastid functions in plastomes underwent positive selection, suggesting they might have contributed to enhancing species' adaptation during the evolutionary history of . While the most variable mutational hotspots in plastomes were not suitable for the development of species-specific molecular markers, species-specific polymorphisms could discriminate from its closest relatives. Taken together, these results highlight the potential of plastome sequencing for the development of molecular markers to improve the identification of species with relevance in herbal products.