Catmint (Nepeta nuda L.) phylogenetics defined by nuclear and chloroplast DNA barcodes

Abstract

Nepeta nuda L. (Lamiaceae) is a medicinal plant with a wide distribution in Europa and Asia. In Bulgaria, N. nuda is also known as “naked (or hairless) catmint”, which likely refers to the naked or sparse short hairy stem and leaves. This study aims to generate DNA barcodes for precise genetic discrimination and determination of phylogenetic position of the plant among other Nepeta species. To achieve this goal, we applied the DNA barcoding technique based on conserved nuclear (internal transcribed spacer/ITS) and chloroplast (rbcL, matK, trnH) DNA regions. The generated DNA barcode sequences were submitted to the Barcode of Life Data System (BOLD) database (https://www.boldsystems.org; accession number BUL002-22). The obtained N. nuda DNA barcodes and corresponding sequences of other Nepeta species available in the BOLD and NCBI database were utilized for taxonomic classification. ITS-derived sequences for Nepeta species were the most enriched in the database, and DNA fragments matching 47 Nepeta species were selected for construction of phylogenetic tree. The results show that N. nuda is clustered in a subclade together with N. sheilae, N. deflersiana, N. isaurica, N. congesta, N. heliotropifolia, N. schiraziana and N. cataria. The information in BOLD was also retrieved for rbcL and matK, and corresponded to 15 and 10 different Nepeta species, respectively. For trnH, only NCBI sequences corresponding to 6 different Nepeta species were found. Тhe three chloroplast markers highlighted the close relation of N. nuda to N. italica, N. tuberosa, N. cataria, N. grandiflora and N. hemsleyana. In conclusion, we suggest a DNA barcode system for genetic discrimination of N. nuda, which could assist its accurate taxonomic characterization.