Genetic characterization of Plectranthus amboinicus (Lour.) using morphology and ITS sequences across eight Vietnamese provinces

Plectranthus amboinicus (Lour.) is a spice and medicinal vegetable with tenacious vitality, easy to grow, and able to thrive even in the shade, making it widely cultivated in Vietnam. This study aimed to evaluate the agronomic characteristics of 80 samples of Plectranthus amboinicus (Lour.) from 8 provinces, based on a morphological assessment of stem height, root length, and leaves, combined with molecular biology methods to determine genetic relationships using the Internal Transcribed Spacer (ITS) gene region sequencing. The results of the morphological characteristics of the plant samples showed variations in stem height, leaf length, leaf width, and root length; however, flowers and fruits showed little variation among samples. Samples collected from An Giang and Hau Giang provinces were relatively larger than those from other provinces. Phylogenetic analysis demonstrated a close genetic relatedness among Plectranthus amboinicus (Lour.) genotypes from the eight provinces, while exhibiting a genetic distance of 0.2970 from the control species, Mentha arvensis, an exotic species. Therefore, there were differences in the morphological characteristics of Plectranthus amboinicus (Lour.) among the samples. The amplified sequence of the ITS gene region of the experimental samples was approximately 600 bp in size, and sequencing results showed high similarity to to published Plectranthus amboinicus (Lour.) reference sequences.