Phylogenetic Analysis Based on DNA Barcoding and Genetic Diversity Assessment of Morinda officinalis How in Vietnam Inferred by Microsatellites

Morinda officinalis How is well-known as a valuable medicinal plant found in some regions of Vietnam. This species is mainly used for treating male impotence, irregular menstruation, and rheumatoid arthritis. This study aimed to identify the species of and genetic diversity in three M. officinalis populations: one each in Quang Binh (QB), Thua Thien Hue (TTH), and Quang Nam (QN). In this study, four DNA barcoding markers (ITS1, ITS2, matK, and rbcL) were used to identify the species and 22 microsatellite markers were applied for population structure and diversity analyses. The results showed that the sequences of gene regions studied in M. officinalis had a high similarity (>95%) to the ITS1, ITS2, matK, and rbcL sequences of M. officinalis on BLAST. Of the four DNA barcoding markers used, ITS1 and ITS2 showed higher efficiency in DNA amplification of M. officinalis. From this study, 27 GenBank codes were published on BLAST. The results also revealed high levels of genetic diversity in populations. The average observed and expected heterozygosity values were H(O) = 0.513 and H(E) = 0.612, respectively. The average F(ST) value was 0.206. Analysis of molecular variance (AMOVA) showed 70% variation within populations and 30% among populations. The population structure of M. officinalis inferred in STRUCTURE revealed that the optimum number of genetic groups for the admixture model was K = 2. These findings provided vital background information for future studies in the conservation of M. officinalis in both ex situ and in situ plans.