RAPD analysis of genetic diversity in Thuja koraiensis Nakai population

Thuja koraiensis Nakai belongs to the Cupressaceae family, which is an evergreen tree species celebrated for its durable wood. The branches, leaves, and seeds of the plant can be utilized as medicinal components, exhibiting properties such as hemostasis and cough relief. The volatile oil extracted from its branches and leaves functions as a spice with notable bacteriostatic effects. It is a rare and endangered protected species with ornamental, medicinal and aromatic characteristics. However, increasing attention to these resources has led to illegal logging and deforestation of wild T. koraiensis populations, resulting in a sharp decline in both the area and number of these populations, pushing the species to the brink of extinction. Urgent conservation efforts are imperative to protect this valuable species. To reveal the genetic diversity and genetic relationship of T. koraiensis Nakai, it is necessary to provide the basis for exploring the molecular mechanism and conservation of this endangered species. The study utilized Random Amplified Polymorphic DNA (RAPD) markers to analyze genetic diversity and genetic distance of T. koraiensis. The analyses were conducted at 8 distribution sites in Jilin Province, China. A total of 331 loci including 230 polymorphic loci, were amplified by 21 RAPD primers, and the percentage of polymorphic loci (PPL) was 69.49%. The average Nei’s genetic diversity index (H) was 0.1138, and the average Shannon Diversity Information index (I) was 0.1687. The genetic diversity of T. koraiensis is relatively low. The coefficient of genetic differentiation (Gst) among populations was 0.5418, indicating that the majority of genetic variation is partitioned among populations. The gene flow (Nm) between the populations was 0.4228. There was less gene exchange between groups, and the genetic diversity of the species was at a low level. The genetic distance among the 8 populations of T. koraiensis ranged from 0.1126 to 0.2734. Through cluster analysis based on these genetic distances, the 8 populations were classified into two distinct groups. The results showed that there were few polymorphic loci and a low genetic diversity in the population. Genetic diversity among populations was higher than within populations. Genetic differentiation mainly existed among populations, and gene flow was small. This might be an important reason for the endangered status of T. koraiensis.