Complete Plastome of Three Korean Asarum (Aristolochiaceae): Confirmation Tripartite Structure within Korean Asarum and Comparative Analyses

The genus Asarum (Aristolochiaceae) is a well-known resource of medicinal and ornamental plants. However, the taxonomy of Korean Asarum is ambiguous due to their considerable morphological variations. Previously, a unique plastome structure has been reported from this genus. Therefore, we investigated the structural change in the plastomes within three Korean Asarum species and inferred their phylogenetic relationships. The plastome sizes of Asarum species assembled here range from 190,168 to 193,356 bp, which are longer than a typical plastome size (160 kb). This is due to the incorporation and duplication of the small single copy into the inverted repeat, which resulted in a unique tripartite structure. We first verified this unique structure using the Illumina Miseq and Oxford Nanopore MinION platforms. We also investigated the phylogeny of 26 Aristolochiaceae species based on 79 plastid protein-coding genes, which supports the monophyly of Korean Asarum species. Although the 79 plastid protein-coding gene data set showed some limitations in supporting the previous classification, it exhibits its effectiveness in delineating some sections and species. Thus, it can serve as an effective tool for resolving species-level phylogeny in Aristolochiaceae. Last, we evaluated variable sites and simple sequence repeats in the plastome as potential molecular markers for species delimitation.