Phylogenetic analyses and species delimitation in the section Corydalis (Papaveraceae) based on chloroplast markers

The genus Corydalis (Papaveraceae), which is distributed in temperate regions of the northern hemisphere, has been taxonomically studied mainly on the basis of morphological and molecular genomic information. In the present study, 14 species that belong to the Korean section Corydalis were collected in South Korea and phylogenetically analyzed using four chloroplast genomic regions, which include matK, rbcL, rpL16 genes and the trnG intron. The author tried to include the nuclear Internal Transcribed Spacer (ITS) region in the phylogenetic analysis; however, multiple PCR bands and various band sizes observed led to the conclusion that the ITS region is not suitable for the phylogenetic study of Corydalis. When the four chloroplast genomic regions were separately analyzed, different levels of resolution for species delimitation were observed, and in most cases the resolution levels were quite low. When matK and rpL16 were concatenated, the highest resolution for species delimitation was observed. However, when other regions were added to this concatenated region to improve the resolution, the resolution decreased, which was in contrast to the author's expectation and deserves further analysis. At the same time, the author observed inconsistencies between the previously established taxonomy based on morphology and the molecular phylogenies in the present study. This discrepancy needs to be addressed in further detail, so that the taxonomy of the genus Corydalis can fully incorporate both morphology and molecular genomic information. Overall, the present study provides insights into the taxonomy of Corydalis, and clearly demonstrates that proper combinations of chloroplast markers can lead to successful discrimination of the species in this genus. Indeed, this study suggests ways to better utilize phylogenetic analyses and species delimitation in this interesting and complicated taxon. Since Corydalis is taxonomically challenging and widely used as medicinal plants in Asia, this study can be a valuable source of information on this genus.