Molecular identification of species of Physalis (Solanaceae) using a candidate DNA barcode: the chloroplast psbA–trnH intergenic region

Physalis L., an important genus of the family Solanaceae, includes many commercially important edible and medicinal species. Traditionally, species identification is based on morphological traits; however, the highly similar morphological traits among species of Physalis make this approach difficult. In this study, we evaluated the feasibility of using a popular DNA barcode, the chloroplast psbA–trnH intergenic region, in the identification of species of Physalis. Thirty-six psbA–trnH regions of species of Physalis and of the closely related plant Nicandra physalodes were analyzed. The success rates of PCR amplification and sequencing of the psbA–trnH region were 100%. MEGA V6.0 was utilized to align the psbA–trnH sequences and to compute genetic distances. The results show an apparent barcoding gap between intra- and interspecific variations. Results of both BLAST1 and nearest-distance methods prove that the psbA–trnH regions can be used to identify all species examined in the present study. In addition, phylogenetic analysis using psbA–trnH data revealed a distinct boundary between species. It also confirmed the relationship between species of Physalis and closely related species, as established by previous studies. In conclusion, the psbA–trnH intergenic region can be used as an efficient DNA barcode for the identification of species of Physalis.