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.