Evaluation of ITS2 for intraspecific identification of Paeonia lactiflora cultivars

Herbaceous peony (Paeonia lactiflora Pall.) is an important ornamental and medicinal plant. DNA barcodes can reveal species identity via the nucleotide diversity of short DNA segments. In this study, two main candidate DNA barcodes (ITS2 and psbA-trnH) were tested to identify twenty-one cutting cultivars of P. lactiflora and their wild species. The efficacy of the candidate DNA barcodes was assessed by PCR amplification, sequence quality, sequence diversity, rate of correct identification, and phylogenetic analysis. ITS2 was easy to be amplified and sequenced among the samples. The identification by Blastn and phylogenetic analysis was 95.4% and 63.6%, respectively. For psbA-trnH, the presence of poly A-T led to sequencing failure which limited its use as DNA barcode candidate. Moreover, the authentic efficiency of psbA-trnH was lower than ITS2. The results showed that ITS2 is suitable as a candidate DNA barcode for the intraspecific identification of P. lactiflora cultivars.