Classification of Chinese Medicinal Tree Peony Cultivars Based on Chloroplast DNA Sequences

Abstract

Tree peonies are deciduous subshrubs of the Paeonia sect. Moutan of the Paeoniaceae. They have been used as medicine for more than 2000 years in China. In contrast with the traditional knowledge of one medicinal lineage, cpDNA sequences revealed that the cultivars of Chinese medicinal tree peonies were classified into four lineages. P. ‘Xiang Dan’ (from Hunan production area) and P. ostii (from Anhui production area) belong to two different lineages, and P. ‘Hu Lan’ (from Hubei production area) belongs to another lineage. P. ‘Jinpao Hong’, ‘Jianshi Fen’ and ‘Taiping Hong’, with a sympatric distribution in Hubei Province and Chongqing municipality, together formed a different lineage by sharing a single cpDNA genotype, although they have certain phenotypic differences. A taxonomic key to the Chinese medicinal tree peony cultivars was compiled for identification. The highest nucleotide difference (0.004) occurred between P. ostii and the rest cultivars (such as P. ‘Jinpao Hong’, ‘Jianshi Fen’, ‘Taiping Hong’ and P. ‘Xiang Dan’). The significant genetic differentiation among the medicinal cultivars suggested that it is necessary to conduct an intensive evaluation on the core germplasm resources in order to improve conservation, rational utilization, quality control, breeding and development of medicinal tree peony industry.