Phylogenetic analysis based on chloroplast genome uncover evolutionary relationship of all the nine species and six cultivars of tree peony

Industrial development of tree peony is limited by the genetic background variation, fuzzy genetic relationships, and the large and complex genome. The chloroplast genome which extremely conservative in structure is a perfect research method for investigation of genetic relationship identification. The study of the chloroplast genome of tree peony, including structural characteristics, phylogenetic relationships, and population genetics, is of importance. In this study, a total of nine species and six cultivars of tree peony were used to determine the chloroplast genome difference. Tree peony dendrogram was obtained using complete sequences of the chloroplast genome. Chloroplast genome of tree peony with whole length of 152, 519 bp and 154, 405 bp has 116 genes in total, of which covering 82 protein coding genes, 30 tRNA, and 4 rRNA. Gene types, codon usage and repeat sequence distribution were highly consistent in tree peony species and cultivars reflecting a high conservation chloroplast genome. The phylogenetic tree was largely consistent with the available taxonomy of the major tree peony taxa. Further verification needs to be done to identify the accurate phylogenetic location of certain basic taxons. It is anticipated that the results will furnish us with a basis for developing available genetic resources, molecular marker-assisted breeding and variety identification of tree peony.