Abstract
BACKGROUND: Many species of the genus Rosa have been used as ornamental plants and traditional medicines. However, industrial development of roses is hampered due to highly divergent characteristics. METHODS: We analyzed the chloroplast (cp) genomes of Rosa laevigata, R. rugosa and R. canina, including the repeat sequences, inverted-repeat (IR) contractions and expansions, and mutation sites. RESULTS: The size of the cp genome of R. laevigata, R. rugosa and R. canina was between 156 333 bp and 156 533 bp, and contained 113 genes (30 tRNA genes, 4 rRNA genes and 79 protein-coding genes). The regions with a higher degree of variation were screened out (trnH-GUU, trnS-GCU, trnG-GCC, psbA-trnH, trnC-GCA,petN, trnT-GGU, psbD, petA, psbJ, ndhF, rpl32,psaC and ndhE). Such higher-resolution loci lay the foundation of barcode-based identification of cp genomes in Rosa genus. A phylogenetic tree of the genus Rosa was reconstructed using the full sequences of the cp genome. These results were largely in accordance with the current taxonomic status of Rosa. CONCLUSIONS: Our data: (i) reveal that cp genomes can be used for the identification and classification of Rosa species; (ii) can aid studies on molecular identification, genetic transformation, expression of secondary metabolic pathways and resistant proteins; (iii) can lay a theoretical foundation for the discovery of disease-resistance genes and cultivation of Rosa species.