Phylogenetic and Comparative Analyses of Complete Chloroplast Genomes of Chinese and (Adoxaceae).

Phylogenetic analyses of complete chloroplast genome sequences have yielded significant improvements in our understanding of relationships in the woody flowering genus (Adoxaceae, Dipsacales); however, these relationships were evaluated focusing only on species within Central and South America and Southeast Asia. By contrast, despite being a hotspot of diversity, phylogenetic relationships of species in China are less well known. Here, we characterized the complete chloroplast (cp) genomes of 21 species endemic to China, as well as three species. These 24 plastomes were highly conserved in genomic structure, gene order and content, also when compared with other Adoxaceae. The identified repeat sequences, simple sequence repeats (SSRs) and highly variable plastid regions will provide potentially valuable genetic resources for further population genetics and phylogeographic studies on and . Consistent with previous combined phylogenetic analyses of 113 species, our phylogenomic analyses based on the complete cp genome sequence dataset confirmed the sister relationship between and the --- group, the monophyly of four recognized sections in (i.e., sect. , sect. , sect. and sect. ) and the nonmonophyly of sect. and sect. . Additionally, our study confirmed the sister relationships between the clade Valvatotinus and sect. , as well as between sect. and the - group. Overall, our results clearly document the power of the complete cp genomes in improving phylogenetic resolution, and will contribute to a better understanding of plastome evolution in Chinese Adoxaceae.