Comparative analysis of chloroplast genomes of Sanguisorba species and insights into phylogenetic implications and molecular dating

Sanguisorba is a small genus, which consists of about 15 species widely distributed in North America and Eurasia. Previous studies on Sanguisorba are useful for understanding of phylogeny and chloroplast (cp) genome evolution of Sanguisorba. However, the cp genome resources of Sanguisorba are still limited, and the phylogeny and molecular dating for Sanguisorba and its relatives still need further explored. Here, we reported four cp genomes of Sanguisorba and conducted comparative analysis of the four Sanguisorba cp genomes plus five previously published ones. The nine cp genomes of Sanguisorba have typical tetrad quadripartite structure, with a total length of 154 282 to 155 730 bp, and their gene content, gene structure, and gene order are relatively conservative. The analysis of single copy (SC)/inverted repeat (IR) boundaries shows very slight boundary differences in Sanguisorba cp genomes. Eight variation hotspots were screened as excellent candidate markers of Sanguisorba. Phyloge...