Comparative Analysis of the Complete Chloroplast Genome of MainlandAster spathulifolius and Other Aster Species

Aster spathulifolius, a common ornamental and medicinal plant, is widely distributed in Korea and Japan, and is genetically classified into mainland and island types. Here, we sequenced the whole chloroplast genome of mainlandA. spathulifoliusand compared it with those of the island type and otherAsterspecies. The chloroplast genome of mainlandA. spathulifoliusis 152,732 bp with a conserved quadripartite structure, has 37.28% guanine-cytosine (GC) content, and contains 114 non-redundant genes. Comparison of the chloroplast genomes between the twoA. spathulifoliuslines and the otherAsterspecies revealed that their sequences, GC contents, gene contents and orders, and exon-intron structure were well conserved; however, differences were observed in their lengths, repeat sequences, and the contraction and expansion of the inverted repeats. The variations were mostly in the single-copy regions and non-coding regions, which, together with the detected simple sequence repeats, could be used for the development of molecular markers to distinguish between these plants. AllAsterspecies clustered into a monophyletic group, but the chloroplast genome of mainlandA. spathulifoliuswas more similar to the otherAsterspecies than to that of the islandA. spathulifolius. TheaccDandndhFgenes were detected to be under positive selection within theAsterlineage compared to other related taxa. The complete chloroplast genome of mainlandA. spathulifoliuspresented in this study will be helpful for species identification and the analysis of the genetic diversity, evolution, and phylogenetic relationships in theAstergenus and the Asteraceae.