[Chloroplast genome structure characteristics and phylogenetic analysis of Artemisia indica]

Artemisia indica is an important medicinal plant in the Asteraceae family, but its molecular genetic information has been rarely reported. In this study, the chloroplast genome of A. indica was sequenced, assembled, and annotated by the high-throughput sequencing technology, and its sequence characteristics, repeat sequences, codon usage bias, and phylogeny were analyzed. The results showed that the length of the chloroplast genome for A. indica was 151 161 bp, which was a typical circular four-segment structure, including two inverted repeat regions(IRs), a large single-copy(LSC) region, and a small single-copy(SSC) region, with a GC content of 37.47%. A total of 132 genes were annotated, and 114 were obtained after de-duplication, including 80 protein-coding genes, 30 tRNA genes, and 4 rRNA genes. Fifty long repeat sequences and 191 SSRs were detected in the chloroplast genome of A. indica, and SSRs were mainly single nucleotides. Codon usage bias analysis showed that leucine was the most frequently used amino acid(10.77%) in the chloroplast genome, and there were 30 codons with relative synonymous codon usage(RSCU)>1 and all ended with A/U. The phylogenetic tree constructed based on the chloroplast genomes of the 19 species from the Asteraceae family showed that A. indica and A. argyi were closest in the genetic relationship, and Artemisia species clustered into separate evolutionary branches. The results of this study are expected to provide a theoretical basis for the genetic diversity and resource conservation of Artemisia medicinal plants.