Complete Chloroplast Genome Sequence of <i>Dahlia imperialis</i> (Asteraceae): Comparative Analysis and Phylogenetic Relationships
2023
Shan-De Duan | Yang Liu | Li-Hong Hao | Di-Ying Xiang | Wen-Bin Yu | Juan Liang | Duan-Fen Chen | Shan-Ce Niu
The genus <i>Dahlia</i> has approximately 40 species; however, the complete chloroplast genome has been reported only for one species. Due to this lack of information on the chloroplast genomes, the phylogenetic relationships within the <i>Dahlia</i> genus remain unclear. Therefore, the present study sequenced the complete chloroplast genome of <i>D. imperialis</i> for the first time. This genome was 152,084 bp long with a typical quadripartite structure and a GC content of 38.45%. A total of 134 genes were annotated in the genome, including 86 protein-coding genes, 38 transfer RNA genes, 8 ribosomal RNA genes, and 2 pseudogenes. The detailed analysis identified UUA as the most frequently used codon and found 62 intergenic repeat sequences and 157 SSR loci in the <i>D. imperialis</i> genome. Phylogenetic analysis based on 49 chloroplast genomes showed that <i>Dahlia</i> was a monophyletic group, with <i>D. imperialis</i> positioned at the base of this clade. Network evolution and gene flow analysis unveiled extensive hybridization events within the Heliantheae alliance, especially in <i>Dahlia</i>. Thus, the comprehensive analysis of the complete chloroplast genome of <i>D. imperialis</i> enriches the information on the genetic resources of the Dahlia species, provides valuable information for reconstructing their phylogeny, and reveals the evolutionary dynamics of the <i>Dahlia</i> chloroplast genome.
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