Distinguish Dianthus species or varieties based on chloroplast genomes

Most plants belonging to the widely distributed genus Dianthus are used for gardening. Interspecific hybridization of different Dianthus species leads to blurred genetic backgrounds. To obtain more genomic resources and understand the phylogenetic relationships among Dianthus species, the chloroplast genomes of 12 Dianthus species, including nine Dianthus gratianopolitanus varieties, were analyzed. The chloroplast genomes of these 12 species exhibited similar sizes (149,474–149,735 bp), with Dianthus caryophyllus having a chloroplast genome size of 149,604 bp marked by a significant contraction in inverted repeats. In the chloroplast genome of Dianthus, we identified 124–126 annotated genes, including 83–84 protein-coding genes. Notably, D. caryophyllus had 83 protein-coding genes but lacked rpl2. The repeat sequences of the chloroplast genome were consistent among species, and variations in the sequence were limited and not prominent. However, notable gene replacements were observed in the boundary region. Phylogenetic analysis of Dianthus indicated that D. caryophyllus and D. gratianopolitanus were most closely related, suggesting that the degree of variation within nine Dianthus varieties was no less than the variation observed between species. These differences provide a theoretical foundation for a more comprehensive understanding of the diversity within Dianthus species.