Complete Chloroplast Genomes and Phylogenetic Relationships of and (Nyctaginaceae).

L. (Nyctaginaceae) is a South American native woody flowering shrub of high ornamental, economic, and medicinal value which is susceptible to cold damage. We sequenced the complete chloroplast (cp) genome of and , two morphologically similar species differing in cold resistance. Both genomes showed a typical quadripartite structure consisting of one large single-copy region, one small single-copy region, and two inverted repeat regions. The cp genome size of and was 154,520 and 154,542 bp, respectively, with 131 genes, including 86 protein-coding, 37 transfer RNA, and 8 ribosomal RNA genes. In addition, the genomes contained 270 and 271 simple sequence repeats, respectively, with mononucleotide repeats being the most abundant. Eight highly variable sites (, , , , , , , and ) with high nucleotide diversity were identified as potential molecular markers. Phylogenetic analysis revealed a close relationship between and . These findings not only contribute to understanding the mechanism by which the cp genome responds to low-temperature stress in and elucidating the evolutionary characteristics and phylogenetic relationships among species, but also provide important evidence for the accurate identification and breeding of superior cold-tolerant cultivars.