Comparative Analysis of (Aeridinae, Orchidaceae) Plastomes Shed Light on Plastomes Evolution and Barcodes Investigation.

, a genus of the subtribe Aeridinae of Orchidaceae, comprises ca. 40 species. Members of exhibit unique morphological characteristics and represent a valuable ornamental orchid genus. However, due to the scarcity of distinct morphological characters, species identification within this genus is ambiguous and controversial. In the present study, next-generation sequencing (NGS) methods were used to assemble the plastomes of five species and compare them with one publicly available plastid genome data. The plastomes of possessed a quadripartite structure, with sizes ranging from 146,243 bp to 147,430 bp. The plastomes of six species contained a total of 120 genes, comprising 74 protein-coding genes, 38 tRNA genes and eight rRNA genes. Notably, all genes were pseudogenized or lost. An analysis of codon usage bias showed that leucine (Leu) exhibited the highest frequency, while cysteine (Cys) exhibited the lowest frequency. A total of 57 to 64 SSRs and 42 to 49 long repeats were identified. Five regions and five coding sequences were identified for DNA barcodes, based on the nucleotide diversity (Pi) analysis. The species of constituted a monophyletic group and were sister to with strong support. Our study deepens the understanding of species identification, plastome evolution and the phylogenetic positions of .