Complete plastome sequences of H. paniculiflorum, H. stenophyllum and Homalium ceylanicum (Salicaceae): Three valuable forest tree species

Abstract Homalium (Salicaceae) is mainly distributed in tropical and subtropical regions. Here we report and characterize the complete plastid genome sequences of Homalium paniculiflorum, H. stenophyllum, and H. ceylanicum in an effort to provide genomic resources useful for promoting its systematics research. The plastomes of H. paniculiflorum, H. stenophyllum, and H. ceylanicum were found to possess a total length 157,206 bp, 156,395 bp, and 156,551 bp, respectively. They all have typical quadripartite structure of angiosperms, containing two Inverted Repeats (IRs) of 27,796 bp in H. paniculiflorum, 27,669 in H. stenophyllum and 27,639 bp in H. ceylanicum, a Large Single-Copy (LSC) region of 85,031 bp (H. paniculiflorum), 84,458 bp (H. stenophyllum) and 84,627 bp (H. ceylanicum), a Small Single-Copy (SSC) region of 16,584 bp (H. paniculiflorum), 16,599 bp (H. stenophyllum), and 16,646 bp (H. ceylanicum). The all plastome contains 111 genes, consisting of consisting of 77 unique protein-coding genes (seven of which are duplicated in the IR), 30 unique tRNA genes (seven of which are duplicated in the IR) and 4 unique rRNA genes. The overall A/T content in the plastomes of H. paniculiflorum, H. stenophyllum, and H. ceylanicum are 63.30, 63.20, and 63.20%. The complete plastome sequences of H. paniculiflorum, H. stenophyllum, and H. ceylanicum will provide a useful resource for the conservation genetics of the three species as well as for the phylogenetic studies of Homalium.