Complete plastome sequence of Mallotus peltatus (Geiseler) Müll. Arg. (Euphorbiaceae): A beverage and medicinal plant in Hainan, China

The complete plastome of Acalypha australis (Euphorbiaceae) and its phylogenetic analysis

Acalypha australis L. 1753 is a potherb popular among Asian populations and is a traditional herbal medicine. In the current study, the overall genetic diversity of A. australis still needs to be better. Here, we assembled and characterized the complete plastome of A. australis. The plastome is 168,885 bp in length with a large single-copy (LSC) of 94,576 bp, a small single-copy (SSC) of 19,715 bp, and two copies of inverted repeat region (IRs) of 27,297 bp each. The overall GC content is 34.9%. The plastome contains 127 genes, including 83 protein-coding genes, 36 tRNA genes, and eight rRNA genes. Phylogenomic analysis of the representative species of Euphorbiaceae showed that A. australis and A. hispida formed a monophyletic sister clade. The results of this study will support further research on the evolution and conservation of the Euphorbiaceae species; they will benefit pharmaceutical applications and ornamentation of the medicinal plant A. australis.

The complete chloroplast genome and phylogenetic analysis of Acalypha hispida Burm. f. (Euphorbiaceae), an ornamental and medicinal plant

Acalypha hispida Burm. f. (1768) is an evergreen shrub native to New Guinea and the Bismarck Archipelago. Currently, it is widely cultivated as an ornamental and medicinal plant in tropical and subtropical areas worldwide. This study characterized the complete chloroplast genome of A. hispida, which is 172,122 bp in length and consists of large single-copy (LSC) and small single-copy (SSC) regions of 97,025 bp and 19,787 bp, respectively, that are separated by a pair of 27,655 bp inverted repeat (IR) regions. The overall GC content of the genome is 34.22%. The genome contains 131 genes, including 86 protein-coding, 37 tRNA, and eight rRNA genes. Phylogenetic analysis indicates that A. hispida is closely related to Ricinus communis and Cleidiocarpon cavaleriei in the Euphorbiaceae family. The complete chloroplast genome of A. hispida provides genomic resources and potential markers suitable for future species identification and speciation studies of the genus Acalypheae and will also provide important information on the phylogenetic relationships of the Euphorbiaceae family.

The evolutionary fate of rpl32 and rps16 losses in the Euphorbia schimperi (Euphorbiaceae) plastome

Gene transfers from mitochondria and plastids to the nucleus are an important process in the evolution of the eukaryotic cell. Plastid (pt) gene losses have been documented in multiple angiosperm lineages and are often associated with functional transfers to the nucleus or substitutions by duplicated nuclear genes targeted to both the plastid and mitochondrion. The plastid genome sequence of Euphorbia schimperi was assembled and three major genomic changes were detected, the complete loss of rpl32 and pseudogenization of rps16 and infA. The nuclear transcriptome of E. schimperi was sequenced to investigate the transfer/substitution of the rpl32 and rps16 genes to the nucleus. Transfer of plastid-encoded rpl32 to the nucleus was identified previously in three families of Malpighiales, Rhizophoraceae, Salicaceae and Passifloraceae. An E. schimperi transcript of pt SOD-1-RPL32 confirmed that the transfer in Euphorbiaceae is similar to other Malpighiales indicating that it occurred early in the divergence of the order. Ribosomal protein S16 (rps16) is encoded in the plastome in most angiosperms but not in Salicaceae and Passifloraceae. Substitution of the E. schimperi pt rps16 was likely due to a duplication of nuclear-encoded mitochondrial-targeted rps16 resulting in copies dually targeted to the mitochondrion and plastid. Sequences of RPS16-1 and RPS16-2 in the three families of Malpighiales (Salicaceae, Passifloraceae and Euphorbiaceae) have high sequence identity suggesting that the substitution event dates to the early divergence within Malpighiales.