Assembly and comparative analysis of the complete mitochondrial genome of Pinellia ternata.

Pinellia ternata is an important natural medicinal herb in China. However, it is susceptible to withering when exposed to high temperatures during growth, which limits its tuber production. Mitochondria usually function in stress response. The P. ternata mitochondrial (mt) genome has yet to be explored. Therefore, we integrated PacBio and Illumina sequencing reads to assemble and annotate the mt genome of P. ternata. The circular mt genome of P. ternata is 876 608bp in length and contains 38 protein-coding genes (PCGs), 20 tRNA genes and three rRNA genes. Codon usage, sequence repeats, RNA editing and gene migration from chloroplast (cp) to mt were also examined. Phylogenetic analysis based on the mt genomes of P. ternata and 36 other taxa revealed the taxonomic and evolutionary status of P. ternata. Furthermore, we investigated the mt genome size and GC content by comparing P. ternata with the other 35 species. An evaluation of non-synonymous substitutions and synonymous substitutions indicated that most PCGs in the mt genome underwent negative selection. Our results provide comprehensive information on the P. ternata mt genome, which may facilitate future research on the high-temperature response of P. ternata and provide new molecular insights on the Araceae family.