Complete mitochondrial genome of Mentha spicata L.

<em>Mentha spicata</em> L. is the source of spearmint oil, which is used in many industries, including pharmaceuticals, chemicals, food, and cosmetics. However, the genetic relationship of<em> M. spicata</em> is fuzzy due to lacking genomics resources. Here, we assembled a complete mitochondrial genome (mitogenome) of<em> M. spicata</em> using Illumina and Oxford Nanopore sequencing data. This genome corresponded to three molecules: one linear molecule (M1) and two circular molecules (M2 and M3). It encoded 35 unique genes, including 26 protein-coding genes (PCGs), three ribosomal RNA (rRNA) genes, and six transfer RNA (tRNA) genes. In addition, we found that two pairs of repeats could mediate the link of the three independent molecules into one complete molecule. Repeat sequence analysis revealed a repeated characteristic of the initiation site of mitochondrial replication. This repeat is shared among the three molecules, showing a stem-loop structure. Subsequently, by comparing the mitogenome and chloroplast genome sequences, we identified 38 fragments transferred between the two organelles, where the exon 2 of <em>atp</em>F and the <em>atp</em>H gene derived from chloroplast remained intact in the mitogenome. We identified 202 RNA editing sites in protein-coding sequences based on RNA-seq data. We successfully validated 33 predicted RNA editing sites using PCR amplification and Sanger sequencing. This project reported the first mitogenome of<em> M. spicata, </em>which provides valuable information for variety breeding and germplasm identification and development of genetic resources of<em> M. spicata.</em>