Complete mitochondrial genome of Persicaria maackiana reveals genome features, phylogenetic relationships, and nucleotide substitution rates

Persicaria maackiana, belonging to the Polygonaceae family, is widely distributed throughout Northeast Asia (the Russian Far East, China, Japan, and the Korean Peninsula). Despite extensive research conducted on the plastid genomes (plastomes) of various plant species, limited studies have focused on mitochondrial genomes (mitogenomes). In particular, few mitogenome research and few comparative studies of the Polygonaceae family are reported. In this study, we aimed to comparatively analyze the mitogenome characteristics of P. maackiana and other previously reported Polygonaceae mitogenomes, focusing on phylogenetic analysis and nucleotide substitution rate analysis. The mitogenome of P. maackiana was assembled using the Illumina and PacBio sequencing platforms, revealing a length of 401,682 bp and a circular structure. It contains 35 protein-coding genes (PCGs), 19 transfer RNAs (tRNAs), and three ribosomal RNAs (rRNAs). We identified 368 C-to-U RNA editing sites within the mitogenome of P. maackiana, with the nad4 gene exhibiting the highest number of RNA editing sites. Furthermore, 34 plastid fragments, including 11 complete tRNAs and petL genes, were detected in the mitogenome. Phylogenetic analysis based on 76 shared plastid PCGs and 14 shared mitochondrial PCGs revealed a single clade formed by P. maackiana and P. maculosa. The nucleotide substitution rate analysis of plastid and mitochondrial genes using the six Polygonaceae species revealed higher substitution rates in mitochondrial genes than those in plastid genes. This study provides valuable insights into the mitogenome of P. maackiana, which can potentially contribute to future evolutionary studies of the Polygonaceae family.