# The Complete Mitochondrial Genome of the Dioscorea opposita Thunb. cv. Tiegun, a Traditional Medicinal and Edible Crop

## TL;DR

This paper presents the first complete mitochondrial genome of the medicinal and edible yam species Dioscorea opposita, revealing insights into its genetic structure and RNA editing patterns.

## Contribution

The study provides the first complete mitochondrial genome of D. opposita and identifies the highest number of C-to-U RNA editing sites in the nad4 gene among crop species.

## Key findings

- The mitochondrial genome of D. opposita is 493,268 bp with 45.67% GC content and includes 39 protein-coding genes.
- The nad4 gene has 60 C-to-U RNA editing sites, the highest count reported in any crop species.
- Structural variations and repeat sequences suggest roles in mitochondrial architecture and cytonuclear co-adaptation.

## Abstract

This study reports the first complete mitochondrial genome of Dioscorea opposita, which is one of the medicinal and edible homologous crops and is rich in various nutrients and functional compounds. The genome was assembled into four circular contigs totaling 493,268 bp, with a GC content of 45.67%. Interestingly, the 60 C-to-U editing sites in D. opposita nad4 constitute highest count so far documented for any crop species, implying a potentially pivotal role for this gene in energy metabolism and environmental adaptation. These findings provide valuable insights into the phylogenetic and gene function research of Dioscorea plants.

This study reports the first complete mitochondrial genome of the traditional medicinal and edible crop, D. opposita (493,268 bp, 45.67% GC). We annotated 39 unique protein-coding genes (PCGs), which included 24 core mitochondrial genes and 15 variable genes, as well as 19 tRNA genes and 3 rRNA genes, along with 245 SSRs and multiple repeat sequences. The longest palindromic repeat measured 260 bp, while the longest forward repeat was 24,068 bp. Furthermore, 723 RNA editing sites were discovered, all involving C-to-U edits, with the nad4 having the highest number of edits (60 sites in total). Comparative genomic and phylogenomic analyses revealed Tiegun yam conserved gene content but structural variations compared to other monocots, underscoring the role of repetitive sequences and recombination in shaping mitochondrial architecture and facilitating cytonuclear co-adaptation. These findings establish a crucial genomic foundation for understanding mitochondrial regulation of growth and metabolic traits in this important species, with implications for future molecular breeding and functional studies of medicinal compound biosynthesis.