Assembly and Comparative Analysis of Aconitum soongaricum Mitochondrial Genome Provides Insights into Its Identification and Function

Aconitum soongaricum, a medicinal plant endemic to the Tianshan Mountains in Xinjiang, China, produces numerous natural compounds with potential medicinal value. Mitochondria function as energy hubs and play critical roles in plant development and stress adaptation; thus, their genomic composition underpins biological functions. Here, we assembled the complete mitochondrial genome of A. soongaricum using next- and third-generation sequencing data and performed comparative analyses with related species. The mitochondrial genome exhibited a typical circular structure of 487,849 bp with a GC content of 46.80%. A total of 77 genes were annotated, including 41 protein-coding genes (PCGs), three rRNAs, 31 tRNAs, and two pseudogenes. The genome showed a strong A/U bias at the third codon position and displayed C-to-U RNA editing transitions, whereas no U-to-C transitions were estimated. Maximum-likelihood phylogenetic analysis supported a close relationship among A. soongaricum, A. carmichaelii, and A. kusnezoffii, confirming the utility of mitochondrial genomes for genetic relationship inference in genus Aconitum. Divergence time estimation placed the differentiation of A. soongaricum from the other two species at approximately 4.19 million years ago (Mya). Additionally, we evaluated the expression levels of NADH dehydrogenase (nad) genes across different tissues and under drought stress using real-time PCR, revealing diverse expression patterns. Collectively, this study provides a foundation for future investigations into the genetic mechanisms underlying evolution, energy metabolism, and environmental adaptation in A. soongaricum.