Unraveling the complex evolutionary features of the Cinnamomum camphora mitochondrial genome.

Abstract

Key message: We reported the mitochondrial genome of Cinnamomum camphora for the first time, revealing frequent rearrangement events in the non-coding regions of Magnoliids mitochondrial genomes. As one of the representative species in the Lauraceae family of Magnoliids, Cinnamomum camphora holds significant economic and ecological value. In this study, the mitochondrial genome (mitogenome) of C. camphora was complete assembled and annotated using PacBio HiFi sequencing. The C. camphora mitogenome is characterized by a branch structure, spans 900,894 bp, and contains 43 protein-coding genes (PCGs), 24 tRNAs, and 3 rRNAs. Most of these PCGs are under purifying selection, with only two (ccmFc and rps7) exhibiting signs of positive selection. The C. camphora mitogenome contains numerous repetitive sequences and intracellular gene transfers, with a total of 36 mitochondrial plastid DNAs, amounting to a combined length of 23,816 bp. Comparative analysis revealed that the non-coding regions of Magnoliids mitogenomes have undergone frequent rearrangements during evolution, but the coding sequences remain highly conserved (more than 98% similarity for protein-coding sequences). Furthermore, a maximum-likelihood phylogenetic tree was reconstructed based on 25 PCGs from 23 plant mitogenomes. The analysis supports the closest relationship between C. camphora and C. chekiangense, consistent with the APG IV classification system. This study elucidates the unique evolutionary features of the C. camphora mitogenome, which will provide valuable insights into the study of genetics and evolution of the family Lauraceae.