Report on the complete mitochondrial genome of the critically endangered and endemic Lauraceae plant Syndiclis anlungensis in China

Background Syndiclis anlungensis is a critically endangered (CR) species belonging to the genus Syndiclis in the family Lauraceae. However, the complete mitochondrial genome of this species has not yet been systematically described, hindering our understanding of the genetic diversity and evolutionary relationships of mitochondrial genomes within the genus Syndiclis . Result This study combined Illumina and Oxford Nanopore sequencing technologies to complete the sequencing, assembly, and annotation of the mitochondrial genome of S. anlungensis . The mitochondrial genome of S. anlungensis has a total length of 2,370,899 bp, comprising 26 core protein-coding genes (PCGs), 18 variable PCGs, and 55 tRNA genes, exhibiting a multipartite substructure mediated by 3 direct repeats. Analysis revealed that the genome contains 703 simple sequence repeats (SSRs), 204 tandem repeats, and 1,993 pairs of dispersed repeats. Among the mitochondrial PCGs, 93.1% of high-frequency codons end with A/T. A total of 755 RNA editing sites were identified, with 357 sites (47.28%) resulting in amino acid residue changes from hydrophilic to hydrophobic and 69 sites (9.14%) showing hydrophobic-to-hydrophilic shifts. Ka/Ks analysis indicated that genes such as ccmFc and rpl16 are under positive selection. Additionally, 62 homologous fragments (totaling 67,900 bp) were identified between the mitochondrial and chloroplast genomes, accounting for approximately 2.8639% of the mitochondrial genome length. Phylogenetic analysis of the mitochondrial genome placed S. anlungensis at the basal position within Lauraceae, while chloroplast genome-based phylogeny revealed S. marlipoensis as the closest relative to S. anlungensis . Conclusions This study presents the first comprehensive decoding of the mitochondrial genome of S. anlungensis , unveiling its features of frequent recombination, repeat sequence expansion, and adaptive evolution. These findings provide critical data for understanding the evolutionary mechanisms of mitochondrial genomes in the genus Syndiclis , while establishing a molecular foundation for the conservation of its genetic resources and the development of population restoration strategies.