Abstract
Background/Objectives: Chionanthus retusus Lindl. & Paxton is an ornamental tree species native to North China. Research on the mitochondrial genome can elucidate the evolution and biological characteristics of C. retusus and better protect this important species. Methods and Results: This work aimed to clarify the evolutionary and phylogenetic links by sequencing, assembling, annotating, and analyzing the entire mitochondrial genome of C. retusus. The single-loop structure that made up the mitochondrial genome had a total length of 657,640 bp and a GC content of 44.52%. In total, 37 unique protein-coding genes, 20 tRNA genes, and 3 rRNA genes were identified. Numerous repeat sequences and migrating fragments of chloroplast sequences were found. Using the mitochondrial protein-coding genes to construct evolutionary trees, it was found that the closest relative of C. retusus is C. rupicola (Lingelsh.) Kiew. Conclusions: This research represents the first comprehensive set of data on the mitochondrial genome of an ancient (>500 yr) C. retusus specimen. In addition to elucidating the biological characteristics of C. retusus. The findings contribute to the Oleaceae mitochondrial genome database and offer valuable insights for future studies in molecular breeding, evolutionary biology, and genetic diversity conservation.