Abstract: Eucalyptus urophylla × E. grandis is a major hybrid species of timber plantations. However, our understanding of Eucalyptus mitochondrial genome, especially within the Myrtaceae family, is limited. In this study, we employed hybrid sequencing combining the Illumina and Oxford Nanopore sequencing to assemble and annotate the mitogenome (mtDNA) of E. urophylla × E. grandis. Our results reveal a structure characterized by one circular molecule, with a cumulative length of 483,907 base pairs (bp) and a GC content of 44.96%. The circular molecule collectively harbored 59 annotated genes. Among these, 38 were unique protein-coding genes (PCGs), accompanied by 18 transfer RNA (tRNA) genes and 3 ribosomal RNA (rRNA) genes. Our study also examined repetitive sequences, RNA editing sites, and intracellular sequence transfers within the mtDNA. Furthermore, we conducted a phylogenetic analysis between E. urophylla × E. grandis and 30 closely related species based on genetic affinities. The outcomes furnish a high-quality organelle genome for E. urophylla × E. grandis, thereby explaining basic insights into organelle genome evolution and phylogenetic relationships.

Key words: Eucalyptus urophylla × E. grandis, Myrtaceae, Mitochondrial genome, Repetitive sequences, RNA editing, Phylogenetic relationship