Assembly, annotation, and comparative analysis of the first complete mitochondrial genome of Pennisetum sinese.

Pennisetum sinese, a perennial grass central to "Juncao Technology," holds considerable promise for non-grain biomass production and ecological restoration. Despite its agronomic value, the cytoplasmic genetic architecture of this species, particularly its mitochondrial genome, remains uncharacterized. Here, we present the first complete mitochondrial genome of the P. sinese assembled via hybrid long- and short-read sequencing. The genome adopts a multi-branched conformation spanning 405,186 bp with a GC content of 43.98%, and encodes 32 unique protein-coding genes, 20 tRNA genes, and three rRNA genes. We detected significant codon usage bias, abundant tandem repeats, and dispersed repeats. In addition, 24 chloroplast-derived homologous fragments totaling 13,053 bp were identified. Phylogenetic analysis confirms the placement of the P. sinese within the Poaceae clade, whereas synteny analysis reveals extensive structural rearrangements in its mitochondrial genome compared with closely related species. Furthermore, we predicted 454 C-to-U RNA editing sites. These findings establish a foundational genetic resource for P. sinese cytoplasmic inheritance and laying a foundation for future investigations into the molecular mechanisms underlying its high biomass yield and stress tolerance, informing future germplasm innovation.