Characterization of the mitochondrial genome of Cucumis hystrix and comparison with other cucurbit crops

The mitochondria ofCucumis genus contain several intriguing features such as paternal inheritance and three-ring genome structure. However, the evolutionary relationships of mitochondria inCucumisremain elusive. Here, we assembled the mitochondrial genome ofC. hystrixand performed a comparative genomic analysis with other crops inthe Cucurbitaceae. The mitochondrial genome ofC. hystrixhas three circular-mapping chromosomes of lengths 1,113,461 bp, 110,683 bp, and 92,288 bp, which contain 73 genes including 38 protein-coding genes, 31tRNAgenes, and 4rRNAgenes. Repeat sequences, RNA editing, and horizontal gene transfer events were identified. The results of phylogenetic analyses, collinearity and gene clusters revealed thatC. hystrixis closer toC. sativus than to C. melo. Meanwhile, wedemonstrated mitochondrial paternal inheritance inC. hystrixbymolecular markers. In comparison with other cucurbitcrops, wefound amarker foridentification of germplasm resources ofCucumis. Collectively, our findings provide a tool to help clarify the paternal lineage within that genus in the evolution of Cucumis.