Multichromosomal Mitochondrial Genome of Punica granatum: Comparative Evolutionary Analysis and Gene Transformation from chloroplast genomes

Background: Punica granatum is an essentially important fruit tree that has important economic, medicinal and ornamental properties. At present, there are few reports on the mitochondrial genome of pomegranate. To further understand the organization, variation, and evolution of pomegranate mitogenomes, the P. granatum mitogenome was sequenced and assembled in the study. Results The genome structure was multi-chromosomes with seven circular chromosomes, measuring 382,774 bp in length with a 45.91% GC content. It contained 74 genes, including 46 protein-coding genes, 25 tRNA genes, and three rRNA genes. There were 188 pairs of dispersed repeats with lengths greater than or equal to 30, which were mainly reverse complementary repeats. The mitogenome analysis identified 114SSRs and 466 RNA editing sites. Analyses of codon usage, nucleotide diversity and gene migration from chloroplast to mitochondrial were also conducted. The collinear and comparative analysis of mitochondrial structures between P. granatum and its proximal species indicated that P. granatum was closely related to Lagerstroemia indica. Phylogenetic examination based on the mitogenome also confirmed the evolutionary relationship. Conclusion The results provided the predominant information for pomegranate evolutionary biology and to promote the species germplasm utilization.