Long repeat sequences mediated multiple mitogenome conformations of mulberries (<i>Morus</i> spp.), an important economic plant in China

Abstract

Mulberries (genus <i>Morus</i>; Moraceae) hold significant economic value in sericulture and have great potential in the horticultural industry, food industry, and human health arenas worldwide. Since the advent of the genomic era, biological macromolecules of <i>Morus</i> species such as whole genome and plastome sequences have been reported, but mitochondrial genome sequences are relatively scarce which greatly hinders the comprehensive understanding of the evolutionary history and processes at work with <i>Morus</i>. Here, four <i>Morus</i> mitogenomes were assembled using Illumina and PacBio HiFi data. The results elucidated that the structure of the four mitogenomes was greatly heterogeneous due to the presence of different numbers of repeat-mediated recombination events with multiple conformations existing simultaneously in the mitogenome for each species. The genome size ranged from 359,062 to 376,846 bp. The repeat sequences and gene transfers from plastome to mitogenome varied widely among the four mitogenomes, which was the main cause of variation in mitogenome size. Finally, the evolutionary history of Rosales was inferred based on the mitogenome sequences. The analyses revealed a strong difference in the phylogenetic placement of Rhamnaceae compared to earlier plastid or nuclear phylogenies, likely due to the effects of ancient hybridizations. Overall, the results presented here will provide important genetic resources for the utilization of this important economic plant.

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