The assembled Banana dihaploid mitochondrial genome is compact with a high number of gene copies

Abstract

Banana being a major food crop all around the world, attracts various research interests in crop improvement. In banana, complete genome sequences of Musa accuminata and Musa balbisiana are available. However, the mitochondrial genome is not sequenced or assembled. Mitochondrial (mt) genes play an important role in flower and seed development and in Cytoplasmic Male Sterility. Unraveling banana mt genome architecture will be a foundation for understanding inheritance of traits and their evolution. In this study, the complete banana mt genome is assembled from the whole genome sequence data of the Musa acuminata subsp. malaccensis DH-Pahang. The mt genome sequence acquired by this approach was 409574 bp and it contains, 54 genes coding for 25 respiratory complex proteins 15 ribosomal proteins, 12 tRNA genes and two ribosomal RNA gene. Except atpB, rps11 and rps19 other genes are in multiple copies. The copy number is 12 in tRNA genes. In addition, nearly 25% tandem repeats are also present in it. These mt proteins are identical to the mt proteins present in the other members of AA genome and share 98% sequence similarity with M. balbisiana. The C to U RNA editing is profoundly higher (87 vs 13%) in transcripts of M. balbisiana (BB) compared to M. accuminata (AA). The banana AA mitochondrial genome is tightly packed with 233 genes, with less rearrangements and just 5.3% chloroplast DNA in it. The maintenance of high copy number of functional mt genes suggest that they have a crucial role in the evolution of banana.