The Mitochondrial Genome of the Phytopathogenic Fungus Bipolaris sorokiniana and the Utility of Mitochondrial Genome to Infer Phylogeny of Dothideomycetes

Abstract

A number of species in <i>Bipolaris</i> are important plant pathogens. Due to a limited number of synapomorphic characters, it is difficult to perform species identification and to estimate phylogeny of <i>Bipolaris</i> based solely on morphology. In this study, we sequenced the complete mitochondrial genome of <i>Bipolaris sorokiniana</i>, and presented the detailed annotation of the genome. The <i>B. sorokiniana</i> mitochondrial genome is 137,775 bp long, and contains two ribosomal RNA genes, 12 core protein-coding genes, 38 tRNA genes. In addition, two ribosomal protein genes (<i>rps3</i> gene and <i>rps5</i> gene) and the fungal mitochondrial RNase P gene (<i>rnpB</i>) are identified. The large genome size is mostly determined by the presence of numerous intronic and intergenic regions. A total of 28 introns are inserted in eight core protein-coding genes. Together with the published mitochondrial genome sequences, we conducted a preliminary phylogenetic inference of Dothideomycetes under various datasets and substitution models. The monophyly of <i>Capnodiales</i>, <i>Botryosphaeriales</i> and <i>Pleosporales</i> are consistently supported in all analyses. The <i>Venturiaceae</i> forms an independent lineage, with a distant phylogenetic relationship to <i>Pleosporales</i>. At the family level, the <i>Mycosphaerellaceae</i>, <i>Botryosphaeriaceae</i>. <i>Phaeosphaeriaceae</i>, and <i>Pleosporaceae</i> are recognized in the majority of trees.