Analysis of the complete mitochondrial genome sequences of the soybean rust pathogens phakopsora pachyrhizi and p. meibomiae

Abstract

The mitochondrial (mt) genomes of two soybean rust pathogens, Phakopsora pachyrhizi and P. meibomiae, have been sequenced. The mt genome of P. pachyrhizi is a circular 31 825-bp molecule with a mean GC content of 34.6%, while P. meibomiae possesses a 32 520-bp circular molecule with a mean GC content of 34.9%. Both mt genomes contain the genes encoding ATP synthase subunits 6, 8 and 9 (atp6, atp8 and atp9), cytochrome oxidase subunits I, II and III (cox1, cox2 and cox3), apocytochrome b (cob), reduced nicotinamide adenine dinucleotide ubiquinone oxidoreductase subunits (nad1, nad2, nad3, nad4, nad4L, nad5 and nad6), the large and small mt ribosomal RNA genes, one ORF coding for a ribosomal protein (rps3), and a set of 24 tRNA genes that recognize codons for all amino acids. The order of the protein-coding genes and tRNA is identical in the two Phakopsora species, and all genes are transcribed from the same DNA strand clockwise. Introns were identified in the cox1, cob and mnl genes of both species, with three of the introns having ORFs with motifs similar to the LAGLIDADG endonucleases of other fungi. Phylogenetic analysis of the 14 shared protein-coding genes agrees with commonly accepted fungal taxonomy.