ARS | Publication request: Intraspecific comparison and annotation of two complete mitochondrial genome sequences from the plant pathogenic fungus Mycosphaerella graminicola

Submitted to: Fungal Genetics and Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 7, 2007
Publication Date: April 10, 2008
Repository URL: http://hdl.handle.net/10113/16139
Citation: Torriani, S.F., Goodwin, S.B., Kema, G.H., Pangilinan, J.L., Mcdonald, B.A. 2008. Intraspecific comparison and annotation of two complete mitochondrial genome sequences from the plant pathogenic fungus Mycosphaerella graminicola. Fungal Genetics and Biology. 45:628-637.

Interpretive Summary: Mitochondria provide the energy that fuels cellular metabolism. Because they are essential for cell functioning they can be targets of fungicides and other compounds in plant protection. However, relatively little is known about gene content of mitochondrial genomes or about the levels of genetic variation among mitochondria within species, particularly for plant pathogenic fungi. To rectify this situation, complete mitochondrial genomes were sequenced from two strains of the septoria tritici blotch pathogen of wheat, Mycosphaerella graminicola, and compared to assess the level and degree of polymorphism. The complete mitochondrial genome of M. graminicola is a circular molecule of 43,961 base pairs containing genes coding for 14 proteins related to energy production, one gene for making RNA, two ribosomal RNA genes and 27 transfer RNAs. Approximately one third of the genome was inverted relative to what was expected from other fungi, probably due to at least one major rearrangement. The transfer RNA genes were grouped in a way that might facilitate such rearrangements. Nucleotide variation was low between strains originating from Europe and North America, supporting previous findings. The two sequences provide the basis for developing new tools to identify polymorphic regions in the mitochondrial genome to better understand the conflicting pattern of high nuclear and low mitochondrial diversity present in M. graminicola populations around the world. This information will be useful to mycologists and population geneticists to understand the mating behavior and migration patterns of this fungus, to plant pathologists trying to identify potential new fungicide targets, and to evolutionary biologists to understand the past evolutionary history of this organism.

Technical Abstract: The complete mitochondrial genome of the plant pathogenic fungus Mycosphaerella graminicola is a circular molecule of 43,961 bp containing the typical genes coding for 14 proteins related to oxidative phosphorylation, one RNA polymerase, two rRNA genes and a set of 27 tRNAs. Most of the tRNA genes were grouped, with the two larger tRNA gene clusters showing conservation in gene position with other ascomycetes. Intraspecific nucleotide variation was low between two strains of M. graminicola (IPO323 and STBB1) originating from Europe and North America, supporting previous findings of low mitochondrial diversity revealed by RFLP analysis. The two sequences provide the basis for developing new tools to identify polymorphic regions in the mitochondrial genome to better understand the conflicting pattern of high nuclear and low mitochondrial diversity present in M. graminicola populations around the world.