Comparative genomics in plant fungal pathogens (Mycosphaerellaceae): variation in mitochondrial composition due to at least five independent intron invasions

Abstract

AbstractFungi provide new opportunities to study highly differentiated mitochondrial DNA. Mycosphaerellaceae is a highly diverse fungal family containing a variety of pathogens affecting many economically important crops.Mitochondria plays a major role in fungal metabolism and fungicide resistance but up until now only two annotated mitochondrial genomes have been published in this family. We sequenced and annotated mitochondrial genomes of selected Mycosphaerellaceae species that diverged ∼66 MYA. During this time frame, mitochondrial genomes expanded significantly due to at least five independent invasions of introns into different electron transport chain genes. Comparative analysis revealed high variability in size and gene order among mitochondrial genomes even of closely related organisms, truncated extra gene copies and, accessory genes in some species. Gene order variability was common probably due to rearrangements caused by mobile intron invasion. Three threecox1copies and bicistronic transcription ofnad2-nad3andatp6-atp8inPseudocercospora fijiensiswere confirmed experimentally. Even though we found variation in mitochondrial genome composition, there was no evidence of hybridization when comparing nuclear and mitochondrial dataset sets for fungal plant pathogens analyzed here. Disentangling the causes of variation in mitochondrial genome composition in plant pathogenic fungal move us closer to understanding the molecular mechanisms responsible for vital functions in fungi ultimately aiding in controlling these diseases.