The mitochondrial genome of the arbuscular mycorrhizal fungus Gigaspora margarita reveals two unsuspected trans-splicing events of group I introns.
• Arbuscular mycorrhizal fungi (AMF) are ubiquitous organisms that benefit ecosystems through the establishment of an association with the roots of most plants: the mycorrhizal symbiosis. Despite their ecological importance, however, these fungi have been poorly studied at the genome level. • In this study, total DNA from the AMF Gigaspora margarita was subjected to a combination of 454 and Illumina sequencing, and the resulting reads were used to assemble its mitochondrial genome de novo. This genome was annotated and compared with those of other relatives to better comprehend the evolution of the AMF lineage. • The mitochondrial genome of G. margarita is unique in many ways, exhibiting a large size (97 kbp) and elevated GC content (45%). This genome also harbors molecular events that were previously unknown to occur in fungal mitochondrial genomes, including trans-splicing of group I introns from two different genes coding for the first subunit of the cytochrome oxidase and for the small subunit of the rRNA. • This study reports the second published genome from an AMF organelle, resulting in relevant DNA sequence information from this poorly studied fungal group, and providing new insights into the frequency, origin and evolution of trans-spliced group I introns found across the mitochondrial genomes of distantly related organisms.
Department of Biology, University of Ottawa, Ottawa, K1N 6N5, ON, Canada.
Adrian
A
Pelin
Department of Botany, University of British Columbia; Vancouver, V6T 1Z4, BC, Canada.
Jean-François
JF
Pombert
Dipartimento di Biologia Vegetale, Università di Torino, Torino, I-10125, Italy.
Alessandra
A
Salvioli
Department of Biology, University of Ottawa, Ottawa, K1N 6N5, ON, Canada.
Linda
L
Bonen
Dipartimento di Biologia Vegetale, Università di Torino, Torino, I-10125, Italy.
Paola
P
Bonfante
Department of Biology, University of Ottawa, Ottawa, K1N 6N5, ON, Canada.
Nicolas
N
Corradi
D001483:Base Sequence; D018651:Cichorium intybus / Q000382:microbiology*; D004271:DNA, Fungal / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D003576:Electron Transport Complex IV / Q000235:genetics; D016681:Genome, Fungal / Q000235:genetics; D054629:Genome, Mitochondrial / Q000235:genetics*; D055137:Glomeromycota / Q000235:genetics*; D059014:High-Throughput Nucleotide Sequencing; D007438:Introns / Q000235:genetics*; D008969:Molecular Sequence Data; D038821:Mycorrhizae / Q000235:genetics*; D010802:Phylogeny; D018517:Plant Roots / Q000382:microbiology; D012335:RNA, Ribosomal / Q000235:genetics; D017422:Sequence Analysis, DNA; D013559:Symbiosis; D020040:Trans-Splicing / Q000235:genetics
D004271:DNA, Fungal; D004275:DNA, Ribosomal; D012335:RNA, Ribosomal; D003576:Electron Transport Complex IV