Submission Type
Oral Presentation
Abstract
The hetereothallic ascomycete Magnaporthe contains strains capable of infecting > 50 grass species. Despite the predominance of an asexual lifestyle the genomes of ten examined strains exhibit high levels of chromosomal structural diversity. Starships, a novel class of DNA transposons, have been identified in Magnaporthe and are likely involved in fungal genome evolution. Starships capture and relocate fungal genes throughout their host genomes and could function as recombinogenic substrates. These mobile genetic elements are inserted within the fungal chromosomal 5SrRNA genes resulting in gene disruption into two fragments, from positions 1-69 and 56-116. The software programs blastn, FACET, the Integrated Genome Viewer, ClustalX, and Mauve Alignment were the bioinformatic tools used to determine the locations, lengths, structural patterns, and gene contents of Starships. There is a consistent transversion mutation of a cytosine (pyrimidine) to an adenine (purine) at the 65th position of the 1-69 5SrRNA segments; 56-116 5SrRNA segments retain the duplicate cytosine. Both intact (full length) and truncated (partial) Starships were detected. Intact Starships (ranging in length from 10 kb - 250 kb) were identified by the retention of conserved border sequences. Using border sequence motifs (e.g. inverted repeats, novel linker sequences) we identified five categories of Starships. The chromosomal locations and gene contents of Starships were highly variable with few instances of transposon synteny. The Starships could serve as a mechanism to overcome the long-term consequences of Mueller’s ratchet by facilitating intragenomic recombination events among both fungal chromosomal loci and other Starship elements containing homologous sequences.
Included in
Role of giant transposons (Starships) in facilitating fungal genome evolution
The hetereothallic ascomycete Magnaporthe contains strains capable of infecting > 50 grass species. Despite the predominance of an asexual lifestyle the genomes of ten examined strains exhibit high levels of chromosomal structural diversity. Starships, a novel class of DNA transposons, have been identified in Magnaporthe and are likely involved in fungal genome evolution. Starships capture and relocate fungal genes throughout their host genomes and could function as recombinogenic substrates. These mobile genetic elements are inserted within the fungal chromosomal 5SrRNA genes resulting in gene disruption into two fragments, from positions 1-69 and 56-116. The software programs blastn, FACET, the Integrated Genome Viewer, ClustalX, and Mauve Alignment were the bioinformatic tools used to determine the locations, lengths, structural patterns, and gene contents of Starships. There is a consistent transversion mutation of a cytosine (pyrimidine) to an adenine (purine) at the 65th position of the 1-69 5SrRNA segments; 56-116 5SrRNA segments retain the duplicate cytosine. Both intact (full length) and truncated (partial) Starships were detected. Intact Starships (ranging in length from 10 kb - 250 kb) were identified by the retention of conserved border sequences. Using border sequence motifs (e.g. inverted repeats, novel linker sequences) we identified five categories of Starships. The chromosomal locations and gene contents of Starships were highly variable with few instances of transposon synteny. The Starships could serve as a mechanism to overcome the long-term consequences of Mueller’s ratchet by facilitating intragenomic recombination events among both fungal chromosomal loci and other Starship elements containing homologous sequences.
Comments
Blake Park1, Mallory Bermudez1, Camden Ping1, Morgan Morrow1, Patrick Calie1, Mark Farman2
1Department of Biological Sciences, Eastern Kentucky University, Richmond, KY
2Department of Plant Pathology, University of Kentucky, Lexington, KY