Abstract

Pyrenophora semeniperda (anamorph Drechslera campulata) is a necrotrophic fungal seed pathogen of a variety of grass genra and species, including Bromus tectorum, an exotic grass that has invaded many natural ecosystems of the U.S. Intermountain West. As a natural seed pathogen of B. tectorum, P. semeniperda has potential as a biocontrol agent due to its effectiveness at killing dormant B. tectorum seeds; however, few genetic resources exist for this fungus. Here, the genome assembly of a P. semeniperda isolate using 454 GS-FLX genomic and paired-end pyrosequencing techniques is presented. The total assembly is 32.5 Mb and contains 11,453 gene models greater than 24 amino acids. The assembly contains a variety of predicted genes that are involved in pathogenic pathways typically found in necrotrophic fungi. In addition, 454 sequence reads were used to identify single nucleotide polymorphisms between two isolates of P. semeniperda. In total, 20 SNP markers were developed for the purposes of recombination assesment of 600 individual P. semeniperda isolates representing 36 populations from throughout the U.S. Intermountain West. Although 17 of the fungal populations were fixed at all SNP loci, linkage disequilibrium was determined in the remaining 18 populations. This research demonstrates the effectiveness of the 454 GS-FLX sequencing technology, for de novo assembly and marker development of filamentous fungal genomes. Many features of the assembly match those of other Pyrenophora genomes including P. tritici-repentis and P. teres f. teres, which lend validity to our assembly. These findings present a significant resource for examining and furthering our understanding of P. semeniperda biology.

Degree

College and Department

Life Sciences; Plant and Wildlife Sciences

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