Title:
Explaining differential virulence in strains of Cronartium harknessii through comparative genomics
Abstract:
Cronartium harknessii (E. Meinecke), the fugal pathogen that causes western gall rust, has variable rates of susceptibility and infection among Pinus spp. Recently we used the population structure of C. harknessii and the host species lodgepole pine (Pinus contorta var. latifolia Engelm.), jack pine (Pinus banksiana Lamb) and their hybrids along with a factorial study of virulence of C. harknessii lineages to test the hypothesis that there is a coevolutionary relationship between host and pathogen. Our results show differential response to fungal lineages with resilience structure of jack pine > hybrids > lodgepole pine. Additionally, we found that there is correlation between C. harknessii lineage and host. Together these results support a coevolutionary relationship amongst host and pathogen. However, while our study found structure at microsatellite loci, there were numerous clones removed prior to population genetic analysis and ITS/IGS sequence differentiation between strains was too low to recover the structure. The lack of structure found in sequence data led to the question: What is different among the strains that is causing differential virulence in hosts? To test the hypothesis that there are structural variants rather than point mutations among strains that are causing differences in virulence we generated the first genomes for C. harknessii. We produced two near chromosome level assemblies and re-sequenced 54 additional pooled gall samples from each strain. The eastern and western reference assemblies have 18 and 17 scaffolds, respectively. Preliminary examination of the two reference genomes indicates that there are genomic differences that could account for variations in virulence similar to what is seen in the fusarium rust.
Bio:
Dr. Rhiannon Peery received an MSc in 2005 from Central Washington University and a PhD in 2015 from the University of Illinois followed by two postdocs and a research associate position at UAlberta. During her career Dr. Peery has worked on a wide variety of systems from conifers, to carrots, and chronic wasting disease and considers all her work as falling under the umbrella of applied computational biology and genomics. Her research focuses on the integration of methods from bioinformatics, population genomics, phylogenomics, and landscape ecology applied to questions about forest health. Currently Dr. Peery is the bioinformatician on the TRIA-FoR Genome Canada grant co-lead by Dr. Cullingham.