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Origins of Host Specific Populations of Puccinia triticina Revealed by SNP Markers (Preliminary). M. Liu and J. A. Kolmer USDA-ARS Cereal Disease Laboratory, St. Paul, MN 55108. World-wide P. triticina SSR groups. North America South America Central Asia Middle East Europe New Zealand
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Origins of Host Specific Populations of Puccinia triticina Revealed by SNP Markers (Preliminary) M. Liu and J. A. Kolmer USDA-ARS Cereal Disease Laboratory, St. Paul, MN 55108
World-wide P. triticina SSR groups North America South America Central Asia Middle East Europe New Zealand South Africa Durum isolates (EU, SA, ME, NA) Aegilops speltoides 587 isolates FST = 0.331 Some geographical relationship SA, NA vs. EU, ME, CA, NZ, SAF Except ME1 with NA and SA Durum groups distinct from common wheat groups
Puccinia triticina host differentiation • Bread wheat type – highly variable for SSR genotype • Durum wheat type – relatively less variable for SSR genotype • Wild Emmer Wheat (AB) susceptible to bread wheat type – native to Fertile Crescent Is the common wheat type the original form of P. triticina – and durum type more recently derived?
Goal: To further infer the evolutionary relationships among populations with the aid of coalescence theory and DNA single nucleotide polymorphism (SNP) markers
Why SNP? • Development of SNP markers (poster: theme 1, #30 ) • Preliminary results
Why SNP? • Ubiquitous — accessible, representative
Why SNP? • Ubiquitous — accessible, representative • Variable mutation rates • Suitable to automatic genotyping • Amiable to sequence-based analytical tools • Alternative approach
Why SNP? • Development of SNP markers (poster: theme 1, #30 ) • Preliminary results
Sampling 7
Preliminary results Clusters of P. triticina populations based on 94 SNPs from three house keeping genes, seven SSR flanking regions and six IGV selected anonymous loci. L=134 CI=0.709 RI=0.884 100 79 100 <50 7
Preliminary results One of 258367 most parsimonious phylograms based on SNPs from three house keeping genes and six IGV selected anonymous loci. Isolates on durum wheat formed clade. L=271 CI=0.915 RI=0.955 Aeg ETH durum 100 78 Durum 99 SA-5 NZ SAF EU-7 100 CA-3 NA-4 ME-1 NA-1
Preliminary results Inference of haplotypes based on diploid (dikaryotic) data PHASE 2.1 Stephens, M et al 2001. A new statistical method for haplotype reconstruction from population data. American Journal of Human Genetics 68:978—989
Coalescence analysis Carbone Lab IM, IMa, IMa2 Department of Genome Science, U of Washington
ACKNOWLEDGEMENTS We thank Drs. Les Szabo, John Fellers and Christina Cuomo for facilitating ML to access IGV and Pt whole genome database; Kun Xiao, Jerry Johnson and Kim Phuong Nguyen for technical help.