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 ME 1 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?
• Why SNP? ü Ubiquitous — accessible, representative
• Why SNP? ü Ubiquitous — accessible, representative ü Variable mutation rates ü Suitable to automatic genotyping ü Amiable to sequence-based analytical tools ü Alternative approach
• Why SNP? • Development of SNP markers (poster: theme 1, #30 ) • Preliminary results
• Sampling 7
• Preliminary results 100 79 100 7 <50 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
• Preliminary results Aeg ETH durum 100 78 Durum 99 SA-5 NZ 100 SAF EU-7 CA-3 NA-4 ME-1 NA-1 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
• 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 2 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.