W331 Wheat Leaf Rust, Puccinia triticina, Genome Sequencing and the Differences Amongst Races

Date: Monday, January 16, 2012
Time: 2:30 PM
Room: Sunset
John Fellers , USDA-ARS, Manhattan, KS
Christina Cuomo , Broad Institute of MIT & Harvard, Cambridge, MA
Guus Bakkeren , Agriculture & Agri-Food Canada, Summerland, BC, Canada
Les J. Szabo , USDA-ARS-Cereal Disease Lab, St. Paul, MN
Puccinia triticina Eriks is the causal agent of leaf (brown) rust in wheat and instigates significant economic losses each year.  In most wheat producing areas, the fungus reproduces asexually by producing urediniospores that are spread by the wind.  Leaf rust is a difficult pathogen to work with in the lab because it needs the alternate host, Thalictrum spp, for sexual recombination and is an obligate biotroph.  We set out to sequence the genome of P. triticina as an effort to understand biotrophic nature, race evolution, and host interactions.  Race 1, BBBD was selected to sequence as it is the most avirulent race known.  The first assembly was released in February of 2010 and contained 38,787 contigs in 24,434 scaffolds for a total of 159.4 Mb.  Three other races, TNRJ, FBDS and SBDG  were sequenced using Solexa and SNPs were identified.  cDNA libraries of infected leaf tissue, haustoria, fresh spores and germinated spores were sequenced and used for gene predictions.  Just over 11,000 genes were identified by computer prediction, however, we believe it is under estimated.  A second round of 454 genome sequencing was performed over the Summer of 2011 and is currently being assembled.  Also, 56 different races are being sequenced this winter using Solexa.