Physiologic specialization of Puccinia triticina, the causal agent of wheat leaf rust, in Canada in 2010

Citation

McCallum, B.D., Seto-Goh, P., Xue, A. (2016). Physiologic specialization of Puccinia triticina, the causal agent of wheat leaf rust, in Canada in 2010, 38(4), 440-447. http://dx.doi.org/10.1080/07060661.2016.1261047

Plain language summary

The rust fungus that causes wheat leaf rust, Puccinia triticina, was collected across Canada in 2010. From these collections 399 genetically pure isolates were recovered. These were tested for virulence on a series of single gene differential wheat lines. From this analysis the virulence spectrum or race for each isolate was determined and the common races across regions in Canada were found. These results were compared to previous years results to determine whether virulence on each of the resistance genes tested was increasing or decreasing within the pathogen population. From this we can tell which resistance genes are still effective and which are not effective any more. This study represents the continuation of annual virulence survey information for this pathogen going back to the 1930s in efforts to understand and control this pathogen.

Abstract

© 2016 Her Majesty the Queen in Right of Canada, as represented by Agriculture and Agri-Food Canada (AAFC). Puccinia triticina Eriks., the causal agent of wheat leaf rust, was collected across Canada in 2010 to determine the virulence spectrum present in the pathogen population. From 314 infected leaf collections, 399 single pustule isolates were recovered, including 341 from Manitoba and Saskatchewan, 38 from Ontario, nine from Quebec and 11 from Prince Edward Island (PEI). When analysed for virulence on 16 standard differential lines, 41 different virulence phenotypes were identified. The most common were MLDS (26.1%), TDBJ (22.8%) and TDBG (11.8%). In Manitoba and Saskatchewan, the most common phenotypes were MLDS (29.6%), TDBJ (25.5%) and TDBG (13.8%), which were also abundant in 2009. In Ontario, the most common were MBTN (23.7%), TDBJ (10.5%), MCGJ, MCTN and MLDS (each at 7.9%), whereas in Quebec, each of the nine isolates analysed had a different phenotype. In PEI, the more commonly isolated phenotypes were MBNQ (six isolates), MBTN and MHNQ (two isolates each). Each population had unique virulence phenotypes, and the eastern populations were more diverse than the Manitoba and Saskatchewan population. Virulence trends from previous years continued in 2010, with increasing levels of virulence found for Lr9 and Lr17 while decreasing virulence was found for Lr2a, Lr14a and Lr24. There was no virulence found in 2010 for Lr19, Lr21, Lr22a, Lr29, Lr32 or Lr52.