Mapping QTL for resistance to new virulent races of wheat stripe rust from two Argentinean wheat varieties

Authors: COBO, NICOLAS - University Of California, Davis; PLFUGER, LAURA - National Institute Of Agricultural Technology(INTA); Chen, Xianming; DUBCOVSKY, JORGE - University Of California, Davis

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/26/2018
Publication Date: 9/13/2018
Citation: Cobo, N., Plfuger, L., Chen, X., Dubcovsky, J. 2018. Mapping QTL for resistance to new virulent races of wheat stripe rust from two Argentinean wheat varieties. Crop Science. 58(6):2470-2483. https://doi.org/10.2135/cropsci2018.04.0286.
DOI: https://doi.org/10.2135/cropsci2018.04.0286

Interpretive Summary: During the last two decades, more virulent and aggressive races of the wheat stripe rust pathogen had spread worldwide causing devastating epidemics and prompting the search for new sources of resistance. Here we mapped four stripe rust resistance quantitative trait loci (QTL) effective against stripe rust races present in California, USA between 2012 and 2017. Recombinant inbred lines (RIL) developed from the cross between the Argentinean varieties Klein Proteo and Klein Chajá. We generated a map including 2,698 SNP and 108 SSR markers. The RIL population showed transgressive segregation in all six growing seasons relative to the parental lines, which showed moderate resistance. Analyses by year detected QTL conferring adult-plant resistance on chromosomes 1BL, 2BS, 3D centromeric (from Klein Chajá), and 4DL (from Klein Proteo). QYr.ucw-1BL, mapped in the Yr29 resistance gene region, was significant in all seasons and explained 31-32.8 % of the observed variation. QYr.ucw-2BS showed a stronger effect than QYr.ucw-1BL but was effective only in some of the years. This QTL also conferred seedling resistance suggesting that it is an all-stage resistance gene. QYr.ucw-3D centromeric and QYr.ucw-4DL showed a smaller effect than the previous QTL and were significant only in some of the experiments. No significant interactions were detected among QTL. We compared these QTL to previously mapped stripe rust resistance genes and QTL to facilitate their utilization in wheat breeding programs.

Technical Abstract: During the last two decades, more virulent and aggressive races of Puccinia striiformis f. sp. tritici (Pst) had spread worldwide causing devastating epidemics and prompting the search for new sources of resistance. Here we mapped four stripe rust resistance QTL effective against the Pst races present in California, USA between 2012 and 2017. Recombinant inbred lines (RIL) developed from the cross between the Argentinean varieties Klein Proteo and Klein Chajá. We generated a map including 2,698 SNP and 108 SSR markers. The RIL population showed transgressive segregation in all six growing seasons relative to the parental lines, which showed moderate resistance. Analyses by year detected QTL conferring adult-plant resistance on chromosomes 1BL, 2BS, 3D centromeric (from Klein Chajá), and 4DL (from Klein Proteo). QYr.ucw-1BL, mapped in the Yr29 resistance gene region, was significant in all seasons (P < 0.01) and explained 31-32.8 % of the observed variation. QYr.ucw-2BS showed a stronger effect than QYr.ucw-1BL but was effective only in some of the years. This QTL also conferred seedling resistance suggesting that it is an all-stage resistance gene. QYr.ucw-3D centromeric and QYr.ucw-4DL showed a smaller effect than the previous QTL and were significant only in some of the experiments. No significant interactions were detected among QTL. We compared these QTL to previously mapped stripe rust resistance genes and QTL to facilitate their utilization in wheat breeding programs.