Zhenzhen Dong,  Joshua M. Hegarty,  Junli Zhang,  Wenjun Zhang,  Xianming Chen,  Yonghong Zhou,  Jorge Dubcovsky

Theoretical and Applied Genetics; October 2017; vol.130; issue 10, pp 2127–2137

Abstract

Key message

This study validated one QTL for adult plant resistance to stripe rust, identified donor lines of the resistance allele, and demonstrated that it is different from previously namedYrgenes.

Abstract

The spread of more virulent and aggressive races of Puccinia striiformis f. sp. tritici (Pst, causal pathogen of stripe rust) after the year 2000 has caused substantial yield losses worldwide. To find new sources of resistance, we previously performed a genome-wide association study and identified a strong QTL for adult plant resistance on the short arm of chromosome 6B (QYr.ucw-6B). In this study, we validated QYr.ucw-6B in ten biparental populations, and mapped it 0.6 cM proximal to IWA7257 and 3.9 cM distal to IWA4408. We showed that QYr.ucw-6B is located approximately 15 cM proximal to the all-stage resistance gene Yr35 and that none of the resistant lines carries the previously cloned Yr36 gene. Based on these results, QYr.ucw-6B was assigned the name Yr78. This gene was not effective against Pst at the seedling stage, suggesting that it is an adult plant resistance gene. Yr78 has been effective against Pst races present in field experiments performed in the Western USA between 2011 and 2016. Since this gene is predicted to be present at low frequency in wheat germplasm from this region, it can provide a useful tool to diversify the sources of resistance against this devastating pathogen.

See: https://link.springer.com/article/10.1007/s00122-017-2946-9

Figure 1: Comparative maps of QYr.ucw-6B and Yr35.a Linkage map and QTL analysis based on F₂ plants from the population PI 519805 × Avocet ‘S’. b Linkage map of the population PI 494101 × Avocet ‘S’. The position of QYr.ucw-6B as a Mendelian gene in the two linkage maps is based on F₃ field data. c Map of Pst all-stage resistance gene Yr35 based on Dadkhodaie et al. (2011) including common marker gwm508. d Evaluation of the presence of Yr36 in the ten lines confirmed to carry QYr.ucw-6B. DIC = T. turgidum ssp. dicoccoides carrying the Yr36 gene (positive control)