Fine mapping and characterization of Sr21, a temperature-sensitive diploid wheat resistance gene effective against the Puccinia graminis f. sp. tritici Ug99 race group

Shisheng Chen, Matthew N. Rouse, Wenjun Zhang, Yue Jin, Eduard Akhunov, Yuming Wei, Jorge Dubcovsky

Research output: Contribution to journalArticlepeer-review

24 Scopus citations

Abstract

Key message: The diploid wheat stem rust resistance geneSr21 confers temperature-sensitive resistance to isolates of the Ug99 group and maps to the middle of the long arm of chromosome 2Am.

Abstract: A race of Pucciniagraminis f. sp. tritici, the causal pathogen of stem rust of wheat, known as Ug99, and its variants, are virulent to plants carrying stem rust resistance genes currently deployed in most wheat cultivars worldwide. Therefore, identification, mapping and deployment of effective resistance genes are critical to reduce this threat. Resistance gene Sr21 identified in diploid wheat T. monococcum can be effective against races from the Ug99 race group, but both susceptible and partial resistant reactions have been reported in previous studies. To clarify this conflicting information we screened four monogenic lines with Sr21 and four susceptible controls with 16 Pgt isolates including five isolates of the Ug99 race group under three different temperatures and three different photoperiods. We observed that, temperature influences the interaction between monogenic lines with Sr21 and Ug99 race group isolates, and may be one source of previous inconsistencies. This result indicates that, although Sr21 confers partial resistance against Ug99, its effectiveness can be modulated by environmental conditions and should not be deployed alone. Using two large diploid wheat-mapping populations (total 3,788 F2 plants) we mapped Sr21 approximately 50 cM from the centromere on the long arm of chromosome 2Am within a 0.20 cM interval flanked by sequence-based markers FD527726 and EX594406. The closely linked markers identified in this study will be useful to reduce the T. monococcum segments introgressed into common wheat, accelerate Sr21 deployment in wheat breeding programs, and facilitate the map-based cloning of this gene.

Original languageEnglish (US)
Pages (from-to)645-656
Number of pages12
JournalTheoretical and Applied Genetics
Volume128
Issue number4
DOIs
StatePublished - Apr 2015

Bibliographical note

Funding Information:
This project was supported by the Borlaug Global Rust Initiative, by the National Research Initiative Competitive Grants 2011-68002-30029 (Triticeae-CAP) and 2012-67013-19401 from the United States Department of Agriculture (USDA) National Institute of Food and Agriculture (NIFA), USDA-Agricultural Research Service appropriated project 3640-21220-021-00, USDA National Plant Disease Recovery System, and by support from the Howard Hughes Medical Institute and the Gordon and Betty Moore Foundation. We thank Mariana Padilla for excellent technical support.

Publisher Copyright:
© 2015, Springer-Verlag Berlin Heidelberg.

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