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- Title
Mapping and characterization of wheat stem rust resistance genes <italic>SrTm5</italic> and <italic>Sr60</italic> from <italic>Triticum monococcum</italic>.
- Authors
Chen, Shisheng; Guo, Yan; Briggs, Jordan; Dubach, Felix; Chao, Shiaoman; Zhang, Wenjun; Rouse, Matthew N.; Dubcovsky, Jorge
- Abstract
Key message: The new stem rust resistance gene <italic>Sr60</italic> was fine-mapped to the distal region of chromosome arm 5AmS, and the TTKSK-effective gene <italic>SrTm5</italic> could be a new allele of <italic>Sr22.</italic>Abstract: The emergence and spread of new virulent races of the wheat stem rust pathogen (<italic>Puccinia graminis</italic> f. sp. <italic>tritici</italic>; <italic>Pgt</italic>), including the Ug99 race group, is a serious threat to global wheat production. In this study, we mapped and characterized two stem rust resistance genes from diploid wheat <italic>Triticum monococcum</italic> accession PI 306540. We mapped <italic>SrTm5</italic>, a previously postulated gene effective to Ug99, on chromosome arm 7AmL, completely linked to <italic>Sr22</italic>. <italic>SrTm5</italic> displayed a different race specificity compared to <italic>Sr22</italic> indicating that they are distinct. Sequencing of the <italic>Sr22</italic> homolog in PI 306540 revealed a novel haplotype. Characterization of the segregating populations with <italic>Pgt</italic> race QFCSC revealed an additional resistance gene on chromosome arm 5AmS that was assigned the official name <italic>Sr60</italic>. This gene was also effective against races QTHJC and SCCSC but not against TTKSK (a Ug99 group race). Using two large mapping populations (4046 gametes), we mapped <italic>Sr60</italic> within a 0.44 cM interval flanked by sequenced-based markers <italic>GH724575</italic> and <italic>CJ942731</italic>. These two markers delimit a 54.6-kb region in <italic>Brachypodium distachyon</italic> chromosome 4 and a 430-kb region in the Chinese Spring reference genome. Both regions include a leucine-rich repeat protein kinase (LRRK123.1) that represents a potential candidate gene. Three CC–NBS–LRR genes were found in the colinear <italic>Brachypodium</italic> region but not in the wheat genome. We are currently developing a Bacterial Artificial Chromosome library of PI 306540 to determine which of these candidate genes are present in the <italic>T. monococcum</italic> genome and to complete the cloning of <italic>Sr60</italic>.
- Subjects
WHEAT stem rusts; WHEAT disease &; pest resistance; PUCCINIA graminis; BRACHYPODIUM; LEUCINE
- Publication
Theoretical & Applied Genetics, 2018, Vol 131, Issue 3, p625
- ISSN
0040-5752
- Publication type
Article
- DOI
10.1007/s00122-017-3024-z