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United States Department of Agriculture

Agricultural Research Service

Research Project: GENETICS, POPULATION BIOLOGY, AND HOST-PARASITE INTERACTIONS OF CEREAL RUST FUNGI AND THEIR DISEASES

Location: Cereal Disease Laboratory

Title: Diagnostic and Co-Dominant PCR Markers for Stem Rust Resistance Genes Sr25 and Sr26

Authors
item Liu, S -
item Yu, L -
item Singh, R -
item Jin, Yue
item Anderson, A -

Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 9, 2009
Publication Date: October 31, 2009
Citation: Liu, S., Yu, L., Singh, R., Jin, Y., Anderson, A. 2009. Diagnostic and co-dominant PCR markers for stem rust resistance genes Sr25 and Sr26. Theoretical and Applied Genetics. 120:691-697.

Interpretive Summary: Wheat stem rust, caused by Puccinia graminis f. sp. tritici, is one of the most destructive diseases of wheat. A new stem rust race named TTKSK (syn. Ug99) and related races recently detected in Kenya are virulent to many designated and undesignated stem rust resistance genes. The emergence and spread of those races pose an imminent threat to wheat production worldwide. Genes Sr25 and Sr26 transferred into wheat from Thinopyrum ponticum are effective against these new stem rust races. DNA markers for Sr25 and Sr26 are needed to pyramid both genes into adapted germplasm. The objectives of this study were to develop DNA markers and test their utility in breeding. Co-dominant markers for Sr25 and Sr26 were identified. A diverse set of germplam consisting 170 lines from CIMMYT, China, USA and other counties were screened with these co-dominant markers for Sr25 and Sr26 to test the utility of these markers in breeding.

Technical Abstract: Wheat stem rust, caused by Puccinia graminis f. sp. tritici, is one of the most destructive diseases of wheat. A new stem rust race named TTKSK (syn. Ug99) and related races recently detected in Kenya are virulent to many designated and undesignated stem rust resistance genes. The emergence and spread of those races pose an imminent threat to wheat production worldwide. Genes Sr25 and Sr26 transferred into wheat from Thinopyrum (Th) ponticum (Podp.) Barkworth and Dewey are effective against these new stem rust races. DNA markers for Sr25 and Sr26 are needed to pyramid both genes into adapted germplasm. The objectives of this study were to 1) test previously available markers for genes Sr25 and Sr26; 2) develop and validate co-dominant markers for Sr25 and Sr26; and 3) screen wheat germplasm with co-dominant markers for Sr25 and Sr26. The previously published dominant markers Gb for Sr25 and Sr26#43 for Sr26 were validated with eight wheat lines with or without Sr25 or Sr26. We tested six published STS (sequence tagged site) markers amplifying diagnostic bands of Th. ponticum. Marker BF145935 consistently worked well and can be used as a co-dominant marker for Sr25. Among 16 STS markers developed from wheat ESTs mapped to deletion bin 6AL8-0.90-1.00, none of them was co-dominant in marking Sr26. However, five 6A-specific markers were identified. Multiplex PCR with marker Sr26#43 and 6A-specific marker BE518379 can be used as a co-dominant marker for Sr26. The co-dominant markers for Sr25 and Sr26 were validated with 37 lines with known stem rust resistance genes. A diverse set of germplam consisting 170 lines from CIMMYT, China, USA and other counties were screened with these co-dominant markers for Sr25 and Sr26. Five lines with the diagnostic fragment for gene Sr25 were identified, and they all have "Wheatear" in their pedigrees, which is known to carry Sr25. None of the 170 lines tested had Sr26, as expected.

Last Modified: 4/24/2014
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