Durable Leaf Rust Resistance in Wheat

1
Durable Leaf Rust Resistance in Wheat

• J. A. Kolmer
• USDA-ARS
• Cereal Disease Laboratory

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Puccinia triticina - Wheat Leaf Rust

• Most common rust of wheat in U.S.
• Occurs nearly wherever wheat is grown
• Asexual in
• North America
• 50-60 races in U.S.
• Annual yield losses

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Leaf Rust Virulence Dynamics Kansas - Nebraska
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U.S. Hard Red Spring Wheat

• Wheaton (1983) Lr10, Lr23, Lr13, Lr34 ?
• Norm (1992) Lr1, Lr10, Lr13, Lr16, Lr23, Lr34
• both highly resistance since release
• Alsen (2000) Lr2a, Lr10, Lr13, Lr23, Lr34
• R-MR
• Knudson (2002) Lr3, Lr10, Lr13, Lr16, Lr23, Lr34
• Briggs (2002) Lr13, Lr16, Lr30, Lr34
• Both highly resistant
• Marshall (1982) Lr2a, Lr10, Lr13, Lr34
• Mod. Susceptible

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Effective Lr genesin spring wheat cvs.
Alsen 2a,10, 13, 23, 34 5 -20 MR
Norm 1, 10, 16, 23, 13, 34 Trace R
Knudson 3, 10, 16, 23, 13, 34 Trace R
TcLr16 50 - 70 MS
TcLr23 5 - 10 R MR
TcLr34 5 - 10 M
Thatcher 50 - 80 S
Lr16, Lr23, Lr34 common in spring wheat
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South American Landraces

• Americano 25e (1918) Lr3, Lr16, LrX1,LrAPR
• Americano 44d (1918) 1-2 APR genes
• THBJ Field
• Tc2/Am. 25e LrAPR 2- 30 MRMS
• Tc2/Am.44d LrAPR 23 20 M
• Tc2/Am.44d LrAPR 2- 20 MRMS

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U.S. Soft Red Winter Wheat

• Coker 9663 (1996) Lr9, Lr10, Lr14a
• R-MR
• Pioneer 26R61 (1999) Lr13, Lr14b, Lr26
• R-MR

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Lr34 in U.S. Wheat

• Hard red spring wheat
• Minnesota
• common 1966-mid 1990s
• FHB resistant cvs. lack Lr34
• South Dakota -
• few cvs. with Lr34
• North Dakota -
• few cvs. with Lr34

TcLr34
Tc
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Lr34 in U.S. Wheat
TcLr34 Tc

• Soft red winter wheat - old and new cvs.
• - not present
• Hard red winter wheat - very rare
• Western spring wheat - not present

CSIRO PCR Marker
Tip die back
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Lr genes in U.S. Wheat

• Seedling resistance genes
• - lower ploidy relatives
• - common wheat
• Virulent races arise quickly
• Lr9, Lr16, Lr26 - still provide some
  resistance
• Adult Plant Genes
• Lr34 - not sufficient alone
• Lr12 - ineffective
• Lr13 - ineffective
• Lr23 - characteristics of APR
• Combinations of Lr34 effective seedling genes
• best resistance

TcLr34 TcLr13 TcLr12 Tc