1. Durable Leaf Rust Resistance in Wheat J. A. Kolmer USDA-ARS Cereal Disease Laboratory

2. 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

3. Leaf Rust Virulence Dynamics Kansas - Nebraska

4. U.S. Hard Red Spring Wheat  Wheaton (1983) Lr10, Lr23, Lr13, Lr34 +? Norm (1992) Lr1, Lr10, Lr13, Lr16, Lr23, Lr34 Norm (1992) Lr1, Lr10, Lr13, Lr16, Lr23, Lr34 both highly resistance since release both highly resistance since release  Alsen (2000) Lr2a, Lr10, Lr13, Lr23, Lr34 R-MR R-MR  Knudson (2002) Lr3, Lr10, Lr13, Lr16, Lr23, Lr34 Briggs (2002) Lr13, Lr16, Lr30, Lr34 Briggs (2002) Lr13, Lr16, Lr30, Lr34 Both highly resistant Both highly resistant  Marshall (1982) Lr2a, Lr10, Lr13, Lr34 Mod. Susceptible Mod. Susceptible

5. Effective Lr genes in 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

6. South American Landraces  Americano 25e (1918) Lr3, Lr16, LrX1,LrAPR  Americano 44d (1918) 1-2 APR genes THBJ Field THBJ Field  Tc*2/Am. 25e LrAPR ;2- 30 MRMS  Tc*2/Am.44d LrAPR ;23 20 M  Tc*2/Am.44d LrAPR ;2- 20 MRMS

7. U.S. Soft Red Winter Wheat Coker 9663 (1996) Lr9, Lr10, Lr14a Coker 9663 (1996) Lr9, Lr10, Lr14a R-MR R-MR Pioneer 26R61 (1999) Lr13, Lr14b, Lr26 Pioneer 26R61 (1999) Lr13, Lr14b, Lr26 R-MR R-MR

8. Lr34 in U.S. Wheat Hard red spring wheat Hard red spring wheat  Minnesota common 1966-mid 1990s common 1966-mid 1990s FHB resistant cvs. lack Lr34 FHB resistant cvs. lack Lr34  South Dakota - few cvs. with Lr34 few cvs. with Lr34  North Dakota - few cvs. with Lr34 few cvs. with Lr34 TcLr34 Tc

9. Lr34 in U.S. Wheat  Soft red winter wheat - old and new cvs. - not present - not present  Hard red winter wheat - very rare  Western spring wheat - not present TcLr34 Tc CSIRO PCR Marker Tip die back

10. Lr genes in U.S. Wheat Seedling resistance genes Seedling resistance genes - lower ploidy relatives - lower ploidy relatives - common wheat - common wheat Virulent races arise quickly Virulent races arise quickly Lr9, Lr16, Lr26 - still provide some resistance Lr9, Lr16, Lr26 - still provide some resistance Adult Plant Genes Adult Plant Genes Lr34 - not sufficient alone Lr34 - not sufficient alone Lr12 - ineffective Lr12 - ineffective Lr13 - ineffective Lr13 - ineffective Lr23 - characteristics of APR Lr23 - characteristics of APR  Combinations of Lr34 + effective seedling genes = best resistance = best resistance TcLr34 TcLr13 TcLr12 Tc