Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 26, 2012
Publication Date: April 26, 2012
Citation: Kolmer, J.A., Lin, M., Bai, G. 2012. Genetics of Leaf Rust Resistance in the Winter Wheat Line CI13227. Crop Science. 52:2166-2172. Interpretive Summary: Wheat is attacked by the rust fungus called Puccinia triticina, which causes the disease wheat leaf rust. There are many different forms or races of the wheat leaf rust fungus that vary in their ability to attack different resistance genes in wheat. Wheat breeders like to use resistance genes in wheat that give resistance to all the different races of the leaf rust fungus. The winter wheat, CI13227, developed at Purdue University was determined to have a gene that gives resistance to all the different races of leaf rust. Another gene that is effective to only certain races of leaf rust was also found in CI13227. These results differed from a previous study with the same wheat which indicated that different genes were responsible for the leaf rust resistance in CI13227. Wheat breeders and plant pathologists can use these results to develop wheat cultivars that are very resistant to the leaf rust disease.
Technical Abstract: The winter wheat line CI13227 with slow rusting resistance to leaf rust was crossed and backcrossed to Thatcher (Tc) wheat. Backcross (BC) F2 families were tested for seedling resistance and segregated in a 1:1 ratio for families that segregated for resistance and families that were homozygous susceptible. BC1F2 resistant seedlings were progeny tested for infection type (IT) as BC1F3 lines and compared for IT with near-isogenic lines of Tc with alleles at the Lr3 locus. The BC1F3 lines and the Tc line with Lr3ka had nearly identical IT. F2 progeny of a resistant BC1F3 plant and a Tc line with Lr3ka did not segregate for IT confirming that CI13227 had an allele at the Lr3 locus. BC1F2 plants from families that were homozygous susceptible as seedlings were tested as adults for leaf rust IT. Resistant BC1F2 adult plants were selected and advanced to BC1F6 by single seed descent. A single BC1F6 plant was crossed with Tc, and the Tc*3/CI13227 population advanced to F6. The F6 RILs were tested for leaf rust resistance at two locations. Molecular mapping with DArT and SSR markers detected a major locus for resistance on chromosome 1BL. A PCR marker specific for Lr46 also mapped in the 1BL region associated with resistance. Quantitative trait loci on 2DS, 2B, and 7BL for slow rusting resistance in CI13227 detected in previous experiments were not detected in this study. CI13227 has seedling resistance gene Lr3ka and likely has the adult plant gene Lr46.