|Kolmer, James - Jim|
Submitted to: Crop Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/21/2004
Publication Date: 2/23/2005
Citation: Helguera, M., Vanzetti, L., Soria, M., Khan, I.A., Kolmer, J.A., Dubcovsky, J. 2005. PCR markers for Triticum speltoides leaf rust resistance gene Lr51 and their use to develop isogenic hard red spring wheat lines. Crop Science. 45:728-734. Interpretive Summary: Certain fungi, known as rusts, can attack wheat and other cereal crops. Leaf rust is an important disease of wheat. Genes for rust resistance in wheat can be used to limit yield losses in wheat due to the leaf rust disease. Biotechnology methods were used to develop molecular markers for rust resistance genes in wheat. Molecular markers can quickly detect the presence of rust resistance genes in wheat, without needing to grow wheat plants and test the plants for resistance to rust. In this study a molecular marker was developed to detect the leaf rust resistance gene Lr51. The molecular marker was used to add rust the resistance gene Lr51 to spring wheats with other leaf rust resistance genes. This molecular marker can be used to add the highly effective leaf rust resistance gene Lr51 to wheat germplasm. Addition of this gene will greatly improve leaf rust resistance in wheat cultivars.
Technical Abstract: New leaf rust resistance genes are needed in wheat to provide additional sources of resistance to the highly variable and dynamic leaf rust pathogen Puccinia triticina. Leaf rust resistance gene Lr51, located within a segment of Triticum speltoides chromosome 1S translocated to the long arm of chromosome 1B of bread wheat, is resistant to the current predominant races of leaf rust in the U.S. The objectives of this study were to determine the genetic length of the translocated 1S segment, develop a PCR marker for Lr51 and use this marker to generate isogenic lines for this gene. Characterization of two translocation lines (F-7-3 and F-7-12) with 10 molecular markers showed that F-7-3 has an interstitial T. speltoides chromosome segment of 14 to 32-cM long including loci XAga7 and Xmwg710 whereas line F-7-12 had a complex series of translocations among chromosomes of homoeologous group 1. Based on the DNA sequence from the A, B, D and S-alleles of the XAga7 locus we designed a Cleavage Amplified Polymorphic Sequence (CAPS) marker. Primers S30-13L and AGA7-759R amplified preferentially the XAga7 1S (819-bp) and 1B alleles (783-bp). These amplification products can be separated in agarose gels after digestion with Pst I or BamH I restriction enzymes. This CAPS marker was validated in a collection of 33 common wheat cultivars and used to develop three hard red spring pairs of isogenic lines using the F-7-3 line as a donor parent. These isogenic lines will be a valuable tool for future evaluation of the effect of this chromosome introgression on agronomic performance and quality.