Submitted to: Journal of Theoretical and Applied Genetics
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/15/2004
Publication Date: 10/20/2004
Citation: Singh, S., Franks, C.D., Huang, L., Brown Guedira, G.L., Marshall, D.S., Gill, B.S. 2004. Lr41, lr39, and a leaf rust resistance gene from aegilops cylindrica may be allelic and are located on wheat chromosome 2ds. Journal of Theoretical and Applied Genetics. 108:586-591. Interpretive Summary: The ancestral species of wheat make-up a rich source of undeployed disease resistance genes. Previous research has identified the leaf rust resistance genes, Lr39 and Lr41, as being derived from goat-grass (Aegilops tauschii), a diploid species. We have shown in the present research that the same gene, or a very closely related allele of Lr39 and/or Lr41, is also present in a different ancestral species, Aegilops cylindrica, which is a tetraploid. This is the first instance in wheat, where a gene has been found to be present in two different ancestors, and both have been transferred to common wheat.
Technical Abstract: The leaf rust resistance gene Lr41 in wheat germplasm KS90WGRC10 and a resistance gene in wheat breeding line WX93D246-R-1 were transferred to Triticum aestivum from Aegilops tauschii and Ae. cylindrica, respectively. The leaf rust resistance gene in WX93D246-R-1 was located on wheat chromosome 2D by monosomic analysis. Molecular marker analysis of F2 plants from non-critical crosses determined that this gene is 11.2 cM distal to marker Xgwm210 on the short arm of 2D. No susceptible plants were detected in a population of 300 F2 plants from a cross between WX93D246-R-1 and TA4186 (Lr39), suggesting that the gene in WX93D246-R-1 is the same as, or closely linked to, Lr39. In addition, no susceptible plants were detected in a population of 180 F2 plants from the cross between KS90WGRC10 and WX93D246-R-1. The resistance gene in KS90WGRC10, Lr41, was previously reported to be located on wheat chromosome 1D. In this study, no genetic association was found between Lr41 and 51 markers located on chromosome 1D. A population of 110 F3 lines from a cross between KS90WGRC10 and TAM 107 was evaluated with polymorphic SSR markers from chromosome 2D and marker Xgdm35 was found to be 1.9 cM proximal to Lr41. When evaluated with diverse isolates of Puccinia triticina, similar reactions were observed on WX93D246-R-1, KS90WGRC10, and TA 4186. The results of mapping, allelism, and race specificity test indicate that these germplasms likely have the same gene for resistance to leaf rust.