|Brown Guedira, Gina|
Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/10/2003
Publication Date: 10/8/2003
Citation: Singh, S., Franks, C.D., Liang, L., Brown Guedira, G., Marshall, D., Gill, B., Fritz, A. 2003. Lr41, lr39, and a leaf rust resistance gene from aegilops cylindrica may be allelic and are located on wheat chromosome 2ds. Theoretical and Applied Genetics. 108(4):586-591. Interpretive Summary: Two genes which originated in exotic relatives of common wheat and which impart resistance to the disease leaf rust of wheat were transferred to cultivated wheat. Using cytological and molecular techniques, it was determined that although these two newly discovered genes came from somewhat distantly related species, they were both located on the same chromosomal segment. In addition, they were found to be closely linked to a previously identified leaf rust resistance gene, known as Lr39. Observations of the progeny of crosses between different wheat lines possessing a single copy of each of these genes indicate that all three genes are likely identical.
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 TA 4186 (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.