Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/15/2000
Publication Date: 8/1/2000
Citation: RAUPP,W.L., SINGH,S., BROWN GUEDIRA,G.L., GILL,B.S., CYTOGENETIC AND MOLECULAR MAPPING OF THE LEAF RUST RESISTANCE GENE LR39 IN WHEAT, THEORETICAL AND APPLIED GENETICS, 2000. Interpretive Summary: Leaf rust of wheat is a serious disease that can occur in all regions where wheat is grown. New genes for resistance to this disease are constantly needed in order to deal with the rapidly evolving pathogen population. Wild relatives of wheat are a valuable source of new resistance genes. In this study, we transferred a leaf rust resistance gene from the wild species Ae. tauschii into cultivated wheat. Genetic analysis of this gene determined that it is different from genes previously transferred from this wild species. The gene designation Lr39 was therefore assigned to this gene. We genetically mapped Lr39 on wheat chromosome 2DS using cytogenetic and molecular techniques.
Technical Abstract: Leaf rust, caused by the fungus Puccinia triticina Eriks, is one of the most serious diseases of wheat (Triticum aestivum AABBDD, 2n=6x=42) worldwide. Growing resistant cultivars is an efficient and economical method of reducing losses to leaf rust. Here we report a new leaf rust resistance gene, Lr39, transferred from Aegilops tauschii into common wheat. Lr39 conditions both seedling and adult plant resistance to the leaf rust pathogen. The inter- and intra-chromosomal mapping of the Lr39 gene showed that it is different from all previously described Lr genes. We used monosomic analysis for the inter-chromosomal mapping. The monosomic and ditelosomic analysis indicated the Lr39 is independent of the centromere on the short arm of chromosome 2D. Eight microsatellite markers for 2DS were used for linkage analysis on a population of 57 F2 plants derived from a cross of an Ae. tauschii-derived wheat, cv. Wichita line TA4186 (possessing Lr39), with Wichita monosomics for the D-genome chromosomes. The microsatellite marker analysis confirmed the location of the gene on 2DS. Three markers were polymorphic and linked to the gene. The closest marker Xgwm210 mapped 10.7cM from Lr39. The location of Lr39 near the telomere of 2DS distinguishes it from the Lr2 and Lr22 loci, which are located on 2DS proximal to Xgwm210.