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Title: Fine mapping of the Lr46/Yr29 locus in wheat

item Brown-Guedira, Gina
item Fellers, John
item Cregan, Perry
item Bowden, Robert - Bob

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 12/20/2007
Publication Date: 12/20/2007
Citation: Perugini, L., Brown Guedira, G.L., Mateos-Herandez, M., Fellers, J.P., Song, Q., Cregan, P.B., Hulbert, S., Bowden, R.L., Singh, F. 2007. Fine mapping of the Lr46/Yr29 locus in wheat. Meeting Abstract.

Interpretive Summary: N/A

Technical Abstract: Rust diseases, including leaf rust (Puccinia triticina), stripe rust (P. striiformis f. sp. tritici), and stem rust (P. graminis f. sp. tritici) are globally the most important diseases of wheat. Genetic resistance is the best form of control but frequent race changes typically render new varieties susceptible within a few years after release. For typical resistance genes, the mechanism of resistance and the basis of race specificity are due to gene-for-gene interactions. However, some disease resistance genes are thought to be durable because they are not dependent on the recognition of a single Avr gene product from the pathogen by an R-gene. The adult plant resistance gene Lr46 has provided non-race specific resistance to leaf rust that has remained effective for more than 30 years. The gene also has a pleiotropic effect on resistance to stripe rust (Yr29). Using recombinant chromosome substitution line populations, we previously located Lr46 on the terminal region of the long arm of chromosome 1B that is syntenic to chromosome 5L of rice. To fine map the Lr46 gene region, high resolution mapping (HRM) populations were developed that represent 4100 gametes. The EST-derived STS marker XSTS3680 that co-segregated with Lr46 in the original mapping populations was mapped 0.15 cM distal to Lr46 in the HRM populations. A BAC contig of the Lr46 region is being constructed. New SSR and SNP markers identified from the BAC clones and linked to Lr46 have been evaluated on a set of diverse wheat lines to determine their usefulness for marker-assisted selection. Gene expression studies can be complement map-based cloning efforts since expression data can be used for identifying candidate genes, identifying expression markers, and for generating and testing hypotheses about genetic mechanisms. To identify transcripts associated with Lr46-mediated adult plant resistance, the Affymetrix Wheat GeneChip Microarray was used to identify transcriptional changes in isogenic lines with and without Lr46. Considering the increasing worldwide use of Lr46 and other adult-plant genes for durable rust resistance, it is essential to obtain a greater understanding of their mechanisms of resistance. It is also essential to obtain the best possible markers for breeding for durable resistance.