ARS | Publication request: FUNCTIONAL ANALYSIS OF MLA-MEDIATED POWDERY MILDEW RESISTANCE IN BARLEY

Submitted to: Plant Molecular Biology International Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: June 21, 2000
Publication Date: N/A

Technical Abstract: Powdery mildew of barley, caused by Erysiphe graminis f. sp. hordei, is a model system for investigating the mechanism of gene-for-gene specificity between large-genome cereals and obligate-fungal pathogens. The Mla (powdery mildew) resistance-gene cluster is positioned on the short arm of chromosome 5 (1H). AFLP-, RAPD-, STS-, and RFLP-derived markers were used to saturate the Mla region in a high-resolution, recombinant population segregating for the [Mla6 + Mla14] and [Mla13 + Ml-Ru3] resistance specificities. These Mla specificities have been delimited to a 240-kb physical interval bridged by two overlapping BAC clones. Genetic and physical analysis of Mla-spanning BACs has revealed eleven NBS-LRR resistance gene homologs (RGHs), seven chymotrypsin inhibitor (CI) genes, and several BARE-1 copia-like retro elements in this gene-rich, recombination-suppressed region. cDNA library screening was used to identify expressed RGH sequences from both Mla6 and Mla13 backgrounds. Numerous alternative transcripts were detected in the 5' UTR and the 3' coding region of Mla cDNAs. Fast-neutron derived, accelerated cell-death mutants are being used to target signaling events in the barley-powdery mildew interaction. Research supported by USDA-NRI/CGP grant 98-35300- 6169.