Submitted to: Keystone Symposia
Publication Type: Abstract Only
Publication Acceptance Date: 1/30/2001
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: The barley Mla locus confers multiple resistance specificities to the powdery mildew fungus, Blumeria (=Erysiphe) graminis f. sp. hordei. Interspersed within the 240-kb Mla complex are three families of resistance gene homologs (RGHs). Probes from the Mla-RGH1 family were used to identify three classes of cDNAs. The first is predicted to encode a full- length CC-NBS-LRR protein and the other two are truncated variants. Utilizing a cosmid that contains a gene corresponding to the full-length candidate cDNA, a single-cell expression assay was used to demonstrate complementation of AvrMla6-dependent resistance to B. graminis in barley and wheat. This assay was also used to substantiate previous genetic data that the Mla6 allele requires the signaling pathway component, Rar1, for function. Comparison of Mla6 and the Rar1-independent Mla1 protein reveals 91.2% sequence identity, demonstrating that highly related CC-NBS-LRR proteins encoded by alleles at the Mla locus can dictate different powdery mildew recognition specificities and require distinct signaling components. Research supported by USDA-NRI/CGP grant 98-35300-6170.