The MLA6 coiled‐coil, NBS‐LRR protein confers AvrMla6‐dependent resistance specificity to Blumeria graminis f. sp. hordei in barley and wheat

• Published in: The Plant journal : for cell and molecular biology Vol. 25; no. 3; pp. 335 - 348
• Main Authors: Halterman, Dennis, Zhou, Fasong, Wei, Fusheng, Wise, Roger P., Schulze‐Lefert, Paul
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Science Ltd 01.02.2001; Blackwell Science
• Subjects: Agronomy. Soil science and plant productions; alternative splicing; Amino Acid Sequence; amino acid sequences; Ascomycota; Ascomycota - pathogenicity; AvrMla6 gene; Base Sequence; Biological and medical sciences; Blumeria graminis; Blumeria graminis f. sp. hordei; CC-NBS-LRR protein; CC‐NBS‐LRR; complementary DNA; disease resistance; DNA Primers; DNA, Complementary; Fundamental and applied biological sciences. Psychology; gene expression; Genetic Complementation Test; genetics; Genetics and breeding of economic plants; heterologous resistance specificity; Hordeum; Hordeum - microbiology; Hordeum vulgare; loci; microbiology; Mla gene; MLA1 protein; Mla6 gene; MLA6 protein; Molecular Sequence Data; multigene family; NBS-LRR protein; nucleotide sequences; pathogenicity; Pest resistance; physiology; Plant pathogens; plant proteins; Plant Proteins - genetics; Plant Proteins - physiology; Rar1 gene; Rar1‐dependent signaling; Sequence Homology, Amino Acid; Triticum; Triticum - microbiology; Triticum aestivum; Varietal selection. Specialized plant breeding, plant breeding aims; Alternative splicing; Monocotyledones; Plant pathogen; Hordeum vulgare; Cereal crop; Fungus resistance; Fungi; Signal transduction; Specificity; Gene; Gramineae; Angiospermae; Ascomycetes; Spermatophyta; Complementation; Erysiphe graminis f. hordei; Models; Aminoacid sequence; Triticum aestivum; Thallophyta
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1046/j.1365-313x.2001.00982.x

Summary The barley Mla locus confers multiple resistance specificities to the obligate fungal biotroph, 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 class is predicted to encode a full‐length CC‐NBS‐LRR protein and the other two classes contain alternatively spliced, truncated variants. Utilizing a cosmid that contains a gene corresponding to the full‐length candidate cDNA, two single‐cell expression assays were used to demonstrate complementation of AvrMla6‐dependent, resistance specificity to B. graminis in barley and wheat. The first of these assays was also used to substantiate previous genetic data that the Mla6 allele requires the signaling pathway component, Rar1, for function. Computational analysis of MLA6 and the Rar1‐independent, MLA1 protein reveals 91.2% identity and shows that the LRR domain is subject to diversifying selection. Our findings demonstrate that highly related CC‐NBS‐LRR proteins encoded by alleles of the Mla locus can dictate similar powdery mildew resistance phenotypes yet still require distinct downstream signaling components.