Cell-Autonomous Expression of Barley Mla1 Confers Race-Specific Resistance to the Powdery Mildew Fungus via a Rar1-Independent Signaling Pathway
Open Access
- 1 February 2001
- journal article
- Published by Oxford University Press (OUP) in Plant Cell
- Vol. 13 (2) , 337-350
- https://doi.org/10.1105/tpc.13.2.337
Abstract
The barley Mla locus encodes 28 characterized resistance specificities to the biotrophic fungal pathogen barley powdery mildew. We describe a single-cell transient expression assay using entire cosmid DNAs to pinpoint Mla1 within the complex 240-kb Mla locus. The MLA1 cDNA encodes a 108-kD protein containing an N-terminal coiled-coil structure, a central nucleotide binding domain, and a C-terminal leucine-rich repeat region; it also contains a second short open reading frame at the 5′ end that has a possible regulatory function. Although most Mla-encoded resistance specificities require Rar1 for their function, we used the single-cell expression system to demonstrate that Mla1 triggers full resistance in the presence of the severely defective rar1-2 mutant allele. Wheat contains an ortholog of barley Mla, designated TaMla, that is tightly linked to (0.7 centimorgan) but distinct from a tested resistance specificity at the complex Pm3 locus to wheat powdery mildew. Thus, the most polymorphic powdery mildew resistance loci in barley and wheat may have evolved in parallel at two closely linked homeoloci. Barley Mla1 expressed in wheat using the single-cell transformation system failed to trigger a response to any of the wheat powdery mildew Avr genes tested, indicating that AvrMla1 is not genetically fixed in wheat mildew strains.Keywords
This publication has 26 references indexed in Scilit:
- Interaction Analyses of Genes Required for Resistance Responses to Powdery Mildew in Barley Reveal Distinct Pathways Leading to Leaf Cell Death.Plant Cell, 1997
- The Barley Mlo Gene: A Novel Control Element of Plant Pathogen ResistanceCell, 1997
- Effect of three suppressors on the expression of powdery mildew resistance genes in barleyGenome, 1996
- The product of the tobacco mosaic virus resistance gene N: Similarity to toll and the interleukin-1 receptorCell, 1994
- Nar-1 and Nar-2, Two Loci Required for Mla12-Specified Race-Specific Resistance to Powdery Mildew in Barley.Plant Cell, 1994
- Initiation codons within 5′-leaders of mRNAs as regulators of translationTrends in Biochemical Sciences, 1994
- TRANSLATIONAL CONTROL IN MAMMALIAN CELLSAnnual Review of Biochemistry, 1991
- Predicting Coiled Coils from Protein SequencesScience, 1991
- MAPMAKER: An interactive computer package for constructing primary genetic linkage maps of experimental and natural populationsGenomics, 1987
- Preparation of barley storage protein, hordein, for analytical sodium dodecyl sulfate-polyacrylamide gel electrophoresisAnalytical Biochemistry, 1981