ARS | Publication request: RECOGNITION SPECIFICITY AND POST-TRANSCRIPTIONAL REGULATION OF MLA (POWDERY MILDEW) RESISTANCE ALLELES IN BARLEY

Submitted to: Plant Genome Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: January 16, 2002
Publication Date: N/A

Technical Abstract: Powdery mildew of barley, caused by Blumeria graminis f. sp. hordei (Bgh), is a model system for investigating the mechanisms of gene-for-gene interactions between large genome cereals and obligate fungal pathogens. Approximately 30 resistance specificities have been identified at the Mla locus. Using a single-cell transient assay, we have determined that the CC-NBS-LRR proteins encoded by the cloned Mla6 and Mla13 alleles confer resistance specificity to isolates of Bgh that possess AvrMla6 and AvrMla13, respectively. Domain swaps of the regions encoding the LRRs of Mla6 and Mla13 result in changes in specificity. The high sequence similarity (90-95%) between cloned Mla alleles has facilitated the PCR amplification of the LRR regions from alternate alleles for use in other complementation tests. Mla6 and Mla13 both contain small upstream reading frames (SMURFs) within their 5' UTRs. SMURFs within the 5' UTR are present tin 5-10% of eukaryotic mRNAs and are thought to control translation or tissue-specific expression of the parent protein within the cell (Willis A.E., 1999, Int. J. Biochem. Cell Biol. 31, 73-86). Using an in vitro transcription/translation assay with the five classes of Mla13 UTRs fused with luciferase, we have shown that mutation of the SMURF start codon leads to a change in luciferase production.