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Title: MOLECULAR CHARACTERIZATION OF AVR1-CO39 FROM MAGNAPORTHE GRISEA

Author
item Leong, Sally
item FARMAN, MARK - UNIVERSITY OF WISCONSIN
item PUNEKAR, NARAYAN - INDIAN INSTITUTE OF TECHN
item TOSA, YUKIO - KOBE UNIVERSITY, JAPAN

Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: 7/1/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: A gene conferring cultivar-specific interactions with rice cultivar CO39 was isolated from Magnaporthe grisea strain 2539 using a map-based cloning approach. The AVR1-CO39 locus was delimited to a 1.05kb region by subcloning and transformation of Guy11, a strain virulent on CO39, to avirulence. DNA sequence analysis revealed 3 small open reading frames of 45, 77 and 91 amino acids in length. The sequence surrounding the ATG of the 3rd open reading frame matched 4 out of 5 of the conserved bases found in fungal translational start sites and contained a hydrophobic amino terminus punctuated by a lysine in position 2 and 2 putative cleavage sites for removal of the signal peptide. A 4th reading frame was identified on the opposite strand, however, the sequence surrounding the ATG contained only 2 matches with the fungal consensus sequence. Site-directed mutations in all 3 open reading frames on one strand were created in order to assess their role in avirulence. The translational start codon of each open reading frame was converted to TTT; mutations in open reading frames 1 and 3 led to a loss of avirulence. Frameshift mutations in open reading frames 1 and 3 also led to a loss of avirulence while mutation of open reading frame 2 did not. Taken together, these data suggest a role for open reading frames 1 and 3. The distribution of AVR1-CO39 was investigated by probing genomic DNA from a large sample of host-specific forms of M.grisea. The data to date indicate that isolates affecting rice, Digitaria and wheat lack AVR1-CO39 while about half of the isolates surveyed from Eleucine contain homologs of the gene. Moreover, a detailed analysis of the AVR1-CO39 locus from rice isolate Guy11 indicated that 20kb of DNA corresponding to,&containing the AVR1-CO39 locus of 2539 was absent.