title: Analysis of the structure of the AVR1-CO39 avirulence locus in virulent rice-infecting isolates of Magnaporthe grisea.
abstract: The AVR1-CO39 gene that came from a Magnaporthe grisea isolate from weeping lovegrass controls avirulence on the rice cultivar CO39. AVR1-CO39 was not present in the genome of the rice-infecting M. grisea isolate Guyll from French Guyana, suggesting that the gene had been deleted. Molecular analysis of the deletion breakpoints in the AVR1-CO39 locus revealed the presence of a truncated copy of a previously unknown retrotransposon at the left-hand border. At the right-hand border was a truncated copy of another repetitive element that is present at multiple locations in the genome of Guyll. The structures of avr1-CO39 loci were further examined in 45 rice-infecting isolates collected in Brazil, China, Japan, India, Indonesia, Mali, and the Philippines. Most isolates showed no hybridization signal with the AVR1-CO39 probe and had the same locus structure as Guyll. Some isolates from Japan showed a signal with the AVR1-CO39 probe, but the region specifying avirulence activity was rearranged. These findings suggest that widespread virulence to 'CO39' among rice-infecting M. grisea isolates is due to ancestral rearrangements at the AVR1-CO39 locus that may have occurred early in the evolution of pathogenicity to rice.
authors.affiliation: Department of Plant Pathology, University of Wisconsin, Madison 53706, USA.
authors.forename: Mark L
authors.initials: ML
authors.lastname: Farman
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Eto
authors.forename: Tomomi
authors.initials: T
authors.lastname: Nakao
authors.forename: Yukio
authors.initials: Y
authors.lastname: Tosa
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Nakayashiki
authors.forename: Shigeyuki
authors.initials: S
authors.lastname: Mayama
authors.forename: Sally A
authors.initials: SA
authors.lastname: Leong
mesh_terms: D001483:Base Sequence; D001938:Brazil; D002681:China; D002874:Chromosome Mapping; D005800:Genes, Fungal; D005843:Geography; D007564:Japan; D020082:Magnaporthe / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity*; D008969:Molecular Sequence Data; D012275:Oryza / Q000382:microbiology*; D014774:Virulence / Q000235:genetics*