title: Grasshopper, a long terminal repeat (LTR) retroelement in the phytopathogenic fungus Magnaporthe grisea.
abstract: The fungal phytopathogen Magnaporthe grisea parasitizes a wide variety of gramineous hosts. In the course of investigating the genetic relationship between pathogen genotype and host specificity we identified a retroelement that is present in some strains of M. grisea that infect finger millet and goosegrass (members of the plant genus Eleusine). The element, designated grasshopper (grh), is present in multiple copies and dispersed throughout the genome. DNA sequence analysis showed that grasshopper contains 198 base pair direct, long terminal repeats (LTRs) with features characteristic of retroviral and retrotransposon LTRs. Within the element we identified an open reading frame with sequences homologous to the reverse transcriptase, RNaseH, and integrase domains of retroelement pol genes. Comparison of the open reading frame with sequences from other retroelements showed that grh is related to the gypsy family of retrotransposons. Comparisons of the distribution of the grasshopper element with other dispersed repeated DNA sequences in M. grisea indicated that grasshopper was present in a broadly dispersed subgroup of Eleusine pathogens, suggesting that the element was acquired subsequent to the evolution of this host-specific form. We present arguments that the amplification of different retroelements within populations of M. grisea is a consequence of the clonal organization of the fungal populations.
authors.affiliation: Department of Biological Sciences, Purdue University, West Lafayette, IN 47907.
authors.forename: K F
authors.initials: KF
authors.lastname: Dobinson
authors.forename: R E
authors.initials: RE
authors.lastname: Harris
authors.forename: J E
authors.initials: JE
authors.lastname: Hamer
mesh_terms: D000595:Amino Acid Sequence; D001203:Ascomycota / Q000235:genetics* / Q000302:isolation & purification; D001483:Base Sequence; D004254:DNA Nucleotidyltransferases / Q000235:genetics; D004251:DNA Transposable Elements; D004271:DNA, Fungal / Q000235:genetics; D005800:Genes, Fungal; D019426:Integrases; D008969:Molecular Sequence Data; D012194:RNA-Directed DNA Polymerase / Q000235:genetics; D012091:Repetitive Sequences, Nucleic Acid; D015183:Restriction Mapping; D012190:Retroviridae / Q000235:genetics; D016914:Ribonuclease H / Q000235:genetics; D017386:Sequence Homology, Amino Acid
chemical_list: D004251:DNA Transposable Elements; D004271:DNA, Fungal; D004254:DNA Nucleotidyltransferases; D019426:Integrases; D012194:RNA-Directed DNA Polymerase; D016914:Ribonuclease H