title: Stress-induced mobility of OPHIO1 and OPHIO2, DNA transposons of the Dutch elm disease fungi.
abstract: The mobility of transposable elements (TEs) can contribute to genome plasticity, under- or over-expression of genes and ectopic recombination. The data collected in this study provide evidence of stress-induced mobility of OPHIO1 and OPHIO2 transposons, recently detected in Ophiostoma ulmi and O. novo-ulmi, the causal agents of Dutch elm disease (DED). The analyses of OPHIO UTRs and TIRs indicated the presence of two potential binding site motifs and a heat shock protein (hsp) promoter which could be involved in the mobility of OPHIO1 following a heat shock stress. The exact position of the hsp promoter was determined by 5' RACE PCR. After confirmation of the expression by RT-PCR of both OPHIO1 and OPHIO2 transposases in the absence of stress factors, we tested two experimental procedures to induce mobility of OPHIO TEs: (1) an exogenous (cloned) copy of OPHIO1 was introduced into the O. novo-ulmi subsp. americana strain W2 (OPHIO1 free strain) to give mutant strain W2:OPHIO1. After exposure of W2:OPHIO1 to a 55 degrees C heat shock treatment, some of the survivors showed signs of incomplete transposition (excision without reinsertion) of OPHIO1. (2) The O. novo-ulmi subsp. novo-ulmi strain AST27, introgressed from O. ulmi and carrying a distinct endogenous copy of OPHIO2 (OPHIO2-int.), was subjected to a series of abiotic stress treatments. Although a promoter sequence could not be identified, both exposures to UV light and to a 4 degrees C cold treatment caused perfect excision of OPHIO2-int. In contrast to OPHIO1, heat shock stress did not induce OPHIO2-int. mobility. Taken together, these results allow us to hypothesize a potential interspecific invasion of OPHIO transposons due to their mobility in Ophiostoma spp.
authors.affiliation: Centre d'étude de forêt (CEF), Université LAVAL, Que., Canada G1K7P4.
authors.forename: Guillaume F
authors.initials: GF
authors.lastname: Bouvet
authors.forename: Volker
authors.initials: V
authors.lastname: Jacobi
authors.forename: Karine V
authors.initials: KV
authors.lastname: Plourde
authors.forename: Louis
authors.initials: L
authors.lastname: Bernier
mesh_terms: D020121:5' Untranslated Regions; D001203:Ascomycota / Q000235:genetics* / Q000528:radiation effects; D001483:Base Sequence; D001665:Binding Sites; D003080:Cold Temperature; D004251:DNA Transposable Elements; D006358:Hot Temperature; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D012331:RNA, Fungal / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D011995:Recombination, Genetic; D019895:Transposases / Q000096:biosynthesis; D014466:Ultraviolet Rays
chemical_list: D020121:5' Untranslated Regions; D004251:DNA Transposable Elements; D012331:RNA, Fungal; D012333:RNA, Messenger; D019895:Transposases