title: Involvement of ethylene in stress-induced expression of the TLC1.1 retrotransposon from Lycopersicon chilense Dun.
abstract: The TLC1 family is one of the four families of long terminal repeat (LTR) retrotransposons identified in the genome of Lycopersicon chilense. Here, we show that this family of retroelements is transcriptionally active and its expression is induced in response to diverse stress conditions such as wounding, protoplast preparation, and high salt concentrations. Several stress-associated signaling molecules, including ethylene, methyl jasmonate, salicylic acid, and 2,4-dichlorophenoxyacetic acid, are capable of inducing TLC1 family expression in vivo. A representative of this family, named TLC1.1, was isolated from a genomic library from L. chilense. Transient expression assays in leaf protoplasts and stably transformed tobacco (Nicotiana tabacum) plants demonstrate that the U3 domain of the 5'-LTR region of this element can drive stress-induced transcriptional activation of the beta-glucuronidase reporter gene. Two 57-bp tandem repeated sequences are found in this region, including an 8-bp motif, ATTTCAAA, previously identified as an ethylene-responsive element box in the promoter region of ethylene-induced genes. Expression analysis of wild-type LTR and single and double ethylene-responsive element box mutants fused to the beta-glucuronidase gene shows that these elements are required for ethylene-responsive gene expression in protoplasts and transgenic plants. We suggest that ethylene-dependent signaling is the main signaling pathway involved in the regulation of the expression of the TLC1.1 element from L. chilense.
authors.affiliation: Instituto de Biología Vegetal y Biotecnología, Universidad de Talca, Talca, Chile.
authors.forename: Gerardo
authors.initials: G
authors.lastname: Tapia
authors.forename: Isabel
authors.initials: I
authors.lastname: Verdugo
authors.forename: Mónica
authors.initials: M
authors.lastname: Yañez
authors.forename: Iván
authors.initials: I
authors.lastname: Ahumada
authors.forename: Cristina
authors.initials: C
authors.lastname: Theoduloz
authors.forename: Cecilia
authors.initials: C
authors.lastname: Cordero
authors.forename: Fernando
authors.initials: F
authors.lastname: Poblete
authors.forename: Enrique
authors.initials: E
authors.lastname: González
authors.forename: Simón
authors.initials: S
authors.lastname: Ruiz-Lara
mesh_terms: D003681:Dehydration; D005030:Ethylenes / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000502:physiology*; D008969:Molecular Sequence Data; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic / Q000502:physiology; D018626:Retroelements; D015398:Signal Transduction; D012965:Sodium Chloride / Q000494:pharmacology; D019657:Solanaceae / Q000187:drug effects / Q000378:metabolism*; D020079:Terminal Repeat Sequences
chemical_list: D005030:Ethylenes; D018626:Retroelements; D012965:Sodium Chloride; C036216:ethylene