title: Signal transduction in lemon seedlings in the hypersensitive response against Alternaria alternata: participation of calmodulin, G-protein and protein kinases.
abstract: The development of an effective hypersensitive response (HR) in any plant system relies, not only in their gene composition and expression, but also on an effective and rapid signal transduction system. Lemon seedlings induce the phenylpropanoid pathway, which results in the de novo biosynthesis of the phytoalexin scoparone, as part of the hypersensitive response against Alternaria alternata. In order to elucidate some of the signaling elements that participate in the development of HR in lemon seedlings, we used several compounds that are known as activators or inhibitors of signal transduction elements in plants or in animal cells. Lemon seedlings treated either with cholera toxin or with phorbol 12-myristate 13-acetate (PMA), in the absence of A. alternata induced phenylalanine ammonia-lyase (PAL, E. C. 4.3.1.5) and the synthesis of scoparone, suggesting the participation of a G-protein and of a serine/threonine kinase, respectively, in signal transduction. The use of trifluoperazine (TFP), W-7, staurosporine, lavendustin A or 2,5-dihydroximethyl cinnamate (DHMC) prevented PAL induction as well as scoparone biosynthesis in response to the fungal inoculation, thus allowing us to infer the participation of Calmodulin (CaM), of serine/threonine and of tyrosine protein kinases (TPK) for signal transduction in Citrus limon in response to A. alternata.
authors.affiliation: Laboratorio de Bioquímica, Facultad Ciencias de la Salud, Universidad Nacional Andrés Bello.
authors.forename: Ximena
authors.initials: X
authors.lastname: Ortega
authors.forename: Rubén
authors.initials: R
authors.lastname: Polanco
authors.forename: Patricia
authors.initials: P
authors.lastname: Castañeda
authors.forename: Luz M
authors.initials: LM
authors.lastname: Perez
mesh_terms: D000528:Alternaria; D002147:Calmodulin / Q000378:metabolism; D002772:Cholera Toxin / Q000494:pharmacology; D002957:Citrus / Q000382:microbiology / Q000502:physiology*; D003374:Coumarins / Q000378:metabolism*; D004790:Enzyme Induction / Q000187:drug effects; D020962:Heterotrimeric GTP-Binding Proteins / Q000378:metabolism; D010650:Phenylalanine Ammonia-Lyase / Q000378:metabolism*; D010766:Phosphorylation; D010936:Plant Extracts / Q000096:biosynthesis*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D012639:Seeds / Q000187:drug effects / Q000382:microbiology / Q000502:physiology; D012717:Sesquiterpenes; D015398:Signal Transduction / Q000187:drug effects; D013729:Terpenes; D014268:Trifluoperazine / Q000494:pharmacology; D000094162:Phytoalexins
chemical_list: D002147:Calmodulin; D003374:Coumarins; D010936:Plant Extracts; D012717:Sesquiterpenes; D013729:Terpenes; D014268:Trifluoperazine; D002772:Cholera Toxin; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; D020962:Heterotrimeric GTP-Binding Proteins; D010650:Phenylalanine Ammonia-Lyase; C018145:scoparone; D000094162:Phytoalexins