title: Ultraviolet-B activates components of the systemin signaling pathway in Lycopersicon peruvianum suspension-cultured cells.
abstract: Among the early responses of Lycopersicon peruvianum suspension-cultured cells to the polypeptide wound signal systemin are the alkalinization of the culture medium and the activation of a 48-kDa mitogen-activated protein kinase (MAPK). Here, we report that both responses are induced in the cells by exposure to ultraviolet-B (UV-B) radiation. Suramin, an inhibitor of systemin receptor function, strongly inhibited the UV-B-induced medium alkalinization and MAPK activity. The UV-B response was also reduced when cells were initially treated with systemin or the systemin antagonist Ala-17-systemin, which competitively inhibits binding of systemin to the systemin receptor. Cells that were initially treated with either UV-B or systemin exhibited a strongly reduced response to a subsequent elicitation with systemin. The desensitization was transient, reaching a maximum at 30-60 min after the initial treatment. Several hours later, depending on the initial UV-B dose or systemin concentration, the cells regained their initial responsiveness. When cells were irradiated with low doses of UV-B and subsequently treated with systemin, the UV-B response reached levels higher than the response without UV-B treatment. The data provide evidence for an involvement of the systemin receptor and/or systemin-responsive signaling elements in the UV-B response.
authors.affiliation: Institution Department of Biological Sciences, University of South Carolina, Columbia, South Carolina 29208, USA.
authors.forename: Roopa Devi
authors.initials: RD
authors.lastname: Yalamanchili
authors.forename: Johannes W
authors.initials: JW
authors.lastname: Stratmann
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000409:Alanine / Q000737:chemistry; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D006027:Glycosides / Q000494:pharmacology; D018551:Solanum lycopersicum / Q000378:metabolism* / Q000528:radiation effects*; D010455:Peptides / Q000737:chemistry / Q000378:metabolism*; D015398:Signal Transduction; D013498:Suramin / Q000494:pharmacology; D013997:Time Factors; D014466:Ultraviolet Rays
chemical_list: D006027:Glycosides; D010455:Peptides; C007808:fusicoccin; C073704:systemin; D013498:Suramin; D000251:Adenosine Triphosphatases; D000409:Alanine