title: Mechanisms of nitric-oxide-induced increase of free cytosolic Ca2+ concentration in Nicotiana plumbaginifolia cells.
abstract: In this study, we investigated a role for nitric oxide (NO) in mediating the elevation of the free cytosolic Ca(2+) concentration ([Ca(2+)](cyt)) in plants using Nicotiana plumbaginifolia cells expressing the Ca(2+) reporter apoaequorin. Hyperosmotic stress induced a fast increase of [Ca(2+)](cyt) which was strongly reduced by pretreating cell suspensions with the NO scavenger carboxy PTIO, indicating that NO mediates [Ca(2+)](cyt) changes in plant cells challenged by abiotic stress. Accordingly, treatment of transgenic N. plumbaginifolia cells with the NO donor diethylamine NONOate was followed by a transient increase of [Ca(2+)](cyt) sensitive to plasma membrane Ca(2+) channel inhibitors and antagonist of cyclic ADP ribose. We provided evidence that NO might activate plasma membrane Ca(2+) channels by inducing a rapid and transient plasma membrane depolarization. Furthermore, NO-induced elevation of [Ca(2+)](cyt) was suppressed by the kinase inhibitor staurosporine, suggesting that NO enhances [Ca(2+)](cyt) by promoting phosphorylation-dependent events. This result was further supported by the demonstration that the NO donor induced the activation of a 42-kDa protein kinase which belongs to SnRK2 families and corresponds to Nicotiana tabacum osmotic-stress-activated protein kinase (NtOSAK). Interestingly, NtOSAK was activated in response to hyperosmotic stress through a NO-dependent process, supporting the hypothesis that NO also promotes protein kinase activation during physiological processes.
authors.affiliation: Unité Mixte de Recherche INRA 1088/CNRS 5184/Université de Bourgogne, Plante-Microbe-Environnement, Dijon, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Lamotte
authors.forename: Cécile
authors.initials: C
authors.lastname: Courtois
authors.forename: Grazyna
authors.initials: G
authors.lastname: Dobrowolska
authors.forename: Angélique
authors.initials: A
authors.lastname: Besson
authors.forename: Alain
authors.initials: A
authors.lastname: Pugin
authors.forename: David
authors.initials: D
authors.lastname: Wendehenne
mesh_terms: D002118:Calcium / Q000737:chemistry / Q000378:metabolism*; D002413:Cations, Divalent / Q000737:chemistry; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism*; D008970:Molecular Weight; D009569:Nitric Oxide / Q000378:metabolism*; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism; D019657:Solanaceae / Q000378:metabolism*
chemical_list: D002413:Cations, Divalent; D009569:Nitric Oxide; D011494:Protein Kinases; D002118:Calcium