title: Nitric oxide mediates the indole acetic acid induction activation of a mitogen-activated protein kinase cascade involved in adventitious root development.
abstract: Recently, it was demonstrated that nitric oxide (NO) and cGMP are involved in the auxin response during the adventitious rooting process in cucumber (Cucumis sativus; Pagnussat et al., 2002, 2003). However, not much is known about the complex molecular network operating during the cell proliferation and morphogenesis triggered by auxins and NO in that process. Anatomical studies showed that formation of adventitious root primordia was clearly detected in indole acetic acid (IAA)- and NO-treated cucumber explants, while neither cell proliferation nor differentiation into root primordia could be observed in control explants 3 d after primary root was removed. In order to go further with signal transduction mechanisms that operate during IAA- and NO-induced adventitious root formation, experiments were designed to test the involvement of a mitogen-activated protein kinase (MAPK) cascade in that process. Cucumber explants were treated with the NO-donor sodium nitroprusside (SNP) or with SNP plus the specific NO-scavenger cPTIO. Protein extracts from those explants were assayed for protein kinase (PK) activity by using myelin basic protein (MBP) as substrate in both in vitro and in-gel assays. The activation of a PK of approximately 48 kD could be detected 1 d after NO treatment with a maximal activation after 3 d of treatment. In control explants, a PK activity was detected only after 4 d of treatment. The MBP-kinase activity was also detected in extracts from IAA-treated explants, while no signal was observed in IAA + cPTIO treatments. The PK activity could be inhibited by the cell-permeable MAPK kinase inhibitor PD098059, suggesting that the NO-dependent MBP-kinase activity is a MAPK. Furthermore, when PD098059 was administered to explants treated with SNP or IAA, it produced a delay in root emergence and a dose-dependent reduction in root number. Altogether, our results suggest that a MAPK signaling cascade is activated during the adventitious rooting process induced by IAA in a NO-mediated but cGMP-independent pathway. The activation of MAPKs is discussed in relation to the cell responses modulating mitotic process.
authors.affiliation: Instituto de Investigaciones Biológicas, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, CC1245 7600 Mar del Plata, Argentina.
authors.forename: Gabriela Carolina
authors.initials: GC
authors.lastname: Pagnussat
authors.forename: María Luciana
authors.initials: ML
authors.lastname: Lanteri
authors.forename: María Cristina
authors.initials: MC
authors.lastname: Lombardo
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Lamattina
mesh_terms: D018553:Cucumis sativus / Q000187:drug effects / Q000201:enzymology / Q000254:growth & development; D017869:Cyclic GMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D007210:Indoleacetic Acids / Q000494:pharmacology*; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008938:Mitosis / Q000187:drug effects; D009569:Nitric Oxide / Q000378:metabolism* / Q000494:pharmacology; D009599:Nitroprusside / Q000494:pharmacology; D010937:Plant Growth Regulators / Q000494:pharmacology; D018517:Plant Roots / Q000166:cytology / Q000187:drug effects / Q000254:growth & development*; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D004791:Enzyme Inhibitors; D005419:Flavonoids; D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; D009599:Nitroprusside; D009569:Nitric Oxide; C030737:indoleacetic acid; D017869:Cyclic GMP-Dependent Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D020929:Mitogen-Activated Protein Kinase Kinases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one