title: Low levels of gibberellic acid control the biosynthesis of ajmalicine in Catharanthus roseus cell suspension cultures.
abstract: In periwinkle cell suspensions, amounts of gibberellic acid ranging from 10 ( - 10) M to 10 ( - 7) M significantly antagonized, in a dose-dependant manner, the stimulation of ajmalicine biosynthesis by cytokinins (CKs). This inhibitory effect was strictly correlated with the abolition of the expression of two genes encoding enzymes of the monoterpenoid indole alkaloid (MIA) biosynthetic pathway and was normally upregulated after CK treatments. Moreover, low concentrations of the gibberellin biosynthesis inhibitor paclobutrazol could reverse the inhibitory effects of low auxin levels on ajmalicine accumulation in the cells. On the other hand, gibberellic acid could not affect the expression of two type-A response regulators considered to be CK primary response genes in periwinkle cells. The antagonistic effects of gibberellins and cytokinins on MIA biosynthesis and their possible impact on elements of the signal transduction are discussed.
authors.affiliation: Biomolécules et Biotechnologies végétales, Faculté de Pharmacie, Université de Tours, Tours, France.
authors.forename: Aniça
authors.initials: A
authors.lastname: Amini
authors.forename: Gaëlle
authors.initials: G
authors.lastname: Glévarec
authors.forename: Françoise
authors.initials: F
authors.lastname: Andreu
authors.forename: Marc
authors.initials: M
authors.lastname: Rideau
authors.forename: Joël
authors.initials: J
authors.lastname: Crèche
mesh_terms: D030008:Catharanthus / Q000378:metabolism*; D018929:Cell Culture Techniques; D003583:Cytokinins / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D017343:Genes, Plant; D005875:Gibberellins / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000378:metabolism*; D007210:Indoleacetic Acids / Q000378:metabolism; D010937:Plant Growth Regulators / Q000037:antagonists & inhibitors / Q000378:metabolism*; D012313:RNA / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D046948:Secologanin Tryptamine Alkaloids / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D014230:Triazoles / Q000494:pharmacology
chemical_list: D003583:Cytokinins; D005875:Gibberellins; D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; D046948:Secologanin Tryptamine Alkaloids; D014230:Triazoles; C005709:raubasine; D012313:RNA; C053370:paclobutrazol; C007842:gibberellic acid