title: Long-term submergence-induced elongation in Rumex palustris requires abscisic acid-dependent biosynthesis of gibberellin1.
abstract: Rumex palustris (polygonceae) responds to complete submergence with enhanced elongation of its youngest petioles. This process requires the presence of gibberellin (GA) and is associated with an increase in the concentration of GA1 in elongating petioles. We have examined how GA biosynthesis was regulated in submerged plants. Therefore, cDNAs encoding GA-biosynthetic enzymes GA 20-oxidase and GA 3-oxidase, and the GA-deactivating enzyme GA 2-oxidase were cloned from R. palustris and the kinetics of transcription of the corresponding genes was determined during a 24 h submergence period. The submergence-induced elongation response could be separated into several phases: (1) during the first phase of 4 h, petiole elongation was insensitive to GA; (2) from 4 to 6 h onward growth was limited by GA; and (3) from 15 h onward underwater elongation was dependent, but not limited by GA. Submergence induced an increase of GA1 concentration, as well as enhanced transcript levels of RpGA3ox1. Exogenous abscisic acid repressed the transcript levels of RpGA20ox1 and RpGA3ox1 and thus inhibited the submergence-induced increase in GA1. Abscisic acid had no effect on the tissue responsiveness to GA.
authors.affiliation: Plant Ecophysiology, Institute of Environmental Biology, Utrecht University, Utrecht, Sorbonnelaan 16, 3584 CA, The Netherlands.
authors.forename: Joris J
authors.initials: JJ
authors.lastname: Benschop
authors.forename: Jordi
authors.initials: J
authors.lastname: Bou
authors.forename: Anton J M
authors.initials: AJ
authors.lastname: Peeters
authors.forename: Niels
authors.initials: N
authors.lastname: Wagemaker
authors.forename: Kerstin
authors.initials: K
authors.lastname: Gühl
authors.forename: Dennis
authors.initials: D
authors.lastname: Ward
authors.forename: Peter
authors.initials: P
authors.lastname: Hedden
authors.forename: Thomas
authors.initials: T
authors.lastname: Moritz
authors.forename: Laurentius A C J
authors.initials: LA
authors.lastname: Voesenek
mesh_terms: D000040:Abscisic Acid / Q000494:pharmacology / Q000502:physiology*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005875:Gibberellins / Q000096:biosynthesis* / Q000494:pharmacology / Q000502:physiology; D007101:Immersion; D006899:Mixed Function Oxygenases / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D010937:Plant Growth Regulators / Q000096:biosynthesis* / Q000494:pharmacology / Q000502:physiology; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D031804:Rumex / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D014230:Triazoles / Q000494:pharmacology; D014867:Water
chemical_list: D005875:Gibberellins; D010937:Plant Growth Regulators; D012333:RNA, Messenger; D014230:Triazoles; D014867:Water; C053370:paclobutrazol; D000040:Abscisic Acid; D006899:Mixed Function Oxygenases