title: The gibberellin biosynthetic genes AtGA20ox1 and AtGA20ox2 act, partially redundantly, to promote growth and development throughout the Arabidopsis life cycle.
abstract: The activity of the gibberellin (GA) biosynthetic enzymes GA 20-oxidases (GA20ox) is of particular importance in determining GA concentration in many plant species. In Arabidopsis these enzymes are encoded by a family of five genes: AtGA20ox1-AtGA20ox5. Transcript analysis indicated that they have different expression patterns and may thus participate differentially in GA-regulated developmental processes. We have used reverse genetics to determine the physiological roles of AtGA20ox1 and AtGA20ox2, the most highly expressed GA20ox genes during vegetative and early reproductive development. AtGA20ox1 and AtGA20ox2 act redundantly to promote hypocotyl and internode elongation, flowering time, elongation of anther filaments, the number of seeds that develop per silique and elongation of siliques, with AtGA20ox1 making the greater contribution to internode and filament elongation, and AtGA20ox2 making the greater contribution to flowering time and silique length. Pollination of the double mutant with wild-type pollen indicated that the GA promoting silique elongation is of maternal origin. The ga20ox2 phenotype revealed that GA promotes the number of stem internodes that elongate upon bolting, and does so independently of its effect on internode elongation. Comparison of the phenotype of the double mutant with that of the highly GA-deficient ga1-3 mutant indicates that other GA20ox genes contribute to all the developmental processes examined, and, in some cases such as root growth and leaf expansion, make major contributions, as these processes were unaffected in the double mutant. In addition, the effects of the mutations are mitigated by the homeostatic mechanism that acts on expression of other GA dioxygenase and GID1 receptor genes.
authors: Plant Science Department, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK.
authors: Ivo
authors: I
authors: Rieu
authors: Omar
authors: O
authors: Ruiz-Rivero
authors: Nieves
authors: N
authors: Fernandez-Garcia
authors: Jayne
authors: J
authors: Griffiths
authors: Stephen J
authors: SJ
authors: Powers
authors: Fan
authors: F
authors: Gong
authors: Terezie
authors: T
authors: Linhartova
authors: Sven
authors: S
authors: Eriksson
authors: Ove
authors: O
authors: Nilsson
authors: Stephen G
authors: SG
authors: Thomas
authors: Andrew L
authors: AL
authors: Phillips
authors: Peter
authors: P
authors: Hedden
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D035264:Flowers / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D018525:Germination / Q000235:genetics / Q000502:physiology; D005875:Gibberellins / Q000096:biosynthesis*; D006899:Mixed Function Oxygenases / Q000235:genetics / Q000378:metabolism*; D018547:Plant Stems / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D030821:Plants, Genetically Modified; D016133:Polymerase Chain Reaction; D012098:Reproduction / Q000235:genetics / Q000502:physiology; D036226:Seedlings / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D012639:Seeds / Q000235:genetics / Q000254:growth & development / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D005875:Gibberellins; D006899:Mixed Function Oxygenases; C089210:gibberellin, 2-oxoglutarate-oxygen oxidoreductase (20-hydroxylating, oxidizing)