title: Ovary-derived precursor gibberellin A9 is essential for female flower development in cucumber.
abstract: Gibberellins (GAs) are hormones that control many aspects of plant development, including flowering. It is well known that stamen is the source of GAs that regulate male and bisexual flower development. However, little is known about the role of GAs in female flower development. In cucumber, high levels of GA precursors are present in ovaries and high levels of bioactive GA4are identified in sepals/petals, reflecting the expression of GA 20-oxidase and 3-oxidase in these organs, respectively. Here, we show that the biologically inactive precursor GA9moves from ovaries to sepal/petal tissues where it is converted to the bioactive GA4necessary for female flower development. Transient expression of a catabolic GA 2-oxidase from pumpkin in cucumber ovaries decreases GA9and GA4levels and arrests the development of female flowers, and this can be restored by application of GA9to petals thus confirming its function. Given that bioactive GAs can promote sex reversion of female flowers, movement of biologically inactive precursors, instead of the hormone itself, might help to maintain floral organ identity, ensuring fruit and seed production.
authors: TU Braunschweig, Institut für Pflanzenbiologie, 38106 Braunschweig, Germany.
authors: Maria João
authors: 0000-0002-3898-6130
authors: MJ
authors: Pimenta Lange
authors: TU Braunschweig, Institut für Pflanzenbiologie, 38106 Braunschweig, Germany theo.lange@tu-bs.de.
authors: Theo
authors: 0000-0003-1294-2647
authors: T
authors: Lange
mesh_terms: D018553:Cucumis sativus / Q000254:growth & development*; D028464:Cucurbita / Q000201:enzymology / Q000235:genetics; D035264:Flowers / Q000254:growth & development* / Q000378:metabolism*; D005875:Gibberellins / Q000235:genetics / Q000378:metabolism*; D006899:Mixed Function Oxygenases / Q000378:metabolism*; D063245:Plant Development / Q000235:genetics / Q000502:physiology; D030821:Plants, Genetically Modified / Q000235:genetics; D015398:Signal Transduction
chemical_list: D005875:Gibberellins; D006899:Mixed Function Oxygenases; C089210:gibberellin, 2-oxoglutarate-oxygen oxidoreductase (20-hydroxylating, oxidizing); C108186:gibberellin 3beta-hydroxylase
keywords: Cucumis; Female flower development; Gibberellin signalling; Gibberellin transport