title: Gibberellin metabolism in Vitis vinifera L. during bloom and fruit-set: functional characterization and evolution of grapevine gibberellin oxidases.
abstract: Gibberellins (GAs) are involved in the regulation of flowering and fruit-set in grapes (Vitis vinifera L.), but the molecular mechanisms behind this process are mostly unknown. In this work, the family of grapevine GA oxidases involved in the biosynthesis and deactivation of GAs was characterized. Six putative GA 20-oxidase (GA20ox), three GA 3-oxidase (GA3ox), and eight GA 2-oxidase (GA2ox) proteins, the latter further divided into five C19-GA 2ox and three C20-GA2ox proteins, were identified. Phylogenetic analyses suggest a common origin of the GA3ox and C19-GA2ox groups and challenge previous evolutionary models. In vitro analysis revealed that all GA3ox and GA20ox enzymes prefer substrates of the non-13-hydroxylation pathway. In addition, ectopic expression of GA2ox genes in Arabidopsis thaliana confirmed the activity of their encoded proteins in vivo. The results show that bioactive GA1 accumulates in opening grapevine flowers, whereas at later developmental stages only GA4 is detected in the setting fruit. By studying the expression pattern of the grapevine GA oxidase genes in different organs, and at different stages of flowering and fruit-set, it is proposed that the pool of bioactive GAs is controlled by a fine regulation of the abundance and localization of GA oxidase transcripts.
authors.affiliation: Research and Innovation Centre-Fondazione Edmund Mach, Via E. Mach 1, 38010 S. Michele all'Adige (TN), Italy.
authors.forename: Lisa
authors.initials: L
authors.lastname: Giacomelli
authors.forename: Omar
authors.initials: O
authors.lastname: Rota-Stabelli
authors.forename: Domenico
authors.initials: D
authors.lastname: Masuero
authors.forename: Atiako Kwame
authors.initials: AK
authors.lastname: Acheampong
authors.forename: Marco
authors.initials: M
authors.lastname: Moretto
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Caputi
authors.forename: Urska
authors.initials: U
authors.lastname: Vrhovsek
authors.forename: Claudio
authors.initials: C
authors.lastname: Moser
mesh_terms: D019143:Evolution, Molecular; D035264:Flowers / Q000201:enzymology / Q000235:genetics; D005638:Fruit / Q000201:enzymology / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D005875:Gibberellins / Q000378:metabolism*; D006899:Mixed Function Oxygenases / Q000378:metabolism*; D008954:Models, Biological; D009928:Organ Specificity / Q000235:genetics; D010802:Phylogeny; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity / Q000235:genetics; D027843:Vitis / Q000201:enzymology / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*
chemical_list: D005875:Gibberellins; D012333:RNA, Messenger; D006899:Mixed Function Oxygenases; C089210:gibberellin, 2-oxoglutarate-oxygen oxidoreductase (20-hydroxylating, oxidizing)
keywords: Anthesis; Vitis vinifera.; fruit set; gibberellin 2β-hydroxylase; gibberellin 3β-hydroxylase; gibberellin metabolism; gibberellin oxidase; grapevine; inflorescence