Analysis of the Developmental Roles of the Arabidopsis Gibberellin 20-Oxidases Demonstrates That GA20ox1, -2, and -3 Are the Dominant Paralogs

• DOI: 10.1105/tpc.111.095109
• Publication Date: 2012-03-17T04:32:38Z
• Authors: Andrew R.G. Plackett; Stephen J. Powers; Nieves Fernandez-...; Terezie Urbanova; Yumiko Takebayashi; Mitsunori Seo; Yusuke Jikumaru; Reyes Benlloch; Ove Nilsson; Omar Ruiz-Rivero; Andrew L. Phillips; Zoe A. Wilson; Stephen G. Thomas; Peter Hedden
• Keywords: 2. Zero hunger; 0303 health sciences; Plant Infertility; Arabidopsis Proteins; Arabidopsis; Gene Expression Regulation, Developmental; Flowers; Plants, Genetically Modified; Gibberellins; Mixed Function Oxygenases; 03 medical and health sciences; Gene Expression Regulation, Plant; Mutation; Phylogeny

Gibberellin (GA) biosynthesis is necessary for normal plant development, with later GA biosynthetic stages being governed by multigene families. Arabidopsis thaliana contains five 20-oxidase (GA20ox) genes, and past work has demonstrated the importance of GA20ox1 -2 growth fertility. Here, we show through systematic mutant analysis that GA20ox1, -2, -3 are dominant paralogs; their absence results in severe dwarfism almost complete loss In vitro revealed GA20ox4 full GA20ox activity, but GA20ox5 catalyzes only first two reactions sequence which GA12 converted to GA9. GA20ox3 functions entirely redundantly at most developmental stages, including floral transition, while -5 have very minor roles. These supported gene expression patterns promoter:β-glucuronidase reporter lines. We demonstrate fertility highly sensitive concentration, significant effects on organ anther both deficiency overdose impact Loss activity causes arrest, tapetum failing degrade. Some phenotypic recovery late flowers GA-deficient mutants, ga1-3, indicated involvement non-GA pathways development.