The Gibberellins

Content: List of Contributors xv    Preface xvii    1 Signal Achievements in Gibberellin Research: The Second Half-Century 1  Valerie M. Sponsel    1.1 Introduction 1    1.2 Gibberellin biosynthesis 6    1.3 Gibberellin signalling 17    1.4 Physiological responses to gibberellins 25    References 29    2 Gibberellin Biosynthesis in Higher Plants 37  Peter Hedden    2.1 Introduction 37    2.2 Synthesis of ent-kaurene 39    2.2.1 Formation of trans-geranylgeranyl diphosphate 39    2.2.2 Formation of ent-kaurene from trans-geranylgeranyl diphosphate 40    2.3 Reactions catalysed by cytochrome P450 mono-oxygenases 42    2.4 Reactions catalysed by 2-oxoglutarate-dependent dioxygenases 45    2.5 Sites of gibberellin biosynthesis 49    2.6 Regulation of gibberellin biosynthesis 50    2.6.1 Developmental control 50    2.6.2 Gibberellin homoeostasis 51    2.6.3 Regulation by other hormones 54    2.6.4 Regulation by environmental factors 55    2.7 Concluding remarks 59    Acknowledgements 60    References 60    3 Inactivation Processes 73  Hiroshi Magome and Yuji Kamiya    3.1 Introduction 73    3.2 Gibberellin inactivation 75    3.2.1 Gibberellin 2-oxidase 75    3.2.2 Gibberellin methyltransferase 77    3.2.3 Gibberellin 16,17-oxidase 78    3.2.4 Gibberellin 13-oxidase and 12  -oxidase 78    3.2.5 Conjugation with sugar 80    3.3 Regulation of gibberellin inactivation 80    3.3.1 Developmental regulation 81    3.3.2 Gibberellin homoeostasis 82    3.3.3 Regulation by other hormones 83    3.3.4 Environmental regulation 84    3.4 Concluding remarks 87    References 88    4 Gibberellin Transport 95  Jonathan Dayan    4.1 Introduction 95    4.2 Gibberellins can be translocated along plant bodies 96    4.3 Gibberellin transport in seeds 100    4.4 Pattern of gibberellin biosynthesis in transport analysis 101    4.5 Grafting experiments 103    4.6 Significance for secondary growth 104    4.7 Orientation of gibberellin signal flow: source and sink tissues 107    4.8 Monitoring intra- and intercellular gibberellin concentration 110    4.9 Conclusion: new aspects for gibberellin transport 111    4.9.1 Potential transporters 111    4.9.2 Analysis through perception 112    4.9.3 Links to sugar transport 112    Acknowledgements 113    References 114    5 Gibberellins in Fungi, Bacteria and Lower Plants: Biosynthesis, Function and Evolution 121  Bettina Tudzynski, Lena Studt and Maria Cecilia Rojas    5.1 Introduction 122    5.2 Gibberellin biosynthesis in fungi 122    5.2.1 The biosynthetic pathway in F. fujikuroi: genes and enzymes 122    5.2.2 Gibberellin production in distantly related fungi 126    5.2.3 Evolution of the gibberellin biosynthetic gene cluster in fungi 128    5.2.4 The role of gibberellins in plant infection 131    5.2.5 Strain improvement 132    5.3 Gibberellin biosynthesis in bacteria 133    5.3.1 Free-living rhizobacteria 133    5.3.2 Symbiotic rhizobacteria: genes and reactions of the gibberellin biosynthetic pathway 134    5.3.3 Function and evolution 137    5.4 Gibberellin biosynthesis and signalling components in lower plants 139    5.5 Concluding remarks 143    References 144    6 Gibberellin Hormone Signal Perception: Down-Regulating DELLA Repressors of Plant Growth and Development 153  Sven K. Nelson and Camille M. Steber    6.1 Introduction 154    6.2 DELLA proteins are repressors of gibberellin responses 154    6.3 Gibberellin signalling lifts DELLA repression of gibberellin responses 157    6.4 The gibberellin receptor GID1 (GA-INSENSITIVE DWARF1) 159    6.5 The structural requirements for gibberellin binding by GID1 161    6.6 The structural requirements for the GID1-DELLA protein   protein interaction 162    6.7 The DELLA destruction model: negative regulation of DELLA repressors by SLY1/GID2 and the ubiquitin-proteasome pathway 166    6.8 Regulation of DELLA by phosphorylation and O-GlcNAc modification 169    6.9 Evidence for gibberellin-independent DELLA regulation 173    6.10 Evidence for gibberellin signalling without DELLA destruction 175    6.11 Concluding remarks 177    Acknowledgements 179    References 179    7 DELLA Proteins: Master Regulators of Gibberellin-Responsive Growth and Development 189  Stephen G. Thomas, Miguel A. Blazquez and David Alabadi    7.1 Introduction 190    7.2 DELLAs regulate downstream gibberellin signalling 191    7.3 Gibberellins relieve DELLA-growth repression by targeting their degradation 193    7.4 Functional diversification of DELLA genes 194    7.5 DELLA activity invokes rapid changes in the transcriptome 197    7.6 DELLA proteins activate transcription 198    7.7 DELLAs regulate transcription by physical interaction with transcriptional regulators 199    7.7.1 DELLAs sequester bona fide TFs by physical interaction 200    7.7.2 DELLAs interact with TFs in the context of promoters 204    7.7.3 DELLAs interact with other transcriptional regulators 206    7.7.4 DELLAs regulate chromatin dynamics 208    7.8 A non-genomic response regulated by DELLAs 209    7.9 Analysis of DELLA protein structure-function 210    7.10 GAMYB: A transcriptional regulator of gibberellin responses during cereal grain germination and pollen development 213    7.10.1 GAMYB positively regulates gene expression in cereal aleurone cells 214    7.10.2 GAMYB regulates gibberellin-dependent anther development 216    7.11 Concluding remarks 217    Acknowledgements 218    References 218    8 Interactions Between Gibberellins and other Hormones 229  John J. Ross, Asemeh Miraghazadeh, Amelia H. Beckett, Laura J. Quittenden and Erin L. McAdam    8.1 Introduction 229    8.2 Interactions involving effects of other hormones on gibberellin levels 230    8.2.1 Auxin promotes gibberellin biosynthesis 230    8.2.2 Ethylene inhibits gibberellin biosynthesis 231    8.2.3 Do gibberellin and abscisic acid inhibit each other   s synthesis? 232    8.2.4 Do brassinosteroids act by affecting gibberellin levels? 234    8.2.5 Possible effects of other hormones on gibberellin synthesis 234    8.3 Interactions between hormone signal transduction pathways 234    8.3.1 Do other hormones affect DELLA stability? 235    8.3.2 DELLAs interact with proteins from the signaling pathways of other hormones 237    8.4 Gibberellins and auxin transport 245    8.5 Conclusion 246    Acknowledgements 247    References 247    9 Gibberellins and Seed Germination 253    Terezie Urbanova and Gerhard Leubner-Metzger    9.1 Introduction 254    9.2 Spatiotemporal expression of gibberellin metabolism during Brassicaceae seed germination 254    9.3 Gibberellin signalling and seed germination 264    9.3.1 The GID1ac and GID1b pathways in seeds 264    9.3.2 DELLA proteins and seed germination 268    9.4 Gibberellin and abiotic stress factors: thermoinhibition of seed germination 270    9.5 Gibberellin and biotic stress factors: allelochemical interference of gibberellin biosynthesis during seed germination 273    9.6 Conclusions and perspectives 276    Acknowledgements 277    References 277    10 Gibberellins and Plant Vegetative Growth 285  Cristina Martinez, Ana Espinosa-Ruiz and Salome Prat    10.1 Introduction 285    10.2 Gibberellins and shoot development 288    10.2.1 Control of SAM function and leaf size 289    10.2.2 Elongation of the hypocotyl 290    10.2.3 Apical hook formation 295    10.3 Gibberellin function in root development 298    10.3.1 Hormonal control of root growth 298    10.3.2 Gibberellin signalling from the endodermis 302    10.3.3 DELLAs downstream signalling in the root 304    10.3.4 DELLAs promote mycorrhizal symbiosis 306    10.4 Growth under unfavourable conditions 308    10.4.1 DELLAs promote resistance to abiotic stress 308    10.4.2 DELLAs and biotic stress 310    10.5 Concluding remarks 311    References 312    11 Gibberellins and Plant Reproduction 323  Andrew R.G. Plackett and Zoe A. Wilson    11.1 Introduction 323    11.2 The floral transition 324    11.2.1 Gibberellin promotes flowering through multiple interacting pathways 324    11.2.2 Sites of gibberellin biosynthesis and action during the floral transition 329    11.2.3 Gibberellin and flowering in perennial species 331    11.3 Floral development 331    11.3.1 Floral patterning and early development 332    11.3.2 Gibberellin and fertility 334    11.4 Seed and fruit development 340    11.4.1 Fruit development 341    11.4.2 Embryo and seed development 345    Acknowledgements 348    References 348    12 Chemical Regulators of Gibberellin Status and their Application in Plant Production 359  Wilhelm Rademacher    12.1 Introduction 359    12.2 Gibberellins 361    12.3 Inhibitors of gibberellin biosynthesis 363    12.3.1 Quaternary ammonium compounds 365    12.3.2 Compounds with a nitrogen-containing heterocycle 366    12.3.3 Structural mimics of 2-oxoglutaric acid 369    12.3.4 16,17-Dihydro-gibberellins 371    12.4 Uses for gibberellins and inhibitors of gibberellin biosynthesis in crop production 372    12.4.1 Wheat, barley, rye, oats and other small-grain cereals 373    12.4.2 Rice 376    12.4.3 Sugarcane 377    12.4.4 Pasture and turf grasses 377    12.4.5 Oilseed rape 379    12.4.6 Cotton 379    12.4.7 Peanuts 381    12.4.8 Opium poppy 382    12.4.9 Fruit trees growing in temperate climate 382    12.4.10 Fruit and nut trees growing in subtropical and tropical climates 385    12.4.11 Grapevines 387    12.4.12 Ornamentals 389    12.4.13 Hybrid seed production 391    12.5 Outlook 391    References 391    13 Genetic Control of Gibberellin Metabolism and Signalling in Crop Improvement 405  Andrew L. Phillips    13.1 Introduction 405    13.2 The REDUCED HEIGHT-1 (Rht-1) alleles of wheat 406    13.2.1 Pleiotropic effects of Rht-1 alleles 410    13.2.2 Rht-1 orthologues in other crop species 412    13.3 The SEMI-DWARF-1(SD-1) alleles of rice 413    13.4 The ELONGATED UPPERMOST INTERNODE (EUI) gene of rice 415    13.5 Commercially useful alleles of other genes from the gibberellin pathway 416    13.6 Transgenic approaches to manipulation of gibberellin-dependent processes in crops 419    13.6.1 Cereals 419    13.6.2 Other crop species 420    13.7 Conclusions 423    Acknowledgements 424    References 424    Appendix The structures of the gibberellins 431    Index 437