Understanding Flowers and Flowering An Intergrated Approach

by Glover, Beverly

• ISBN13: 9780198565963
• ISBN10: 0198565968
• Format: Paperback
• Copyright: 2008-01-30
• Publisher: Oxford University Press

Summary

Flowers are the beautiful and complex reproductive structures of the angiosperms, one of the most diverse and successful groups of living organisms. The underlying thesis of this book is that to fully understand plant development (and why flowers differ in shape, structure and color), it is necessary to understand why it is advantageous for them to look like they do. Conversely, in order to fully understand plant ecology, it is necessary to appreciate how floral structures have adapted and evolved. Uniquely, this book addresses flowers and flowering from both a molecular genetic perspective (considering flower induction, development and self-incompatibility) and an ecological perspective (looking at the selective pressures placed on plants by pollinators, and the consequences for animal-plant co-evolution). Understanding Flowers and Flowering first considers the evolution of flowers and the history of research into their development. This is followed by a detailed description of the processes which lead to flower production in model plants. The book then examines how flowers differ in shape, structure and color, and how these differences are generated. Finally it assesses the role of these various aspects of floral biology in attracting pollinators and ensuring successful reproduction. In so doing, it provides the first truly integrated study of the topic - one that discusses both the how? and why? of flowering plant reproductive biology. The breadth of coverage and integrated approach makes this advanced textbook an ideal choice for anyone interested in any aspect of floral biology. It will be particularly suitable for graduate level students taking courses in plant development, ecology, evolution, and reproductive biology.

Author Biography

Beverley Glover was educated at the University of St. Andrews and the John Innes Centre. She has been based in the Department of Plant Sciences at the University of Cambridge since 1996, where her research interests include the molecular genetic control of plant development and the evolution of floral features which enhance attractiveness to pollinators.

Table of Contents

Preface	p. v
Introduction	p. 1
The Evolution of Flowers	p. 3
The origin of flowering plants	p. 3
Early reproductive structures	p. 7
The first flowers	p. 7
Floral diversification	p. 8
Historical Interpretations of Flower Induction and Flower Development	p. 10
The foliar theory of the flower	p. 10
The foliar theory in an evolutionary context	p. 15
The transition to flowering	p. 15
Developmental explanations of floral induction	p. 16
Environmental explanations of floral induction	p. 16
The florigen problem	p. 19
The Molecular Mechanisms of Flowering: Induction and Development	p. 21
Induction of Flowering	p. 23
Flower Induction in Arabidopsis thaliana	p. 25
Arabidopsis thaliana as a model system for the study of flowering	p. 25
Flowering-time mutants	p. 30
The Autonomous Pathways for Floral Inhibition and Induction	p. 35
The floral inhibition pathway	p. 35
The autonomous induction pathway	p. 39
Other endogenous factors which influence flowering time	p. 41
The Photoperiodic Pathway of Floral Induction	p. 43
Sensing daylight	p. 43
Measuring time	p. 48
Integrating light and clock signals	p. 50
The Vernalization Pathway of Floral Induction and the Role of Gibberellin	p. 52
The vernalization promotion pathway	p. 52
The gibberellin promotion pathway	p. 56
Does gibberellin act in the vernalization promotion pathway as well as independently?	p. 58
Integrating the Arabidopsis thaliana Flower Induction Pathways and Assessing the Extent to Which the Model Is Ubiquitous	p. 59
Integrating the flowering-time pathways	p. 59
The Arabidopsis flowering-time model in other species	p. 64
Development of Flowers	p. 69
Changes at the Shoot Apical Meristem in Response to Floral Induction	p. 71
Physiological changes at the shoot apical meristem	p. 71
Shoot apical meristem anatomy	p. 72
Gene expression patterns in the shoot apical meristem	p. 73
Floral meristem identity genes act downstream of the flowering-time integrators	p. 74
Floral meristem identity genes	p. 74
Development of the Floral Organs	p. 83
The original ABC model of flower development	p. 83
The role of D function genes	p. 90
The role of E function genes	p. 90
The role of cadastral genes	p. 92
The quartet model of organ identity	p. 94
The ABC Model in Evolution	p. 95
Evolutionary history of MADS box transcription factors	p. 95
ABC model in gymnosperms?	p. 96
ABC model in monocots?	p. 98
Variations on the ABC model	p. 101
Function and Development of Gametophytes	p. 103
Alternation of generations in multicellular organisms	p. 103
The angiosperm female gametophyte	p. 105
The angiosperm male gametophyte	p. 107
Events following pollination	p. 109
Preventing Self-fertilization	p. 111
Reducing self-pollination in a hermaphroditic flower	p. 111
Monoecy	p. 113
Dioecy	p. 114
Self-incompatibility (SI)	p. 115
Sporophytic self-incompatibility (SSI)	p. 116
Gametophytic self-incompatibility (GSI)	p. 119
Heteromorphic self-incompatibility	p. 120
Pollination Success: Molecular and Ecological Interactions	p. 123
How and Why Does Floral Form Vary?	p. 125
Why Are Flowers Different? Pollination Syndromes-The Theory	p. 127
Cross pollination	p. 127
Abiotic pollen vectors	p. 127
Biotic pollen vectors	p. 129
Principles underlying the pollination syndrome concept	p. 129
The pollination syndromes	p. 130
Changing Floral Shape and Structure	p. 138
Changing corolla size	p. 138
Changing corolla symmetry	p. 140
Changing petal shape	p. 143
Generating a composite inflorescence	p. 145
Colouring the Flower	p. 147
Colour as a signal	p. 147
Plant pigments	p. 148
Carotenoid synthesis	p. 149
Flavonoid synthesis	p. 151
Betalains	p. 156
Enhancing Flower Colour	p. 158
Mixing pigments	p. 158
Co-pigmentation	p. 158
Regulation of pigment distribution	p. 159
The effects of metal ions	p. 162
The importance of pH	p. 163
The role of petal cell shape	p. 165
The Influence of Pollinators on Floral Form	p. 169
Are Flowers under Selective Pressure to Increase Pollinator Attention?	p. 171
Competition for pollinator attention	p. 171
Facilitation of pollination	p. 172
Techniques for investigating the role of pollinator attention in limiting fitness	p. 172
Evidence based on fruit and seed set following hand pollination	p. 175
Evidence from mixed species plots	p. 176
Analysis of character traits potentially displaced by pollination competition	p. 177
Do Pollinators Discriminate between Different Floral Forms?	p. 181
What pollinators see	p. 181
What pollinators sense in other ways	p. 183
Discrimination between petals of different colours	p. 184
Discrimination between corollas of different sizes	p. 189
Discrimination between zygomorphic and actinomorphic flowers	p. 190
Discrimination between flowers with different petal cell shapes	p. 190
Discrimination between flowers on the basis of scent	p. 191
Pollination Syndromes-The Evidence	p. 192
Historical context	p. 192
Putting the assumptions together	p. 193
Evidence for pollination syndromes	p. 195
Evidence against pollination syndromes	p. 197
The most effective pollinator?	p. 198
Epilogue	p. 201
References	p. 203
Index	p. 223
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