Developmental Biology of Flowering Plants

The study of the development of flowering plants may be said to be in the throes of a revolution. The literature on the subject is extensive and continues to grow rapidly as new discoveries pile one on top of the other; moreover, these striking advances in our knowledge have put plant developmental biology well ahead of other aspects of the study of plants. This has come about after a period of neglect and stagnation in the field and has been triggered by the power of recombinant DNA technology to analyze genetic information and by a fruitful cross-fertilization between physiology, genetics, and molecular biology. Whereas considerations of developmental phenomena were at one time largely restricted to the structure and physiology of a wide selection of plants, recent molecular and genetic approaches are focused on one or two model systems. Notwithstanding the difficulty of having to relate developmental mechanisms in a few experimentally attractive models to the enormous range of plants, the use of model systems has gained wide accep­ tance. This book is intended to meet the need for a unified account of the general principles of development of flowering plants representing structural, physiolog­ ical, biochemical, genetic, and molecular perspectives. It arose out of the revision and upgrading of an undergraduate course in plant development that I have taught here at The Ohio State University for more than 20 years.

1. Introduction to Plant Developmental Biology.- General References.- 1 Seed to Seedling.- 2. Seed Germination.- 1. Nucleic Acid Metabolism.- DNA Synthesis.- RNA and Protein Synthesis.- Long-Lived mRNA.- 2. Protein Metabolism.- Use of Stored mRNAs for Protein Synthesis.- Newly Synthesized mRNAs and Proteins.- 3. Mobilization of Stored Food Reserves.- Regulation of ?-Amylase Genes by Gibberellic Acid.- Final Phases of Endosperm Dissolution.- Interaction of Gibberellic Acid and Abscisic Acid.- 4. Summary and Conclusions.- Further Reading.- References.- 3. Seedling Growth.- 1. Tropisms.- Gravitropism.- Phototropism.- Thigmotropism.- 2. Photomorphogenesis of the Seedling.- Hypocotyl and Internode Growth.- Regulation of Photomorphogenesis.- 3. Hormonal Control of Seedling Growth.- Auxins.- Ethylene.- Gibberellins.- Cytokinins, Abscisic Acid, and Brassinosteroids.- Apical Dominance.- 4. Gene Expression During Seedling Growth.- 5. Summary and Conclusions.- Further Reading.- References.- 2 Seedling to the Adult Plant.- 4. Growth and Differentiation of the Shoot.- 1. Organization of the Shoot Apex.- Cytological and Molecular Analysis of the Shoot Apical Meristem.- Autonomy of the Meristem.- 2. Regulation of Cell Fate in the Meristem.- 3. Tissue Differentiation in the Shoot.- Vascular Tissue Differentiation in the Shoot Apex.- Xylem Regeneration in Stem Internodes, Calluses, and Isolated Cells.- Phloem Differentiation.- 4. Summary and Conclusions.- Further Reading.- References.- 5. Leaf Growth and Differentiation.- 1. Leaf Determination and Development.- Determination of Leaf Primordia.- Postinitiation Development of Leaves.- 2. Evolution of Leaf Form.- Heteroblasty.- Heterophylly.- 3. Differentiation of Leaf Cells.- Epidermis.- Mesophyll.- 4. Senescence and Abscission of Leaves.- 5. Summary and Conclusions.- Further Reading.- References.- 6. Root Growth and Development.- 1. The Root Apical Meristem.- Autonomy of the Root Apical Meristem.- Pattern Formation in the Root Meristem.- Cell Division, Cell Expansion, and Cell Elongation in the Root Meristem.- 2. Differentiation of the Root.- Vascular Tissue Differentiation.- Root Hair Formation.- Lateral Root Initiation.- 3. Regulation of Root Growth.- 4. Root-Microbe Interactions.- 5. Summary and Conclusions.- Further Reading.- References.- 3 Reproduction.- 7. Floral Evocation and Development of the Floral Meristem.- 1. Acquisition of the Competence to Flower.- Control of Floral Meristem Identity.- Floral Evocation in Differentiated Cells.- 2. Physiology of Floral Evocation.- Photoperiodic Control of Flowering.- Temperature Control of Flowering.- 3. Molecular Control of Floral Evocation.- Cellular Changes During Evocation.- Isolation of Genes Involved in Flowering.- 4. Summary and Conclusions.- Further Reading.- References.- 8. Formation of Floral Organs.- 1. Determination of Floral Organs.- Genetics of Floral Organ Determination.- Organ Determination in Unisexual Flowers.- Floral-Organ-Specific Polypeptides.- 2. Homeotic Mutants.- Manipulation of Floral Organ Differentiation in Arabidopsis.- Homeotic Mutations in Antirrhinum and Other Plants.- Cloning and Characterization of Floral-Organ-Identity Genes.- 3. Summary and Conclusions.- Further Reading.- References.- 9. Microsporogenesis and Formation of the Male Gametophyte.- 1. Anther Differentiation.- Tapetum.- Microsporogenesis.- 2. Pollen Development and Maturation.- The First Pollen Mitosis.- Gene Expression During Pollen Development.- Male Sterility and Pollen Abortion.- 3. Male Gametogenesis.- Division of the Generative Cell and Formation of the Male Germ Unit.- Pollen Germination.- Structure and Growth of the Pollen Tube.- 4. Summary and Conclusions.- Further Reading.- References.- 10. Megasporogenesis and Formation of the Embryo Sac.- 1. Ovule Determination and Development.- 2. Megasporogenesis.- 3. Organization of the Embryo Sac.- Structure of the Embryo Sac Cells.- Gene Function During Megagametogenesis.- 4. Summary and Conclusions.- Further Reading.- References.- 11. Pollen-Pistil Interactions and Fertilization.- 1. Pollen-Stigma Interactions and Pollen Tube Guidance.- Pollen Recognition by the Stigma.- Pollen Tube Traffic in the Style.- The Final Push: Guidance of Pollen Tubes to the Ovules.- 2. Self-Incompatibility.- Structural and Biochemical Aspects.- Molecular Aspects of Gametophytic Self-Incompatibility.- Molecular Aspects of Sporophytic Self-Incompatibility.- 3. Double Fertilization.- 4. In Vitro Fertilization.- 5. Summary and Conclusions.- Further Reading.- References.- 4 Seed and Fruit Formation.- 12. Endosperm Development and Embryogenesis.- 1. Endosperm.- 2. Embryo.- Becoming Multicellular.- Ultrastructural and Nuclear Cytology.- Cell Lineage During Late Embryo Development.- 3. Nutrition and Growth of Embryos.- Heterotrophic Nutrition.- Embryo Culture.- 4. Gene Action During Embryogenesis.- Changes in Gene Expression Programs.- Embryo-Defective Mutants.- Embryo-Pattern Mutants.- 5. Storage Proteins of the Endosperm and the Embryo.- Endosperm Storage Proteins.- Embryo Storage Proteins.- Storage Protein Gene Expression in Transgenic Systems.- 6. Summary and Conclusions.- Further Reading.- References.- 13. Fruit Growth and Ripening.- 1. Fruit Growth.- 2. Fruit Ripening.- Biochemistry of Ripening.- Molecular Biology of Ripening.- 3. Role of Ethylene in Fruit Ripening.- 4. Summary and Conclusions.- Further Reading.- References.- 14. Dormancy of Seeds and Buds.- 1. Induction of Dormancy in Seeds.- Development of Dormancy.- Role of ABA in Seed Desiccation and Dormancy.- Gene Expression During Dormancy.- 2. Overcoming Seed Dormancy.- After-Ripening of Seeds.- Phytochrome Control.- 3. Bud Dormancy.- 4. Summary and Conclusions.- Further Reading.- References.- 5 Alternative Developmental Strategies.- 15. Embryogenic Development of Somatic Cells and Pollen Grains.- 1. Somatic Embryogenesis.- Role of Secreted Molecules.- Role of Embryonic Proteins.- Genetic and Molecular Dissection of Somatic Embryogenesis.- 2. Pollen Embryogenesis.- Cytology of Pollen Embryogenesis.- Genetics and Molecular Biology of Pollen Embryogenesis.- 3. Summary and Conclusions.- Further Reading.- References.- 16. Abnormal Plant Growth.- 1. Callus Morphogenesis.- 2. Crown Gall Tumors.- Role of the Ti Plasmid.- The Process of T-DNA Transfer.- T-DNA Genes and Tumor Phenotypes.- Mediation of Growth Hormones in Oncogenic Functions.- Crown Gall Teratomas and Tumor Reversal.- 3. Hairy Root Disease.- 4. Summary and Conclusions.- Further Reading.- References.