Hormonal Regulation of Development II : The Functions of Hormones from the Level of the Cell to the Whole Plant

This is the second of the set of three volumes in the Encyclopedia of Plant Physiology, New Series, that will cover the area of the hormonal regulation of plant growth and development. The overall plan for the set assumes that this area of plant physiology is sufficiently mature for a review of current knowl­ edge to be organized in terms of unifying principles and processes. Reviews in the past have generally treated each class of hormone individually, but this set of volumes is subdivided according to the properties common to all classes. Such an organization permits the examination of the hypothesis that differing classes of hormones, acting according to common principles, are determinants of processes and phases in plant development. Also in keeping with this theme, a plant hormone is defined as a compound with the properties held in common by the native members of the recognized classes of hormone. Current knowledge of the hormonal regulation of plant development is grouped so that the three volumes consider advancing levels of organizational complexity, viz: molecular and subcellular; cells, tissues, organs, and the plant as an organized whole; and the plant in relation to its environment.

1 Hormonal Regulatory Systems in Plants.- 1.1 Introduction.- 1.1.1 The Concept of the Plant Hormone as a Chemical Messenger.- 1.1.2 Types of Hormones.- 1.2 Hormone Messenger Systems.- 1.2.1 Common Difficulties with Single Hormonal Controls.- 1.2.2 Is a Hormone Always a Hormone?.- 1.2.3 Further Complications in the Hormone Concept.- 1.2.4 Regulatory Sites in Hormonal Controls.- 1.2.5 Patterns in Multiple Hormonal Control.- 1.2.6 Complications Arising from Compartmentation.- 1.3 Analysis of Hormonal Controls.- 1.3.1 Two Major Approaches from the Past.- 1.3.2 Analyses of Hormone Systems.- 1.4 Conclusions.- 1.4.1 The Complexity of Hormonal Controls.- 1.4.2 Nonhormonal Correlative Controls.- 1.4.3 Evolutionary Plasticity of Hormonal Controls.- 1.4.4 The Future.- References.- 2 Functions of Hormones at the Cellular Level of Organization.- 2.1 Introduction.- 2.2 Promotive and Inhibitory Classes of Plant Hormones.- 2.3 Modes of Hormone Interaction.- 2.3.1 Interaction and Independence in Hormone Action.- 2.3.2 Synergism and Antagonism in Hormone Action.- 2.3.2.1 Synergism.- 2.3.2.2 Antagonism.- 2.3.3 Hormone Effects on Endogenous Hormone Levels.- 2.3.3.1 Hormonal Modification of Endogenous Auxin.- 2.3.3.2 Hormonal Modification of Endogenous Gibberellin.- 2.3.3.3 Hormonal Modification of Endogenous Ethylene.- 2.3.3.4 Hormonal Modification of Endogenous Abscisic Acid.- 2.3.3.5 Hormonal Modification of Endogenous Cytokinin.- 2.3.3.6 Summary.- 2.3.4 Influence of Environmental Parameters on Endogenous Hormones.- 2.3.4.1 Light.- 2.3.4.2 Water Stress.- 2.3.4.3 Temperature.- 2.3.4.4 Mechanical Stimulation.- 2.3.4.5 Summary.- 2.4 Hormonal Regulation.- 2.4.1 The Cell Cycle.- 2.4.1.1 Effect of Cytokinins.- 2.4.1.2 Effect of Auxins.- 2.4.1.3 Effects of Other Growth Regulators.- 2.4.2 Endomitosis.- 2.4.3 Meiosis.- 2.4.4 Summary.- 2.5 Hormone Effects on the Plane of Cell Division.- 2.6 Relationship of Cell Multiplication to Cell Expansion.- 2.7 Hormonal Regulation of Cell Expansion.- 2.7.1 Stem Cells.- 2.7.1.1 Effects of Auxin.- 2.7.1.2 Effects of Gibberellin.- 2.7.1.3 Effects of Cytokinin, Ethylene, and Abscisic Acid.- 2.7.2 Root Cells.- 2.7.2.1 Effects of Auxin.- 2.7.2.2 Effects of Gibberellin.- 2.7.2.3 Effects of Ethylene.- 2.7.2.4 Effects of Abscisic Acid.- 2.7.2.5 Effects of Cytokinin.- 2.7.3 Leaf Cells.- 2.7.3.1 Effects of Auxin.- 2.7.3.2 Effects of Gibberellin.- 2.7.3.3 Effects of Ethylene.- 2.7.3.4 Effects of Abscisic Acid.- 2.7.3.5 Effects of Cytokinin.- 2.7.4 Other Cell Types.- 2.7.4.1 Pollen Tubes.- 2.7.4.2 Epidermal Hairs.- 2.7.5 Lower Plants.- 2.7.5.1 Algae.- 2.7.5.2 Fungi.- 2.7.6 Summary.- References.- 3 Transport and Other Modes of Movement of Hormones (Mainly Auxins).- 3.1 Introduction.- 3.2 Historical Sketch.- 3.2.1 Indirect Evidence for Hormone Translocation.- 3.2.2 Direct Evidence for Hormone Translocation.- 3.2.3 Hormone Transport Experiments.- 3.2.3.1 The Early Period.- 3.2.3.2 The Period of Confirmation, Extension, and Criticism.- 3.2.3.3 The “Modern” Period.- 3.3 General Remarks on Hormone Movement.- 3.3.1 Terminology and the Transport Equation.- 3.3.2 Methods to Estimate Hormone Translocation Characteristics.- 3.3.2.1 Intercept Method of van der Weij.- 3.3.2.2 Short-Term Collecting Method.- 3.3.2.3 Pulse Experiments.- 3.3.2.4 Penetration-Depletion Method.- 3.3.2.5 Electric Potential Wave Method.- 3.3.3 Evaluation of Estimation and Interpretation of Hormone Movement.- 3.3.3.1 Does Auxin Move in a Stream?.- 3.3.3.2 Loading of the Transport System.- 3.3.3.3 Validity of Velocity Estimations.- 3.3.3.4 Fluctuations of Transport Velocity.- 3.3.3.5 Flexibility of the Transport System.- 3.3.4 Models for Transport Mechanisms.- 3.3.4.1 Conveyor Belt Model.- 3.3.4.2 Electrical Polarity Hypothesis.- 3.3.4.3 Polar Secretion Theory.- 3.3.4.4 Theory of Chemiosmotic Polar Diffusion.- 3.3.5 Binding Sites.- 3.3.6 Pathways of Hormone Movement.- 3.3.6.1 Shoots.- 3.3.6.2 Roots.- 3.4 Evidence of Hormone Translocation.- 3.4.1 Hormone Movement in Vascular Systems.- 3.4.2 Hormone Translocation in Shoot Sections.- 3.4.2.1 Auxins.- 3.4.2.2 Hormones Other than Auxins.- 3.4.3 Hormone Translocation in Root Sections.- 3.4.3.1 Auxins.- 3.4.3.2 Hormones Other than Auxins.- References.- 4 Functions of Hormones at Tissue Level of Organization.- 4.1 Introduction.- 4.2 Role of Hormones in Differentiation of Vascular Tissues.- 4.2.1 Regeneration in Shoots.- 4.2.1.1 Xylem.- 4.2.1.2 Sieve-Tube Elements.- 4.2.1.3 Fibers.- 4.2.2 Differentiation During Normal Development in Shoots.- 4.2.2.1 Xylem.- 4.2.2.2 Sieve-Tube Elements.- 4.2.2.3 Fibers.- 4.2.2.4 Cambium.- 4.2.3 Control of Differentiation in Roots.- 4.2.4 Evidence of Differentiation from Tissue Cultures.- 4.3 General Discussion.- References.- 5 Functions of Hormones at the Organ Level of Organization.- 5.1 Introduction.- 5.2 Embryogeny― Establishment of Polarity.- 5.3 Hormonal Relations of the Developing Embryo.- 5.4 Vascular Development―Spatial Arrangement.- 5.5 Regeneration.- 5.6 Flower Initiation.- 5.7 Flower Development.- 5.8 Fruit Setting and Development.- 5.9 Seed Development.- 5.10 Seed Dormancy―Germination Inhibitors.- 5.11 Conclusions.- References.- 6 Functions of Hormones at the Whole Plant Level of Organization.- 6.1 Introduction.- 6.2 Some Perspectives on the Nature of Hormones.- 6.3 A General View of the Role of Hormones in the Whole Plant.- 6.4 Some Considerations Regarding Experimental Design.- 6.5 Some Considerations Regarding Research Strategies.- 6.6 Conclusion.- References.- 7 Auxin Waves and Plant Morphogenesis.- 7.1 Introduction.- 7.2 Polar Transport of Auxin and Positional Information.- 7.3 The Origin of a New Concept.- 7.4 Some Experimental Evidence.- 7.5 The Proposed Model.- 7.6 Further Implications.- References.- Author Index.