Hormonal Regulation of Development III

R. P. PHARIS and D. M. REID The idea of a separate Encydopedia volume dealing with the "interrelations of plant hormones with factors in the environment of the plant, and its organs and tissues" originated with N. P. KEFFORD, and we are most appreciative of the help and advice provided by Prof. KEFFORD in the formative stages of this volume. We have thus interpreted "environment" very broadly to indude not only factors external to the plant, e. g. , gravity, light, temperature, wind, mechanieal wounding, water, organism s (induding pollen), and magnetic and electric stimuli, but internaI factors as well (e. g. , nutrients, both inorganic and photoassimilate, direction, and time). In our definition of "hormonaI effect", or "hormonaI involvement", we have asked our authors to take a broad ap­ proach, and to examine not only phenomena that are mediated by the known plant hormones, but to discuss as well a wide variety of processes and events where hormonal involvement is implied through more indirect analyses and observations. The volume begins with environmental factors internaI to the plant; R. J. WEAVER and J. O. JOHNSON thus examine "hormones and nutrients", their inter­ relationship in movement, accumulation, and diversion. As one studies a plant during its rapid growth phase, and later as maturation and aging proceed, it becomes apparent that time is an environmental cue of great significance, one which may exert a major influence via hormonal messages.

I: Factors Internal to the Plant.- Nutrients.- 1 Relation of Hormones to Nutrient Mobilization and the Internal Environment of the Plant: The Supply of Mineral Nutrients and Photosynthate.- 1 Introduction.- 2 Sources, Sinks, and Assimilate Movement in Relation to Morphology.- 2.1 Definitions of Source and Sink.- 2.2 Position Centers of Assimilate Production.- 2.3 Strength of the Sinks.- 2.4 Patterns of Distribution of Assimilates in Relation to Vascular Connections.- 2.5 The Demand for Assimilates.- 3 Role of Hormones and Growth Regulators in Assimilate Movement.- 3.1 Effect of Plant Hormones on Partition of Assimilates.- 3.2 Partition Between Roots and Shoots.- 3.3 Assimilate Partition Within the Shoot System.- 3.4 Mobilization of Assimilates into Fruits.- 3.5 Import of Assimilates into Expanded Leaves.- 3.6 Export of Assimilates When Leaves or Shoots Are Pretreated with Growth Substances.- 3.7 Time-Course Studies on Hormone-Induced Movement of 14C Assimilates.- 3.8 Effect of Hormone Concentration of Translocation.- 3.9 Interaction of Different Hormones on Hormone-Directed Transport.- 3.10 Effect of Water Relations on Auxin-Induced Mobilization.- 3.11 Roots as a Sink.- 3.12 Auxin and Senescence.- 3.13 Effect of Hormones on Mineral Nutrient Uptake.- 4 Possible Regulatory Points for Hormone-Directed Transport.- 4.1 Hormonal Regulation of Assimilate Movement at the Level of Source-Path-Sink.- 4.1.1 Time Between Treatments and Response.- 4.1.2 Effects on Nonelongating Tissues.- 4.1.3 Relationship Between the Lag Period and the Distance Moved by the Hormone.- 4.1.4 Polar Auxin Transport-Inhibitor Studies.- 4.1.5 Inhibitor Studies of Protein Synthesis and Nucleic Acid Metabolism (NAM).- 4.1.6 Metabolism and Accumulation Studies.- 4.1.7 Long-Distance Transport.- 4.1.8 Distinguishing Between Hormonal Effects on Sink Strength and Phloem Transport Processes.- 4.1.9 Rates of Photosynthesis, Export Rates of Assimilates and Changes in the Mobilizing Abilities Between Competing Sinks.- 5 Hormonal Regulation of Photosynthate Supply.- 6 Conclusions.- References.- Time-Related Factors and Phenomena.- 2 Rhythms and Their Relations to Hormones.- 1 Introduction.- 1.1 General.- 1.2 Plant Development.- 2 Bioperiodicities.- 2.1 Rhythm Characteristics.- 2.2 Ultradian Rhythms.- 2.3 Circadian Rhythms.- 2.4 Infradian Rhythms.- 2.5 Rhythm Interrelationships.- 3 Photoperiodism.- 4 Rhythms: Endogenous Hormones.- 5 Rhythms: Exogenous Growth Regulators.- 5.1 Auxins.- 5.1.1 Auxin Transport.- 5.1.2 Tropisms.- 5.1.3 Leaf Movements.- 5.2 Abscisic Acid, Cytokinins, Ethylene, and Gibberellins.- 5.3 Herbicides.- 6 Mechanisms.- 6.1 Chemical Oscillations.- 6.2 Transport.- 6.3 Enzymes.- 6.4 Ions and Membranes.- 7 Role of Rhythms in the Life of the Plant.- 7.1 Avoidance of Pathological Effects.- 7.2 Adaptive Significance.- 7.3 Organization in Time.- 8 Conclusions.- References.- Addendum: Turgorins.- 3 Hormonal Aspects of Phase Change and Precocious Flowering.- 1 Introduction.- 2 Factors Affecting Characteristics Associated with Juvenility.- 2.1 Inability to Flower.- 2.2 Ability to Initiate Adventitious Roots.- 2.3 Other Manifestations of Phase Change.- 3 Compositional Differences Between Juvenile and Adult Phases.- 3.1 Nucleic Acids.- 3.2 Proteins.- 3.3 Rooting Cofactors.- 3.4 Gibberellins.- 3.5 AbscisicAcid.- 3.6 Cytokinins.- 3.7 Sterols.- 4 Juvenile to Adult Phase Change and Its Reversibility.- 4.1 Influence of Cultural Techniques on Maturation.- 4.2 Reversions in Various Characteristics from Mature to Juvenile Phase.- 5 Tissue and Organ Culture of Juvenile and Adult Phases.- 6 Effect of Genotype on Length of the Juvenile Period.- 7 Summary and Conclusions.- References.- Direction.- 4 Polarity.- 1 Introduction.- 2 Single-Cell Systems.- 2.1 Fucoid Cells.- 2.2 Ochromonas.- 2.3 Single Cell Systems of Higher Plants.- 3 Muliple Cell Systems.- 3.1 Dictyostelium.- 3.2 Higher Plant Systems.- 3.2.1 Embryogenesis in Seed Plants.- 3.2.2 Growth, Development and Regeneration in Higher Plants.- 4 Models for Polarity.- 5 Conclusions.- References.- 5 Epinasty, Hyponasty, and Related Topics.- 1 Introduction.- 2 Epinasty in Response to Chemical Application.- 2.1 Ethylene and Ethrel.- 2.1.1 Leaves and Leaf Petioles.- 2.1.2 Stems.- 2.2 Auxins and Herbicides.- 2.2.1 Leaves.- 2.2.2 Stems.- 2.3 Gibberellins.- 2.4 Miscellaneous Chemicals.- 2.4.1 Brassins.- 2.4.2 Halogenated Phenolics.- 2.4.3 Morphactins and Malformin.- 3 Epinastic and Hyponastic Responses to Parasitic Microorganisms.- 4 Epinasty Induced by Physical Factors.- 4.1 Light.- 4.1.1 Wavelength.- 4.1.2 Intensity.- 4.2 Gravity.- 4.3 Waterlogging.- 5 Hormonal Theories.- 5.1 Laterial Shoots and Leaf Petioles.- 5.1.1 Auxin Direction.- 5.1.2 Differential Sensitivity.- 5.2 Plumular Hook Formation.- 5.3 Hyponasty.- 6 Concluding Remarks.- References.- 6 Position as a Factor in Growth and Development Effects.- 1 Introduction.- 2 The Nature of the Positional Signal.- 2.1 Compartmentation and the Availability of Growth Substrates.- 2.2 Some Salient Observations and Experiments on the Control of Cambial Growth.- 2.2.1 Growth in Relation to Position on the Bole.- 2.2.2 Growth of the Basal Taper and Buttresses of Tree Trunks.- 2.2.3 Inhibition of Cambial Growth.- 2.2.4 Growth Effects of Ringing or Girdling.- 2.2.5 A Possible Mechanism for Girdling Effects and Implications for the Positional Signal.- 3 Regulation of Sinks and Competition by the Positional Signal.- 3.1 Dependent or Induced Sinks.- 3.2 Autonomous or Uninduced Sinks.- 3.3 Competition Between Dependent and Autonomous Sinks.- 3.4 The Role of Ethylene.- 4 Propagation of the Positional Signal.- 4.1 The Descending Component.- 4.1.1 Sources of Positional Hormones in the Tops of Plants.- 4.1.2 Contribution of the Phloem.- 4.2 The Ascending Component.- 4.2.1 Roots as a Source of Hormones.- 4.2.2 Contribution of the Xylem.- 5 Conclusion.- References.- II: Factors External to the Plant Gravity.- Gravity.- 7 Roles of Hormones, Protons and Calcium in Geotropism.- 1 Introduction.- 2 Patterns of Response.- 2.1 Relevance of Kinetic Data.- 2.2 Difficulties of Temporally Separating Sequelae.- 2.3 Distribution of Receptivity.- 2.4 Patterns of Differential Growth.- 3 Hormonal Participation.- 3.1 Generalities About Roots and Shoots.- 3.2 Shoots.- 3.2.1 Perspective.- 3.2.2 Auxin.- 3.2.2.1 Establishing the Occurrence of Lateral Transport.- 3.2.2.2 The Time-Course of Lateral Transport.- 3.2.2.3 The Time-Course of Auxin-Induced Growth.- 3.2.2.4 Mature Shoots of Grass.- 3.2.2.5 Plagiogeotropism.- 3.2.3 Proton Secretion andVoltage Gradients.- 3.2.3.1 Perspective.- 3.2.3.2 Proton Asymmetry.- 3.2.3.3 Electrical Asymmetry.- 3.2.4 Gibberellins.- 3.2.4.1 Young, Orthogenotropic Shoots.- 3.2.4.2 Mature Shoots of Grass.- 3.2.4.3 Plagiogeotropic Systems.- 3.2.4.4 Overview.- 3.2.5 AbscisicAcid.- 3.2.6 Ethylene.- 3.2.6.1 Roles in Primary Curvature.- 3.2.6.2 Counter-Reactive Role.- 3.2.6.3 The Rationale for Counter-Reaction.- 3.2.6.4 Plagiogeotropism.- 3.2.7 Calcium (and Potassium and Phosphate).- 3.2.8 A Preliminary Model for the Roles of Calcium in Response to Gravity, Friction and Flexure.- 3.2.8.1 Current Concepts in Calcium Physiology.- 3.2.8.2 Reception.- 3.2.8.3 Activation of an Auxin Carrier.- 3.2.8.4 Electrochemical Migration of Calcium Across the Organ.- 3.2.8.5 The Vacuole as a Source of Cytosilic and Apoplastic Calcium.- 3.2.8.6 The Early Phase of Curvature.- 3.2.8.7 A Counter-Reaction.- 3.2.8.8 Membrane Deformation Resulting from Friction and Flexure.- 3.2.8.9 Crosstalk Between Geotropism and Response to Friction and Flexure.- 3.2.8.10 Auxin Regulation of Ethylene Synthesis via Cytosolic Calcium.- 3.2.8.11 Another Counter-Reaction.- 3.2.8.12 Alternative Models.- 3.2.9 More Factors and Asymmetries.- 3.2.9.1 Chemical Substances.- 3.2.9.2 Phloem Translocation.- 3.2.9.3 Transpiration.- 3.2.10 Differential Growth, and Recent Cavils About Its Control by Hormones.- 3.3 Roots.- 3.3.1 Perspective.- 3.3.2 Calcium in the Cap.- 3.3.3 Auxin.- 3.3.4 Connection Between Calcium in the Tip and Development of IAA Asymmetry.- 3.3.5 Ethylene.- 3.3.6 Protons.- 3.3.7 Secondary Asymmetries: Reaction and Counter-Reaction.- 3.3.7.1 Calcium in the Elongation Zone.- 3.3.7.2 Gibberellin and Other Hormones.- 3.3.7.3 “Adaptation”.- 3.3.8 Light, Inhibitors, and the Effect of Light on Inhibitors.- 3.3.9 Summary.- 4 Concluding Remarks.- References.- Light.- 8 De-Etiolation and Plant Hormones.- 1 Introduction.- 2 Auxins.- 2.1 Light and Auxin Transport.- 2.2 Light and Auxin Metabolism.- 3 Gibberellins.- 3.1 Cereal Leaf Growth.- 3.2 Photocontrol of Stem Extension.- 4 Ethylene.- 5 Cytokinins.- 6 Abscisic Acid and Other Inhibitors.- 7 Concluding Remarks.- References.- 9 Photoperiod and Hormones.- 1 General Concepts of Photoperiodism.- 1.1 Range of Responses.- 1.2 The Role of Leaves.- 1.3 Photoperception and the Photoperiodic Mechanism.- 1.3.1 Long-Night Processes.- 1.3.2 Long-Day Processes.- 2 Vegetative Growth: Stem Elongation.- 2.1 Rosette Plants.- 2.1.1 Gibberellins.- 2.1.2 Inhibitors.- 2.2 Caulescent Plants.- 3 Dormancy Phenomena.- 3.1 Storage Organs.- 3.1.1 Cytokinins.- 3.1.2 Inhibitors.- 3.1.3 Gibberellins.- 3.1.4 Auxins.- 3.1.5 Ethylene.- 3.1.6 Steroids.- 3.1.7 Conclusions.- 3.2 Resting Buds.- 3.2.1 Growth Inhibitors.- 3.2.2 Gibberellins.- 3.2.3 Cytokinins.- 4 Reproductive Behavior.- 4.1 Initiation of Floral Primordia.- 4.1.1 Florigen.- 4.1.2 Flower-Inhibiting Substances.- 4.1.3 Gibberellins.- 4.1.4 Abscisic Acid and Xanthoxin.- 4.1.5 Cytokinins.- 4.1.6 Auxin and Ethylene.- 4.1.7 Steroids.- 4.1.8 Conclusions.- References.- 10 Roles of Hormones in Phototropism.- 1 Introduction.- 2 Phototropic Phenomena.- 2.1 Overview: Dark-Grown Seedlings.- 2.2 Overview: Green Shoots.- 2.3 A Relatively Thorough Dose-Response Study.- 2.3.1 General Aspects.- 2.3.2 Regions of the Dose-Response Domain.- 2.3.3 A Unified View.- 2.3.4 Some Unexplained Problems.- 3 Hormonal Basis of Phototropism.- 3.1 Auxin.- 3.1.1 Dark-Grown Seedlings.- 3.1.2 Light-Grown Dicots.- 3.1.2.1 Auxin in the Stem.- 3.1.2.2 Auxin from Leaves.- 3.1.3 Mechanism of Auxin Transport.- 3.1.3.1 Basipetal Transport.- 3.1.3.2 Two Proposals for the Origin of Lateral Asymmetry.- 3.1.3.3 Experiments on Net Basipetal Transport.- 3.2 Gibberellins.- 3.3 Calcium and Other Agents and Effects.- 3.4 Conclusion.- References.- Temperature.- 11 Plant Growth Regulators and Low Temperature Stress.- 1.Introduction.- 2.Freezing Stress - Background Information.- 3.Dormancy and Cold Acclimation.- 4.Interrelations of Hormones with Freezing Stress.- 4.1 Translocatable Factors in Cold Acclimation.- 4.2 Evidence that Translocatable Factors Are Hormones.- 4.3 Effects of Hormones on Cold Acclimation.- 4.4 Exogenous Application of Synthetic Growth Regulators that Affect Cold Hardiness.- 5 The Relationship Between Chilling and Growth Regulators.- 6 The Relationship Between Deacclimation and Growth Regulators.- 7 Summary.- References.- Wind and Other Mechanical Factors.- 12 Wind and Other Mechanical Effects in the Development and Behavior of Plants, with Special Emphasis on the Role of Hormones.- 1 Introduction.- 2 Thigmonasty.- 2.1 The Thigmonastic Leaves of the Sensitive Mimosa and the Venus’ Fly Trap.- 2.1.1 Sensitive Mimosa.- 2.1.2 Venus’Fly Trap.- 2.2 Thigmonastic Flower Parts.- 2.3 Aquatic Thigmonastic Plants.- 2.3.1 Aldrovanda.- 2.3.2 Nematode Trapping Fungi.- 2.4 Plant Tendrils.- 2.5 Sundew.- 3 Thigmotropism.- 3.1 Thigmotropic Roots and Shoots.- 3.2 Thigmotropic Stamens.- 3.3 Thigmotropism in Fungi.- 4 Thigmomorphogenesis.- 4.1 Thigmomorphogenesis in Fungi.- 4.2 Thigmomorphogenesis in Vascular Plants.- 4.2.1 The Ecological Significance of Thigmomorphogenesis.- 4.2.2 The Time Course of Thigmomorphogenesis.- 4.2.2.1 Histological Studies.- 4.2.3 Integrative Mechanisms in Thigmomorphogenesis.- 4.2.3.1 Action Potentials.- 4.2.3.2 The Role of Ethylene.- 4.2.3.3 The Role of Auxin.- 4.2.3.4 The Role of Translocation and Transpiration.- 4.2.4 Photosynthesis, Respiration, and Metabolism.- 4.2.5 Interaction of Mechanical Stimulation with Other Environmental Cues.- 5 Conclusions.- References.- 13 Hormonal Control of Wound-Induced Responses.- 1 Introduction.- 2 Formation of Protective Materials.- 2.1 Suberization or Cutin Formation at the Wound Surface.- 2.2 Lignification.- 3 Wound-Induced Cell Division and Its Hormonal Control.- 4 Organized Wound Response.- 4.1 Vascular Element Differentiation.- 4.2 Root Formation on Stem Cuttings.- 5 Biochemical Activation of Wound-Affected Cells.- 5.1 Factors Affecting Wound-Induced Metabolic Changes.- 5.2 Wound-Induced Change in Hormone Levels.- 6 Conclusion.- References.- 14 Water Relations and Plant Hormones.- 1 Introduction.- 2 Insufficient Water.- 2.1 Causes of Drought.- 2.2 Some Problems in Interpreting the Literature.- 2.3 Control Points for Water Loss and Gain.- 2.4 Sequence of Responses to Water Stress.- 2.4.1 The Initial Response.- 2.4.2 Later Responses.- 2.5 Drought Induced Changes in Levels of Hormone: Effects on Stomatal Functioning.- 2.5.1 Gibberellins and Stomates.- 2.5.2 Auxins and Stomates.- 2.5.3 Ethylene and Stomates.- 2.5.4 Cytokinins and Stomates.- 2.5.5 ABA and Stomatal Closure.- 2.5.6 ABA and Stomatal Opening.- 2.5.7 Summary of Section 2.5.- 2.6 Water Uptake and Movement Through Roots.- 2.6.1 Drought and Hormone Levels in Roots.- 2.6.2 Effects of Hormones and Nutrient Redistribution and ? of Roots.- 2.6.3 Effects of Hormones and Ion Transport.- 2.7 Other Mechanisms Controlling Water Status of the Plant.- 2.7.1 Reduced Growth Rate.- 2.7.2 Root Growth and Development.- 2.7.3 Leaf Morphology and Behavior.- 2.7.4 Flowering and Reproductive Development.- 2.7.5 Summary of Sections 2.7.1 to 2.7.4.- 2.7.6 Water Stress and CO2 Assimilation.- 2.7.7 Osmoregulation.- 3 Excess Water.- 3.1 Morphological Effect of Flooding.- 3.2 Causes of Flood-Induced Morphological Changes.- 3.3 Cytokinins.- 3.4 AbscisicAcid.- 3.5 Gibberellins.- 3.6 Auxins.- 3.7 Ethylene and Its Interaction with Auxins.- 3.8 Hormones and Photosynthate Transport and Partitioning.- 3.9 Summary of Section 3.- References.- Organisms.- 15 Pollen. Symbionts and Symbiont-Induced Structures.- 1 Pollen.- 1.1 Effect of Hormones on Pollen Germination and Tube Growth.- 1.2 Hormonal Composition of Pollen.- 1.3 Pollen, Hormones, and Fruit Set.- 2 Symbionts and Symbiont-Induced Structures.- 2.1 Nitrogen-Fixing Associations.- 2.1.1 Auxins.- 2.1.2 Gibberellins.- 2.1.3 Cytokinins.- 2.1.4 Interaction of Growth Substances in Nodule Development.- 2.2 Mycorrhizae.- References.- 16 Pathogenic and Non-pathogenic Microorganisms and Insects.- 1 Hormones and Microorganisms.- 1.1 Ethylene.- 1.1.1 Fungal Production of Ethylene.- 1.1.2 Bacterial Production of Ethylene.- 1.1.3 Biosynthesis of Ethylene.- 1.1.4 Ethylene and Plant Pathogenesis.- 1.2 Auxins.- 1.2.1 Fungal Production of Auxins.- 1.2.2 Effects of Auxins of Fungal Growth.- 1.2.3 Bacterial Production of Auxins.- 1.3 Cytokinins.- 1.3.1 Bacterial Production of Cytokinins.- 1.3.2 Fungal Production of Cytokinins.- 1.4 Gibberellins.- 1.4.1 Fungal Production of GA’s.- 1.4.2 Bacterial Production of GA’s.- 1.5 Phytotoxins Produced by Microorganisms with Growth Hormone Properties.- 2 Insects and Nematodes.- References.- 17 Electrical and Magnetic Stimul.- 1 Introduction.- 2 Electrical Stimuli.- 2.1 Historical Background.- 2.2 Measurement Techniques.- 2.2.1 Biopotential Differences.- 2.2.2 Resistance.- 2.2.3 Current.- 2.2.4 Capacitance.- 2.2.5 Dielectric Constant.- 2.3 Seed or Tissue Viability.- 2.4 Photoelectric Responses.- 2.5 Geoelectric Responses.- 2.6 Hormone Transport.- 2.7 Growth-Regulating Compounds in Relation to the Membrane or Cell Walls.- 2.8 Alterations of Growth by Applied Electric Fields.- 2.9 Electrogenesis, Membranes, ATPases and Contractile Proteins.- 2.10 Hypothesis of Hormone-Electric Interaction.- 3 Magnetic Stimuli and Hormones.- 4 Conclusion.- References.- 18 Regulators of Plant Reproduction, Growth and Differentiation in the Environmen...