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.

Contenu

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 S…