Cellular Interactions

ISBN-13: 9783642693014 / Angielski / Miękka / 2011 / 743 str.

H. F. Linskens; J. Heslop-Harrison

Opis

H. F. LINSKENS and J. HESLOP-HARRISON The chapters of this volume deal with intercellular interaction phenomena in plants. Collectively they provide a broad conspectus of a highly active, if greatly fragmented, research field. Certain limitations have been imposed on the subject matter, the most impor tant being the exclusion of long-range interactions within the plant body. It is true that pervasive hormonal control systems cannot readily be demarcated from controls mediated by pheromones or information-carrying molecules with more limited spheres of action, but consideration is given in this volume to the main classes of plant hormones and their functions only incidentally, since these are treated adequately in other volumes of this Encyclopedia series (V - ume 9-11) and in numerous other texts and reviews. Similarly, certain other effects, such as those associated with nutrients and ions, are not considered in any detail. Furthermore, we have excluded intracellular interactions, and also consideration of transport phenomena, which are treated in detail in Vol ume 3 of this Series. Other aspects of inter-cellular interaction, such as cell surface phenomena and implications of lectin-carbohydrate interactions, and plant-virus inter-relationships, are treated in other sections of this Encyclopedia (Volumes 13B and 14B, respectively). In the volume on physiological plant pathology (Volume 4 of this series) special attention has been given to host pathogen interaction. These aspects of our subject will therefore be excluded in the present treatise."

Spis treści

1 Introduction.- 2 Cellular Interaction: a Brief Conspectus.- 2.1 Introduction.- 2.2 The Cell Surface.- 2.3 The Plant Cell Wall.- 2.4 Cell-Cell Communication: Plant and Animal Situations Compared...- 2.5 Specific Interactions: Models and Theories.- 2.6 Self and Non-Self.- 2.7 Secondary Responses.- 2.8 Types of Cellular Interaction in Plants.- References.- 3 Evolutionary Aspects of the Eukaryotic Cell and Its Organelles.- 3.1 Introduction.- 3.1.1 The Origin of the Eukaryotic Cell.- 3.1.2 The Acquisition of Eukaryotic Features.- 3.1.3 The Origin of Eukaryotic Organelles.- 3.2 Group 1: Endomembrane Organelles.- 3.2.1 The Endomembrane System.- 3.2.2 Dictyosomes.- 3.2.3 Microbodies.- 3.2.4 Vacuoles and Lysosomes.- 3.2.5 Ejectile Organelles.- 3.3 Group 2: Mitochondria and Chloroplasts.- 3.3.1 The Endosymbiotic Hypothesis.- 3.3.2 Mitochondria - Their Possible Ancestry.- 3.3.3 Modification Within the Protoeukaryotic Host.- 3.3.4 Chloroplasts.- 3.4 Other Organelles.- 3.4.1 The Nucleus.- 3.4.2 Hypotheses on the Origin of the Nucleus.- 3.4.3 Microtubules.- 3.4.4 Speculations and Sequences of Origin.- 3.5 Metabolic Interactions.- 3.5.1 Fermentations and Oxygen.- 3.5.2 Aerobic Organisms, Endosymbiosis and the Integration of Metabolism.- 3.5.3 Protein Synthesis and Nuclear Control.- 3.5.4 Chloroplast Metabolism.- 3.5.5 Photorespiration: Three Cooperating Organelles.- 3.6 Concluding Remarks.- References.- 4 Autotrophic Eukaryotic Freshwater Symbionts.- 4.1 Introduction.- 4.2 The Taxonomic Position of Symbiotic Partners.- 4.3 The Location of Autotrophic Partners.- 4.4 Physiological Features of Symbiotic Partners and Their Association...- 4.5 Self-Regulation and Partner-Coordination in Endosymbiotic Systems.- 4.6 Specifity of Cell Recognition and Symbiotic Partnership.- 4.7 Ecology of Endosymbiotic Systems.- References.- 5 Autotrophic Eukaryotic Marine Symbionts.- 5.1 Introduction.- 5.2 Symbiont Genera and Species.- 5.2.1 RANGE.- 5.2.2 Systematics.- 5.3 Cellular Relationships of Symbionts and Hosts.- 5.3.1 Recognition and Selection.- 5.3.2 Placement.- 5.3.3 Regulation.- 5.4 Primary Production.- 5.4.1 Photosynthesis.- 5.4.2 Endosymbiotic Exchange of Carbon and Nitrogen.- 5.5 Ecology.- 5.6 Conclusions.- 5.7 Addendum - Prochloron (by R.A. Lewin).- References.- 6 Endosymbiotic Cyanobacteria and Cyanellae.- 6.1 Introduction.- 6.2 Taxonomy and Localization.- 6.2.1 Multicellular Hosts.- 6.2.1.1 Bryophytes.- 6.2.1.2 Pteridophytes.- 6.2.1.3 Gymnosperms.- 6.2.1.4 Angiosperms.- 6.2.1.5 Sponges.- 6.2.1.6 Tunicates.- 6.2.1.7 Others.- 6.2.2 Unicellular Hosts.- 6.2.2.1 Geosiphon pyriforme.- 6.2.2.2 Amoebae and Apoplastidal Algae.- 6.2.2.3 Diatoms.- 6.2.2.4 Cyanidium caldarium.- 6.3 Physiology.- 6.3.1 Nitrogen Metabolism.- 6.3.2 Carbon Metabolism.- 6.4 Symbiosis-Specific Features.- 6.4.1 Morphology.- 6.4.2 Physiology, Behavioural and Ecological Features.- 6.4.3 Regulation and Host-Symbiont Specificity.- 6.5 Conclusions.- References.- 7 Epiphytism at the Cellular Level with Special Reference to Algal Epiphytes.- 7.1 Introduction.- 7.2 Dispersal and Contact of Algal Epiphytes.- 7.2.1 Vegetative Propagules.- 7.2.2 Thallus Fragmentation as Dispersal Mechanisms.- 7.2.3 Spores.- 7.3 Specificity of Epiphytic Relationship.- 7.3.1 Specificity of Brown Algal Epiphytes and Basiphytes.- 7.3.2 Specificity of Red Algal Epiphytes on Brown Algal Basiphytes.- 7.3.3 Specificity of Red Algae as Epiphytes and Basiphytes.- 7.3.4 Seagrasses and Algal Epiphytes.- 7.3.4.1 Non-Specific Epiphytes.- 7.3.4.2 Specific Epiphytes.- 7.4 Ion Exchange and Nutrient Transfer Between Basiphyte and Epiphyte.- 7.4.1 Experimental Translocation of Radioactive Compounds.- 7.4.1.1 Algae as Epiphytes and Basiphytes.- 7.4.1.2 The Special Case of Ascophyllum nodosum and Polysiphonia lanosa.- 7.4.1.3 Algae Epiphytic on Seagrasses.- 7.4.1.4 Effect of Epiphytes on Eelgrass Photosynthesis.- 7.4.2 Implications of Seasonality of Epiphytes.- 7.5 Defence of Basiphytes Against Epiphytes.- 7.5.1 Self-Cleaning Process of Actively Growing Basiphytes.- 7.5.2 Production of Antibiotics by Basiphytes.- 7.6 Conclusions.- References.- 8 Genetics of Recognition Systems in Host-Parasite Interactions.- 8.1 Introduction.- 8.2 Gene-for-Gene Hypothesis.- 8.3 Genetic Fine Structure.- 8.3.1 Rust Resistance in Flax.- 8.3.2 The Rust Melampsora lini.- 8.3.2.1 Sexuality.- 8.3.2.2 Genetics of Virulence.- 8.4 Mutation Studies.- 8.4.1 Host Plants.- 8.4.2 Mutation in Pathogens.- 8.5 The Recognition Mechanism.- 8.5.1 Models Involving Phytoalexin Synthesis.- 8.5.2 Models and Their Implications.- 8.5.3 Some Simpler Bacterial Systems.- 8.5.4 Application of Molecular Genetics to Fungal Systems.- 8.6 Non-Host Resistance.- References.- 9 The Mycorrhizal Associations.- 9.1 Introduction.- 9.2 Initiation of Infection.- 9.3 Structure and Development of Myorrhizal Roots.- 9.4 Fine Structural Relationship Between the Symbionts.- 9.5 Specificity in Mycorrhizal Symbiosis.- 9.6 Effectiveness of Mycorrhizal Infection.- 9.7 Compatibility and Effectiveness.- 9.8 Recognition.- 9.9 Ecological Aspects of Mycorrhizal Infection.- References.- 10 Plant-Bacterial Interactions.- 10.1 Introduction.- 10.2 Incompatible Interactions.- 10.2.1 Characteristics of the Hypersensitive Reaction.- 10.2.2 Factors that Affect Expression of the Hypersensitive Response.- 10.2.3 Attachment of Bacteria to Plant Cell Walls: A Requirement for Induction of the HR?.- 10.2.4 Cell-Wall Components Involved in Attachment.- 10.3 Compatible Interactions.- 10.3.1 The Agrobacterium tumefaciens-Plant Interaction.- 10.3.2 The Rhizobium-Legume Interaction.- 10.3 2.1 Attachment of Rhizobia to Plant Cell Walls.- 10.3 2.2 The Role of Extracellular Polysaccharides in Specificity of Rhizobia.- 10.3 2.3 The Role of Lipopolysaccharides in Specificity of Rhizobia.- 10.3 2.4 The Lectin Receptor Hypothesis.- 10.4 Concluding Remarks - The Potential for Manipulating Plant-Bacterial Interactions.- References.- 11 Cellular and Molecular Recognition Between Higher Plants and Fungal Pathogens.- 11.1 Introduction.- 11.2 Recognition of the Host by the Parasite.- 11.2.1 Spore Germination.- 11.2.2 Chemotaxis and Recognition.- 11.2.3 Zoospore Binding to Root Surfaces.- 11.2.4 Recognition and Tropisms.- 11.3 Recognition of the Pathogen by the Host: Resistance Triggering.- 11.3.1 The Genetic Argument.- 11.3.2 Evolution of Resistance and Its Implications for Recognition.- 11.3.3 Pathogen Cognons as Modulators of Host Defence.- 11.3.3.1 Polysaccharide Elicitors.- 11.3.3.2 Protein and Glycoprotein Elicitors.- 11.3.3.3 Other Elicitors.- 11.3.3.4 Specificity Factors.- 11.3.4 Recognition of Pathogen Cognons and Their Modes of Action.- 11.3.5 Conclusions: Models for Specific Recognition.- References.- 12 Mating Systems in Unicellular Algae.- 12.1 Introduction.- 12.2 Cellular Interactions Effecting Gametic Differentiation Erogens. Contact-Induced Gametogenesis.- 12.2.1 Erogens.- 12.2.2 Contact-Induced Gametogenesis.- 12.3 Chemotaxis. Erotactins (Sirenins). Chemotropism. Chemotropins.- 12.4 Sex Cell Contact.- 12.4.1 The Mating Type Reaction and Its Molecular Basis.- 12.4.1.1 The Isoagglutinins (IA’s).- 12.4.1.2 The Mating Type Substances.- 12.5 Inactivation of Agglutinins During Gamete Contact.- 12.6 Correlations Between Mating Type Reaction and Pairing.- 12.7 Termination of the Mating Type Reaction by Pairing.- 12.8 Sexual Incompatibility Between Species Resulting from Taxon-Specific or Defective Intercellular Communication and Contact Systems.- References.- 13 Colony Formation in Algae.- 13.1 Introduction.- 13.2 Non-Coenobic Colonies.- 13.3 Coenobic Colonies.- 13.3.1 Motile Coenobic Colonies.- 13.3.1.1 Family Volvocaceae.- 13.3.1.2 Family Astrephomenaceae.- 13.3.1.3 Family Spondylomoraceae.- 13.3.1.4 Family Haematococcaceae.- 13.3.2 Non-Motile Coenobic Colonies.- 13.3.2.1 Reproduction by Non-Motile Spores.- 13.3.2.2 Reproduction by Motile Spores.- 13.4 Summary.- References.- 14 Cellular Interaction in Plasmodial Slime Moulds.- 14.1 Introduction.- 14.2 Fusion Between Amoebae.- 14.2.1 Physarum polycephalum.- 14.2.2 Didymium iridis.- 14.2.3 Conclusions Concerning Interactions Between Amoebae of Myxomycetes.- 14.3 Somatic Incompatibility Between Plasmodia.- 14.3.1 Physarum polycephalum.- 14.3.2 Didymium iridis.- 14.3.3 Conclusions Concerning Somatic Incompatibility.- References.- 15 Cell Interactions in the Cellular Slime Moulds.- 15.1 Introduction.- 15.2 Spore Germination.- 15.3 Growth Phase.- 15.4 Social Phase.- 15.5 Pattern Formation.- 15.6 Culmination.- 15.7 Acrasins.- 15.8 Signal-Receptor Interaction.- 15.9 Cyclic GMP as Mediator.- 15.10 Conclusions.- References.- 16 Sexual Interactions in the Lower Filamentous Fungi.- 16.1 Introduction.- 16.2 Chytridiomycetes.- 16.3 Oomycetes.- 16.4 Zygomycetes.- 16.5 Concluding Remarks.- References.- 17 Barrage Formation in Fungi.- 17.1 Introduction.- 17.2 Intraspecific Barrages.- 17.2.1 Barrages Associated with Homogenic Incompatibility.- 17.2.2 Barrages Associated with Heterogenic Incompatibility.- 17.2.2.1 Podospora anserina.- 17.2.2.2 Wood-Destroying Basidiomycetes.- 17.2.2.3 Comparable Phenomena in Other Fungi.- 17.3 Interspecific Barrages.- 17.4 Intergeneric Barrages.- 17.5 Biological Significance of Barrage Formation.- References.- 18 Physiological Interactions Between the Partners of the Lichen Symbiosis.- 18.1 Introduction.- 18.1.1 The Lichen Components.- 18.1.1.1 The Algal Partner.- 18.1.1.2 The Fungal Partner.- 18.1.2 The Lichen Thallus.- 18.1.2.1 Fungus-Alga Relation.- 18.2 Alga-Fungus Interactions.- 18.2.1 Carbohydrate Metabolism.- 18.2.1.1 Carbohydrate Efflux.- 18.2.1.2 Transfer of Carbohydrates.- 18.2.1.3 Uptake and Conversion of Transferred Carbohydrate by the Mycobiont.- 18.2.2 Nitrogen Metabolism.- 18.2.2.1 Nitrogen and Amino Acid Analysis of Whole Thalli.- 18.2.2.2 Nitrogen Fixation.- 18.3 Other Effects of Symbiosis.- 18.3.1 Effects of Symbiosis on the Algal Partner.- 18.3.1.1 Cyanobacterial Phycobionts.- 18.3.1.2 Eukaryotic Phycobionts.- 18.3.1.3 Cell-Wall Modifications.- 18.3.2 Effect of Symbiosis on the Fungal Partner.- 18.3.2.1 Concentric Bodies.- 18.3.2.2 Secondary Metabolic Products “Lichen Substances”.- 18.3.2.3 The Cell Wall of the Mycobionts.- 18.4 Interactions Between Lichen Symbionts.- 18.4.1 Selectivity and Recognition: General Considerations.- 18.4.2 Selectivity in Lichens.- 18.4.2.1 Identification of Phycobionts.- 18.4.2.2 Resynthesis in Vitro.- 18.4.2.3 Selectivity at the Contact Phase.- 18.4.2.4 Resynthesis in Situ.- 18.5 Concluding Remark.- References.- 19 Mating Systems and Sexual Interactions in Yeast.- 19.1 Introduction.- 19.2 Sexual Differentiation.- 19.2.1 Genetic Control.- 19.2.2 Molecular Basis.- 19.2.2.1 Agglutination Substances.- 19.2.2.2 Sex Pheromones.- 19.2.2.3 Binding Substances.- 19.3 Sexual Interactions.- 19.3.1 The Process of Mating Reaction.- 19.3.2 Control of Mating Processes.- 19.3.2.1 Control of Sexual Agglutinability.- 19.3.2.2 Mechanism of Agglutinability Induction.- 19.3.2.3 G1 Arrest Caused by Sex Pheromones.- 19.3.2.4 Biochemical Changes Caused by ?-Pheromones.- 19.3.3 Interspecific and Intergeneric Sexual Interactions.- 19.4 Conclusion.- References.- 20 Cellular Interactions During Early Differentiation.- 20.1 Introduction.- 20.2 Cell Cycle and Cell Differentiation.- 20.3 Re-Differentiation in Organ and Tissue Fragments.- 20.4 Differentiation in Embryos and Embryoids.- 20.4.1 Embryos.- 20.4.2 Embryoids.- 20.5 Differentiation Within and at the Border of Apical Meristems…..- 20.5.1 Root Apical Meristems.- 20.5.2 Shoot Apical Meristems.- 20.5.3 Meristems in Lower Plants.- 20.6 Onset of Vascular Differentiation.- 20.7 Concluding Remarks.- References.- 21 Cellular Recognition Systems in Grafting.- 21.1 Introduction.- 21.2 Inter-Relationships Between the Wound Reaction and Graft Formation.- 21.3 Evidence for Recognition from Investigations into Graft Compatibility and Graft Incompatibility.- 21.3.1 Incompatibility and Graft Rejection.- 21.3 2 How May Incompatibility Be Overcome?.- 21.4 Cellular Events at the Stock-Scion Interface.- 21.4.1 Initial Adhesion of Opposing Pith Cells.- 21.4.1.1 Specificity of Cellular Interactions.- 21.4.1.2 Nature and Mechanism of Secretion of the Adhesive.- 21.4.1.3 Significance of the Attainment of Vascular Continuity.- 21.4.2 Proliferation at the Graft Interface and the Establishment of Cellular Contact.- 21.4. 3 Erosion of the Middle Lamella.- 21.4. 4 Formation of Plasmodesmata.- 21.4. 5 Development of Interconnecting Pits and the Differentiation of Cell Units.- 21.5 Cellular and Molecular Basis of a Recognition System in Grafting.- 21.5.1 Location of the Sensing Mechanism.- 21.5.2 Nature of the Sensing Mechanism.- 21.5.3 A Tentative Model.- References.- 22 Cellular Polarity.- 22.1 Introduction.- 22.2 Rise of Cell Polarity in Single Plant Cells.- 22.2.1 Segregation and Redistribution of Cellular Components: Observations on the Fucus Zygote.- 22.2.2 Electrophysiology and Morphogenesis: Transcellular Electric Fields and Ionic Currents.- 22.3 Polarity Induction.- 22.3.1 Application of Ionic and Electrical Gradients.- 22.3.2 Cell Polarization by Light.- 22.3.3 Cell Polarization by Signal Molecules.- 22.4 Cellular Polarity in Higher Plants.- 22.5 Concluding Discussion.- References.- 23 Fusion of Somatic Cells.- 23.1 Introduction.- 23.2 Preparation of Protoplasts.- 23.2.1 Preparation from Tobacco Mesophyll.- 23.2.2 Preparation from Tissue Culture Cells.- 23.3 Methods of Protoplast Fusion.- 23.3.1 Spontaneous Fusion.- 23.3.2 Sodium Nitrate Method.- 23.3.3 High pH-High Ca2+ Method.- 23.3.4 Polyethylene Glycol Method.- 23.3.5 Polyvinyl Alcohol Method.- 23.3.6 Electrical Pulse Method.- 23.4 Mechanism of Protoplast Fusion.- 23.4.1 Surface Characteristics of Protoplasts.- 23.4.2 Adhesion of Protoplasts.- 23.4.2.1 High pH-High Ca2+ Method.- 23.4.2.2 Polyethylene Glycol Method.- 23.4.2.3 Electrically Induced Aggregation.- 23.4.2.4 Lectin-Induced Aggregation.- 23.4.3 Fusion of Protoplasts.- 23.4.3.1 High pH-High Ca2+ Method.- 23.4.3.2 Polyethylene Glycol Method.- 23.4.3.3 Electrical Pulse Method.- 23.5 Liposomes as Models of Cell Fusion.- 23.6 Conclusion.- References.- 24 Pollen - Pistil Interactions.- 24.1 Introduction.- 24.2 Cell Biology of Pollen - Pistil Interactions.- 24.2.1 The Pollen Grain.- 24.2.1.1 Pollen-Wall Structure and Compartments.- 24.2.1.2 The Pollen Tube.- 24.2.2 The Pistil.- 24.2.2.1 Types of Stigma.- 24.2.2.2 The Style-Pathway for Pollen Tube Growth.- 24.2.3 Mating Systems in Plants: An Evolutionary Perspective.- 24.2.4 Pollination Systems in Flowering Plants.- 24.2.4.1 Self-Incompatibility Systems.- 24.2.4.2 Dichogamy and Other Isolating Mechanisms.- 24.2.4.3 Compatible Systems.- 24.2.4.4 Pollination-Stimulated Ovule Differentiation.- 24.3 Physiology of Interacting Cells and Tissues.- 24.3.1 Physiological Characteristics of Pollen.- 24.3.2 Pollen Germination and Tube Growth.- 24.3.3 Stigma Physiology Before and After Germination of Pollen..- 24.4 Molecular Aspects of Pollen - Pistil Interactions.- 24.41 The Pollen Surface.- 24.4.1.1 Extracellular Pollen Proteins.- 24.4.2 The Stigma Surface and Style Mucilage.- 24.4.2.1 Composition.- 24.4.2.2 Function of Exudate.- 24.5 Control of Pollen - Pistil Interactions.- 24.5.1 Adhesion.- 24.5.2 Hydration.- 24.5.3 Models of Recognition and Receptors.- 24.5.4 Response.- 24.5.4.1 In-Vivo Responses.- 24.5.4.2 In-Vitro Responses.- 24.5.4.3 Evidence for Signalling.- 24.5.4.4 Pollen-Tube Growth and Gamete Competition.- 24.5.4.5 Co-Adaptations of Pollen, Stigma and Biotic Pollinators.- 24.6 Conclusions.- References.- 25 Mentor Effects in Pollen Interactions.- 25.1 Introduction.- 25.2 Survey of Cases Reported.- 25.3 Hypothesized Mechanisms for Mentor Effects.- 25.4 Overall Interpretation and Conclusion.- References.- 26 Incompatibility.- 26.1 Introduction, Definitions and General References.- 26.2 Self-Incompatibility.- 26.2.1 Classification of Self-Incompatibility Systems.- 26.2.1.1 Site of Formation of S-Gene Products in the Pistil.- 26.2.1.2 Site of Formation of S-Gene Products in the Stamen.- 26.2.1.3 Floral Polymorphism.- 26.2.2 Site of Inhibition.- 26.2.3 Genetic Control.- 26.2.4 Mutability and Structure of Self-Incompatibility Loci.- 26.2.4.1 Loss of Function in Pollen and Pistil.- 26.2.4.2 The Generation of New S-Alleles.- 26.2.5 Physiology and Biochemistry of Self-Incompatibility.- 26.2.6 Evolution and Distribution of Self-Incompatibility.- 26.3 Interspecific Incompatibility.- 26.3.1 Relationships to Self-Incompatibility.- 26.3.1.1 Morphological Similarities.- 26.3.1.2 The SI x SC Rule.- 26.3.1.3 The Dual Function of the Self-Incompatibility Locus.- 26.3.2 Incongruity.- 26.3.3 Distribution of Interspecific Incompatibility.- 26.3.4 Methods for Overcoming Interspecific Incompatibility.- References.- 27 Incongruity: Non-Functioning of Intercellular and Intracellular Partner Relationships Through Non-Matching Information.- 27.1 Introduction.- 27.2 Coevolution.- 27.3 Genetics of an Intimate Partner Relationship.- 27.4 Incongruity.- 27.5 Evolution of Incongruity.- 27.6 Genetics of Incongruity.- 27.7 Nature of Incongruity.- 27.8 Revision of Visions: Incongruity and Incompatibility.- 27.9 Incongruity and the Prospects of Gene Manipulation in Higher Plants.- 27.10 Exploitation of Incongruity.- 27.11 Related Fields of Research; with Special Reference to the Host-Parasite Relationship.- 27.12 Conclusions.- References.- 28 Allergic Interactions.- 28.1 Introduction.- 28.2 Allergic Responses Caused by Plants.- 28.2.1 Atopic Allergy.- 28.2.2 Delayed-Type Hypersensitivity.- 28.2.3 Other Factors Influencing Allergic Responses.- 28.3 Occurrence and Nature of Allergens.- 28.3.1 Atopic Allergens.- 28.3.2 Contact Allergens.- 28.3.2.1 Sesquiterpene Lactones.- 28.3.2.2 Catechols.- 28.3.2.3 Quinones.- 28.3.2.4 Other Contact Allergens.- 28.3.2.5 Mechanism of Allergenicity.- 28.3.3 Allergenic Cross-Reactivity.- 28.4 Sites of Allergens Within the Plant.- 28.5 Role of Allergens in Plants.- 28.5.1 Atopic Allergens.- 28.5.2 Contact Allergens.- 28.6 Conclusions.- References.- Author Index.- Index of Plant Genera.