Review.- Archaea (Archaebacteria).- 1. Introduction.- 2. First Recognition and Establishment of Archaebacteria as the Domain Archaea.- 3. Taxonomy and Ecology of Archaea.- 4. Characteristics of Archaea.- a) Morphology and Cytology.- b) Cell Walls and Cell Envelopes.- c) Metabolism.- ?) Central Metabolism.- ?) Chemolithoautotrophic Metabolism.- d) Lipids.- e) Modified Nucleosides in Transfer RNA.- f) DNA-Dependent RNA Polymerases.- g) ATP Synthetase (ATPase).- h) Genome Organization.- 5. Biotechnological Potential of Archaea.- a) Methanogens.- b) Halobacteria.- c) Thermoacidophilic Archaea.- d) Archaea as a Source of Thermophilic Enzymes.- 6. Archaea and the Origin of Life.- References.- A. Structural Botany.- I. Cytology and Morphogenesis of the Prokaryotic Cell.- 1. Eubacterial Cell Wall Structure and Assembly Processes.- a) Cell Wall Morphology and Assembly in Gram-Positive Bacteria.- b) Heteromorphism of Cell Envelope in Gram-Negative Bacteria.- c) Cell Wall Synthesis and Turnover in Gram-Negative Bacteria.- 2. Archebacterial Crystalline Surface Layers.- a) Structure and Assembly of a Coccoid Archebacterium.- b) Structural Aspects in a Filamentous Archebacterium.- 3. Periplasmic Space.- 4. New Features of the Flagellar Base.- 5. Cell-Cell Interactions in Myxobacteria.- References.- II. Cell Architecture and Cellular Morphogenesis of Eukaryotic Algae (Rhodophyta and Phaeophyta).- 1. Rhodophyta.- a) General Aspects of Cell Structure.- ?) Organellar Associations.- ?) Dictyosomes.- ?) Mitochondria.- ?) Endoplasmic Reticulum (ER).- ?) Rhodoplasts.- ?) Cell Walls.- ?) Pit Plugs.- b) Structure and Behavior of the Interphase Nucleus.- ?) Polygenomy.- ?) Nuclear Transfer and Cell Fusion.- ?) Filament Repair.- ?) Host-Parasite Interactions.- c) Cytoskeleton, Cell Division, and Mitosis.- d) Vegetative Morphogenesis.- ?) Cell Expansion.- ?) Side Branch Initiation.- ?) Protoplasts and Cell Culture.- e) Spermatangia and Spermatia.- f) Carpogone and Postfertilization Processes.- ?) Interaction of Spermatia with the Carpogone.- ?) Recognition Events Associated with Nuclear Transfer.- ?) Fine Structure of Carpogone and Carposporophyte.- g) Sporangia and Spores.- ?) Tetraspore Formation.- ?) Spore Germination.- 2. Phaeophyta.- a) Vegetative Cell Structure.- b) Mitosis, Cytokinesis, and the Cytoskeleton.- c) Cell Wall.- d) Motile Reproductive Cells.- e) Oogonia.- f) Fertilization and Early Postfertilization Processes.- g) Polyspermy Block.- h) Cell Polarity and Germination.- References.- III. Phloem Regeneration.- 1. Introduction.- 2. Phloem Regeneration After Wounding.- a) Tissue Changes Preceding Wound-Phloem Development.- b) Ultrastructure.- c) The Induction of Wound-Sieve Tubes and Their Contact to Bundle Phloem.- d) Translocation in Wound Phloem.- 3. Phloem Regeneration in Graft Unions.- a) Graft-Union Development.- b) Translocation Between the Graft Partners in Relation to Phloem Regeneration.- c) Symplastic Connections Between the Graft Partners.- d) Mechanism of Secondary Plasmodesmata Formation.- 4. Conclusion.- References.- IV. Reproductive Development in Seed Plants: Research Activities at the Intersection of Molecular Genetics and Systematic Botany.- 1. Introduction.- 2. From Vegetative to Floral Apices - a Developmental Continuum.- 3. Developmental Pathways of Inflorescences.- a) Computer Stimulation, Terminological Questions.- b) Inflorescence Development in Grasses (Poaceae).- c) Inflorescence Development in Leguminosae and Some Other Dicotyledons.- d) Inflorescence Development in Asteraceae and Other Angiosperms with Pseudanthia.- e) Cone and Ovule Ontogeny in Gymnosperms (Mainly Conifers).- 4. Developmental Pathways of Flowers.- a) How to Define Whorls and Cycles.- b) Flexibility of Floral Construction, Meristic Variation, and Chaotic Flowers in Angiosperms.- c) Polyandrous Flowers in Dilleniidae and Rosidae (“Mid-level Dicotyledons”).- d) Development of Highly Synorganized Flowers with Cyclic Phyllotaxis (Asteridae, Orchids).- e) Some Comments on Gynoecium Development.- f) Fusion Events During Floral Morphogenesis.- 5. Homeosis, Heterochrony, and Developmental Mutants.- a) Fashionable Concepts.- b) Naturally Occurring Homeosis in Flowering Plants.- c) Naturally Occurring Heterochrony in Flowering Plants.- d) Developmental Mutants and the Arabidopsis-Antirrhinum Model of Floral Morphogenesis.- 6. Cladistic Analysis Using Floral Developmental Characters.- 7. Evolution of Floral Ontogenies.- 8. Outlook.- References.- B. Physiology.- I. Plant Water Relations.- 1. Water Relations of Cells and Tissues.- 2. Root Water Uptake and Water Movement Through the Plant.- 3. Stomatal Behavior and Transpirational Water Loss.- 4. Water Relations of Seeds and During Early Germination Stages.- 5. Effects of Water Shortage on Growth and Metabolism.- 6. Implications of Waterlogged Conditions.- 7. Habitat Water Relations and Plant Performance.- 8. Water Relations in Poikilohydric Plants.- References.- II. The Transport Phloem. Specifics of its Functioning.- 1. Functions of the Transport Phloem.- 2. (Ultra)structure of the Transport Phloem.- 3. Membrane Potential Mapping of Stem Tissues.- 4. Symplastic Discontinuity Between SE/CC Complex and Adjoining Cells.- 5. Energy Channeling Between Sieve Element and Companion Cell.- 6. Release/Retrieval Via Pump/Leak Systems in the SE/CC Complex.- 7. Sugar Uptake by the SE/CC Complex.- 8. Sugar Release from the SE/CC Complex.- 9. Alternative or Parallel Apoplastic and Symplastic Unloading from the SE/CC Complex into Axial Sinks.- 10. (Un)loading of Storage Carbohydrates in the Transport Phloem.- 11. Driving Forces of Phloem Transport.- 12. PMF Gradients Along the Phloem Pathway.- 13. Potential Consequences of Functioning of the Transport Phloem for the Relative Growth Rate.- 14. Signaling Along the Phloem Pathway.- References.- III. Progress in Chlorophyll Fluorescence Research: Major Developments During the Past Years in Retrospect.- 1. Introduction.- 2. Progress in Noninvasive Modulation Measuring Techniques.- a) Modulation Fluorometry.- b) Related Modulation Spectroscopy.- 3. The Saturation Pulse Method and Separation of Different Forms of Nonphotochemical Quenching.- a) The Saturation Pulse Method.- b) Separation of Different Forms of Nonphotochemical Quenching.- 4. Plant Stress Investigations.- a) Fluorescence as a Nondestructive Tool in Stress Research.- b) Photoinhibition and Photoinhibitory Quenching.- 5. Photosynthetic Rate Determination from Fluorescence Measurements.- a) Expressions for Rate Determination on the Basis of Quenching Analysis.- b) Comparison of Effective Quantum Yields of PS I and PS II.- 6. Mechanisms of Regulated Radiationless Energy Dissipation.- 7. Membrane Energization and Nonassimilatory Fluxes.- 8. Outlook.- References.- IV. Photosynthesis: Carbon Metabolism Twenty Years of Following Carbon Cycles in Photosynthetic Cells.- 1. Introduction.- 2. Uptake of CO2.- a) Cyanobacteria.- b) Eukaryotes.- c) Carbonic Anhydrase.- 3. RuBP Carboxylase.- a) Regulation of RuBP Carboxylase Activity.- 4. Other Calvin Cycle Enzymes.- a) Light-Mediated Regulation.- 5. Chloroplast Starch.- 6. Cytosolic Sucrose Biosynthesis: Control by Cytosolic FBPase and Sucrose-P-Synthase.- 7. Mitochondrial Respiration.- 8. Photorespiration.- 9. Stress and Photosynthetic Carbon Metabolism.- 10. C4 Photosynthesis.- a) PEP Carboxylase.- 11. C3–C4 Intermediate Photosynthesis.- 12. Crassulacean Acid Metabolism (CAM).- 13. Concluding Comment.- References.- V. Metabolism of Inorganic Nitrogen Compounds.- 1. Assimilatory Nitrate Reduction.- 2. Nitrogen Fixation by Free-Living Microorganisms.- 3. Nitrogen Fixation in Symbiosis.- 4. Denitrification.- 5. Nitrification.- References.- VI. Secondary Plant Substances Further Topics of the Phenylpropanoid Metabolism.- 1. Introduction.- 2. Quinones.- 3. Lignans.- 4. Capsaicinoids.- References.- VII. Mineral Nutrition: Tropical Savannas.- 1. Introduction: The Concept of Savanna.- 2. Recent Reviews on Savannas in General and Nutrients in Particular.- 3. Savanna Soils and the Concept of Nutrient Availability.- 4. Correlations Between Soil Fertility and Savanna Composition and Structure.- 5. Grassland Productivity and Nutrient Availability.- 6. Biological Interactions Regulating Nutrient Availability in Savanna Environments.- a) Grass-Tree Interactions.- b) Mound-Building Termites and Leaf-Cutting Ants.- c) Mycorrhiza.- d) N2-Fixation by Legume-Rhizobia Associations.- e) N2-Fixation by Free-Living Microorganisms.- 7. Nutrient Cycling and the Effect of Fire: Are Savannas Sources or Sinks for Biogenic Nutrients?.- a) Nitrogen Losses Through Denitrification and Ammonification.- b) Nitrogen Losses Through Fire.- c) Nitrogen Balances.- 8. Conclusions.- References.- VIII. Developmental Physiology: Signal Transduction.- 1. Introduction.- 2. Perception of the Signal.- a) Growth Substances.- b) Pathogens.- 3. Transformation of the Signal.- 4. Amplification of the Signal: Secondary Messengers.- a) Phosphoinositides.- b) Ca2+.- c) Fatty Acid-Derived Second Messengers.- d) Sphingolipids.- e) pH.- f) Electrical Fields and Waves.- 5. The Transduction of the Signal: Protein Kinases.- 6. The Target(s) and the Cellular Response.- 7. Outlook.- References.- C. Genetics.- I. Replication.- 1. Introduction.- 2. Bacterial Conjugation.- 3. The Origin of Transfer.- 4. Transfer Replication.- 5. Regulation of DNA Transfer.- 6. Summary.- References.- II. Recombination: Sexual Reproduction — a Tool for Outcrossing and Recombination of Genetic Material.- 1. Introduction: The Benefits of Sexual Reproduction.- 2. Genetic Control of Sexual Reproduction — the Mating Type Genes.- a) The Ascomycetous Yeast Saccharomyces cerevisiae.- b) The Ascomycetous Yeast Schizosaccharomyces pombe.- c) Filamentous Ascomycetes: Cochliobolus heterostrophus, Neurospora crassa and Podospora anserina.- d) The Hemibasidiomycete Ustilago maydis.- e) Holobasidiomycetes: Coprinus cinereus and Schizophillum commune.- 3. The Significance of Mating Type Switching.- 4. Unlike Other Genes, Intragenic Recombination May Be Prevented in Mating Type Genes.- 5. Conclusions.- References.- III. Isolation of Plant Genes by T-DNA and Transposon Mutagenesis — Gene Tagging.- 1. Introduction.- 2. T-DNA Mutagenesis.- a) T-DNA Integration.- b) T-DNA-Mediated Gene Tagging.- 3. Transposon Mutagenesis.- a) Transposons.- b) Transposon-Mediated Gene Tagging.- 4. Prospects.- References.- IV. Function of the Genetic Material: Transposable Elements in Lower Eukaryotes.- 1. Introduction.- 2. LTR-Transposons.- 3. Non-LTR Retrotransposons.- 4. Origin and Evolution of Retroelements.- 5. Transcription and Expression of Retrotransposon Functions.- 6. Reverse Transcription and Integration.- 7. Conclusions.- References.- V. Extranuclear Inheritance: Mitochondrial Genetics.- 1. Introduction.- 2. Mitochondrial Genomes.- a) Complete DNA Sequence of Mitochondrial DNA from Chlamydomonas reinhardtii and Marchantia polymorpha.- b) Paternal Inheritance of Mitochondrial DNA.- 3. Mitochondrial Mutants of Higher Plants.- 4. Components for Mitochondrial Transcription and Replication: an Evolutionary Mosaic in Yeast.- 5. RNA Processing and Splicing.- 6. RNA Editing.- 7. Regulation of Mitochondrial Translation by Nuclear Genes.- 8. Protein Import into Mitochondria.- References.- VI. Extranuclear Inheritance: Linear Protein-Primed Replicating Genomes in Plants and Microorganisms.- 1. Introduction.- 2. Occurrence and Structure.- 3. Replication Mechanism.- 4. Prokaryotic Linear Elements.- 5. Cytoplasmic Elements.- a) Fundamentals.- b) Applied Aspects.- 6. Mitochondrial Plasmids.- 7. Phylogenetic Relationships.- 8. Prospects.- References.- VII. Molecular Genetics of Phytopathogenic Fungi.- 1. Introduction.- 2. Molecular Genetic Methods: New Tools for the Study of Fungus-Plant Interactions.- 3. Applications and Achievements.- a) Identification and Characterization of an Avirulence Gene.- b) Cutinase and Penetration.- c) Toxins.- d) Phytoalexin Metabolism.- e) DsRNA Involved in Hypovirulence.- 4. Conclusion.- References.- D. Taxonomy.- I. Systematics of the Bryophytes.- 1. General Aspects.- 2. Morphology, Anatomy.- 3. Chemistry.- 4. Systematics and Evolution.- a) General.- b) Monographs, Revisions.- c) Cytology.- d) Fossil Bryophytes.- 5. Floristics.- 6. Geography.- 7. Ecology.- a) General.- b) Pollution.- References.- II. Systematics of the Pteridophytes.- 1. Systematics.- 2. Bibliography, Collections, Nomenclature.- 3. Floristics.- 4. Geography and Ecology.- 5. Morphology and Anatomy.- 6. Chemotaxonomy.- 7. Cytotaxonomy, Biosystematics, Hybridization.- 8. Folklore, Uses.- 9. Fern Allies.- References.- E. Geobotany.- I. The History of Flora and Vegetation During the Quaternary.- 1. Paleoecology of the Younger Part of the Last Glaciation.- 2. Last Interglacial and the Beginning of the Last Glaciation.- 3. Pleistocene Vegetation History of Siberia, the Far East, and Central Asia.- 4. Problems of the European Middle Pleistocene Vegetation History.- 5. Correlation of Old and Middle Pleistocene Sediments.- 6. Paleoecology of Southeasternmost Europe and Middle Asia.- 7. Human Influences on Natural Ecosystems and the History of Soils.- References.- II. Plant Geography.- 1. Trends of Investigation.- 2. Terminology.- 3. Taxonomic and Floristic Foundations of Plant Geography.- a) New Findings and Range Extensions.- b) Distribution of Marine Algae.- c) New Floras.- ?) Large Monographic Floras.- ?) Regional Flora Handbooks.- ?) Local and State Floras (Eurasia and Australia).- 4. Plant Distribution Mapping.- a) Grid Mapping Projects.- b) Dot Maps.- c) Discussion of the Distribution Patterns.- 5. Chorology and Taxonomy.- 6. Reconstruction of Geographic Origin and Migration Routes.- 7. Vicariance Biogeography and Geographic Speciation.- 8. Sernander’s Nunatak Hypothesis.- 9. Ecological Factors of Plant Distribution.- a) Climate.- b) Edaphic Factors.- c) Dispersal.- 10. Man’s Impact on Plant Distribution.- 11. Phytogeographic Subdivision of the Continents.- References.- III. Ecological Aspects of Nitrogen Nutrition.- 1. Introduction.- 2. The Use of the Stable 15N Isotope in Ecophysiological Research.- a) Methodology.- b) Nitrogen Fixation in Natural Ecosystems.- c) Insectivorous Plants.- d) Parasitic Plants.- 3. Nitrogen Assimilation and Nitrogen Allocation in Relation to Photosynthesis and Plant Performance.- a) Nitrate or Ammonium?.- b) NO3- Assimilation Where?.- c) Nitrogen Allocation.- 4. Nitrogen Deposition.- 5. Outlook.- References.- F. Special Topics.- I. Floral Ecology Report on the Years 1988 (1987) to 1991 (1992).- 1. Introduction.- 2. Functional Aspects of Flowers and Inflorescences, Flower Longevity, Metabolism, and Movement.- 3. Means of Attraction, Rewards.- a) Color Vision, Visual Patterns, and Pigmentation.- b) Production of Scent and Heat.- c) Nectaries and Nectar.- d) Oil Secretion and Oil-Flowers.- e) Pollen and Pollen Presentation.- 4. Pollinator Behavior, Pollinator Efficiency, Flower Constancy, Foraging Strategies.- 5. Flower Classes and Their Evolution.- a) Zoophily.- ?) Evolution and Pollination of Early Angiosperms; Cantharophily, Flies and Thrips as Flower Visitors.- ?) Melittophily and Ant Pollination.- ?) Psychophily, Sphingophily, and Phalenophily.- ?) Ornithophily.- ?) Mammal Pollination and Visits of Lizards.- b) Anemophily and Hydrophily.- 6. Pollination of Particular Groups; Flower Biological Radiation.- a) Differentiation of Various Angiosperms at the Species, Genus, and Family Level.- b) Ficus.- c) Orchids.- d) Economy of Pollination and Crop Plants.- 7. Breeding Systems and Gender Distribution.- a) Pollen-Pistil Interaction.- b) Incompatibility Versus Compatibility, Cleistogamy; Apomixis.- c) Heterostyly.- d) Sex Distribution; Monoecism Versus Dioecism, and the Costs and Benefits of Reproduction.- 8. Pollination Studies at the Community Level, Distribution of Flower Types, Flowering Phenology, and Nature Preservation.- References.- II a. Mycorrhizae: Ectomycorrhiza and Ectendomycorrhiza.- 1. Ectomycorrhiza.- a) Symbiotic Organisms and Morphology/Anatomy of the Symbiotic Organs.- ?) Keys, Including Detailed Descriptions of Ectomycorrhizae.- ?) Comprehensive Descriptions of Selected Ectomycorrhizae.- ?) Unidentified Ectomycorrhizae Named Binomially.- ?) Verification of Ectomycorrhizal Nature of Fungi, Including Short Descriptions of Ectomycorrhizae.- ?) Strain Variability of Fungi Regarding Ectomycorrhizae Formation.- ?) Verification of Ectomycorrhizal Nature of Some Selected Plants, Including Short Descriptions of Ectomycorrhizae.- ?) Influence of Tree Clones on Ectomycorrhiza Formation.- b) Ontongeny and Ultrastructure.- c) Pigments.- d) Nucleic Acid Researches.- e) Physiology.- ?) Protoplasts.- ?) Substances Assumed as Important for Formation of Ectomycorrhizae.- i) Hormones.- ii) Phenolics.- ?) Recognition.- ?) Enzymes.- ?) Carbon Nutrition of Ectomycorrhizae.- ?) Growth Responses of Plants.- ?) Phosphate Nutrition.- ?) Nitrogen Nutrition.- ?) Micronutrients.- ?) Water.- f) Ecology.- ?) Ecological Laboratory Research.- ?) Researches in Natural Habitats.- ?) Coexistence with Other Organisms.- i) Fungi.- ii) Bacteria.- iii) Animals.- iv) Plants.- ?) Influences by Man.- i) Fertilization with Lime or Nitrogen.- ii) Pesticides.- iii) Pollution.- iv) Afforestation, Clear-Cut.- g) Methods.- h) Reviews.- 2. Ectendomycorrhiza.- 3. Some Highlights of This Report Period.- References.- II b. Symbioses: Mycorrhizae.- 1. VA-Mycorrhizae.- a) Taxonomy of Endophytes.- b) Physiology and Effects on Plants.- c) Ecology.- 2. Ericales-Mycorrhizae.- 3. Orchidaceae-Mycorrhizae.- References.