Temporal and Spatial Regulation of Plant Genes

First attempts to isolate plant genes were for those genes that are abun­ dantly expressed in a particular plant organ at a specific stage of devel­ opment. However, many important gene products are produced in a very minute quantity and in specialized cell types. Such genes can now be isolated using a variety of approaches, some of which are described in this volume. The rapid progress during the last decade in regeneration of a number of crop plants and the availability of molecular tools to introduce foreign genes in plants is allowing the engineering of specific traits of agri­ cultural importance. These genes must, however, be regulated in a spatial and temporal manner in order to have desired effects on plant devel­ opment and productivity. The habitat of plants necessitate adaptive responses with respect to the environmental changes. Starting from germination of the seed, the plant begins to sense environmental cues such as moisture, light, temperature and the presence of pathogens, and begins to respond to them. Little is known about various signal transduction pathways that lead to biochemical and morphogenetic responses, in particular, transition from vegetative to reproductive phase. With the availability of tools to generate specific mutations via transposon tagging, identification and isolation of genes affecting these processes may be facilitated. Transfer of these genes into heterologous environments will allow understanding of the complex processes that control plant development.

1 Arabidopsis as a Tool for the Identification of Genes Involved in Plant Developmen.- I. Introduction.- II. Phytohormone Mutants.- A. Introduction.- B. Auxin.- C. Ethylene.- D. Gibberellins.- E. Abscisic Acid.- III. Environmental Regulation of Growth and Development.- A. Introduction.- B. Tropic Responses.- C. Phytochrome.- D. Flowering Induction.- IV. Conclusions and Future Directions.- V. References.- 2 Regulation of Gene Expression During Seed Germination and Postgerminative Developmen.- I. Introduction.- II. Differential Gene Expression Underlies Seed Germination.- III. Spatial Regulation of Postgermination-Abundant Genes.- IV. Activation of Postgermination-Abundant Genes.- V. Future Directions.- VI. References.- 3 Genes Involved in the Patterns of Maize Leaf Cell Divisio.- I. Introduction.- II. The Shoot Apical Meristem as a Self-Regulating Unit.- III. Heterochrony.- IV. Maize Leaf Mesophyll and Epidermis Lineage Maps.- V. Leaf Vascularization and Development Compartments.- VI. The Importance of Periclinal Divisions.- VII. Strict Versus Loose Programming of Epidermal Cell Division.- VIII. Alternative Models Involving the Programming of Cell Division.- IX. The Ligule and Mutants that Affect It.- X. Kn 1: Neomorphic Mutants that Induce the Epidermis to Divide.- XI. Conclusions About Leaf and Ligule Development Derived from Mutant Analyses, and the Concept of Cell Age Identity.- XII. Where Are the Molecules.- XIII. References.- 4 Molecular Analysis of Genes Determining Spatial Patterns in Antirrhinum majus.- I. Introduction.- II. Cis-Acting Mutations.- A. Stable cis-Acting Mutations.- B. Unstable cis-Acting Mutations.- III. Trans-Acting Mutations.- IV. Mutations Which Act Both in cis and trans.- V. Conclusions.- VI. References.- 5 Isolation of Differentially Expressed Genes from Tomato Flower.- I. Introduction.- II. Screening for Floral-Specific cDNAs.- III. Organ and Temporal Specificity of Floral Clones.- IV. Tissue Specificity of Floral Clones.- V. Discussion.- VI. References.- 6 Anther- and Pollen-Expressed Gene.- I. Introduction.- A. Anther and Microsporangium Development.- B. Summary of Meiosis, Pollen, and Pollen Tube Development.- II. Gene Expression in the Anther.- A. The Tapetum.- B. Other Anther Tissues.- III. Gene Expression in the Developing Male Gametophyte.- A. Specific Transcription and Translation.- B. Estimates of Numbers of Genes Expressed in Pollen.- C. Cloning of Pollen-Expressed Genes and the Pattern of Transcription of Specific mRNAs.- D. Overlap of Sporophytic and Gametophytic Gene Expression.- E. Sperm Cells.- IV. References.- 7 Self-Incompatibility Genes in Flowering Plant.- I. Introduction.- II. Homomorphic Incompatibility.- A. The General Features of Gametophytic Self-Incompatibility.- B. The General Features of Sporophytic Self-Incompatibility.- III. Heteromorphic Incompatibility.- IV. Nature of the Self-Incompatibility Reaction.- V. Nature of the S-Gene Products.- A. Gametophytic Systems.- 1. Nicotiana alata.- 2. Petunia hybrida.- 3. Lycopersicon peruvianum.- 4. Prunus avium.- 5. Lilium longiflorum.- 6. Trifolium pratense.- B. Sporophytic Systems.- 1. Brassica oleracea.- 2. Brassica campestris.- VI. Studies of the Molecular Basis of Self-Incompatibility.- VII. Concluding Comments.- VIII. References.- 8 Regulatory Circuits of Light-Responsive Gene.- I. Introduction.- II. Multiplicity of Light Effects.- A. Photomorphogenesis.- B. Effects on Gene Expression.- C. Rhythms.- III. Effectors of Photoreception.- A. Phytochrome.- B. Signal Transduction.- C. Cis-Acting DNA Sequences.- D. Trans-Acting Factors.- IV. Conclusions.- V. References.- 9 Regulation of Gene Expression by Ethylen.- I. Introduction.- A. Plant Hormones.- B. Ethylene and the Control of Tomato Fruit Ripening.- C. Induction of the Gene Expression by Exposure to Exogenous Ethylene.- D. A Model System for Studying Hormonal Regulation of Gene Expression During Plant Development.- II. Analysis of Ethylene-Inducible Gene Expression.- A. Isolation of cDNA Clones.- B. Induction of Gene Expression by Exogenous Ethylene in Unripe Tomato Fruit.- C. Activation of Gene Expression and Ethylene Production During Tomato Fruit Development.- D. Repression of Gene Expression by a Competitive Inhibitor of Ethylene Action.- III. Discussion.- IV. References.- 10 Root Nodule Symbiosis: Nodulins and Nodulin Gene.- I. Introduction.- II. An Overview of Legume Nodulation.- III. Induction of Plant Genes Coding for Nodulins.- A. Nodulin Structure and Function.- 1. Leghemoglobins.- 2. Nitrogen-Assimilatory Enzymes.- a) Glutamine Synthetase.- b) Uricase II.- c) Xanthine Dehydrogenase.- d) Purine Nucleosidase.- 3. Enzymes Involved in Carbon Metabolism.- a) Sucrose Synthas.- 4. Nodulins of Unknown Functions.- a) Nodulin-A Family.- b) Peribacteroid Membrane (pbm) Nodulins.- c) Early Nodulins.- d) “Nodulin-25” of Alfalfa.- B. Regulation of Nodulin Gene Expression.- 1. Induction of Early Nodulin Genes Does Not Require Intracellular Bacteria or Infection Threads.- 2. Expression of Late Nodulins Requires Infection Threads or Intracellular Bacteria.- 3. Some Nodulins May Require Nitrogen Fixation for Induction.- 4. Nodulin Gene Regulation at the Molecular Level: cis-Regulatory Sequences.- 5. Physiological Factors Involved in Induction of Nodulin Genes.- IV. Rapid Evolution of Legume-Rhizobium Symbiosis.- V. References.- 11 Structure and Expression of Plant Genes Encoding Pathogenesis-Related Protein.- I. Introduction.- A. Occurrence of PR Proteins.- B. Induction of PR Proteins.- C. PR Proteins and Acquired Resistance.- II. Characteristics of PR mRNAs and Genes.- A. cDNA Cloning of PR mRNAs.- B. Genes Corresponding to Groups A, B, C and G.- C. Genes Corresponding to Groups D, E and F.- III. General Conclusion.- A. Role of PR Proteins.- B. Prospects for Future Research.- IV. References.- 12 Proteinase Inhibitor Gene Families: Tissue Specificity and Regulatio.- I. Introduction.- II. Developmentally Regulated Proteinase Inhibitor Genes in Seeds, Tubers, and Fruit.- III. Wound-Inducible Proteinase Inhibitor Genes in Leaves.- IV. Summary.- V. References.- 13 Cell Wall Extensin Gene.- I. Cell Walls.- II. Extensin Networks.- A. Insoluble Extensins.- B. Soluble Extensins.- C. Extensin Crosslinking.- III. Extensin Genes.- A. Cloning Extensins.- B. Functional Domains.- C. Gene Regulation.- IV. Prospects.- V. References.- 14 The Expression of Heat Shock Genes — A Model for Environmental Stress Respons.- I. Introduction.- A. The Heat Shock Response.- B. Groups of Related Heat Shock Proteins.- C. Heat Shock and Other Environmental Stresses.- II. Molecular Biology of Heat Shock Genes.- A. Sequence Homology Among Small Heat Shock Proteins.- B. Heat Shock Promoter and Upstream Sequences.- C. Heterologous Expression of hs Genes in Transgenic Plants.- III. General Conclusions.- IV. References.- 15 Protein Transport in Plant Cell.- I. Introduction.- II. The Secretory Pathway.- III. Post-Translational Transport.- A. The Nucleus.- B. The Chloroplast.- 1. Import.- 2. Fusion Proteins.- 3. Mutants in Envelope Translocation.- 4. Mutants in Thylakoid Translocation.- 5. Processing.- C. The Mitochondrion.- D. Endosomes.- IV. Conclusions.- V. References.- 16 Genetic Engineering of Herbicide Resistance Gene.- I. Introduction.- II. Identification and Engineering of Herbicide Resistance Genes.- A. Glyphosate Resistance.- B. Phosphinothricin Resistance.- C. Sulfonylurea and Imidazolinone Resistance.- III. Conclusions.- IV. References.- 17 Virus Cross-Protection in Transgenic Plant.- I. Introduction.- A. Classical Cross-Protection: Applications and Limitations.- B. Proposed Mechanisms of Cross-Protection.- II. Genetic Transformation to Produce Virus Resistant Plants.- A. Expression of Viral Coat Protein Coding Sequences in Transgenic Plants.- B. Resistance to Virus Infection in Transgenic Plants.- C. Elucidating the Mechanism(s) of Engineered Protection.- D. Expression of Other Viral Sequences in Transgenic Plants.- III. Field Testing of Virus Protection in Transgenic Plants.- IV. Conclusions.- V. References.