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.

Inhaltsangabe1 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. Isola