There has been recent rapid progress in the transformation of plants with foreign DNA, making use either of the natural routes of genetic invasion that viruses and bacteria have developed, or of chemical, mechanical and electrical tricks to make plant protoplast membranes permeable to nucleic acids. Genes integrated into plant virus genomes can be carried systemi cally from the initial site of infection into the rest of the plant. Genes placed between the borders of Agrobacterium tumefaciens T-DNA can be transferred into single cells or plant tissue, which then divides to produce wound calli, or as in the case of an Agrobacterium rhizogenes infection, grow out into new roots. Calli and roots can be grown into whole plants. If virus genomes are placed between the T-DNA borders, a very effective infectious route, termed "agroinfection", is established. Once inside a pro toplast, DNA finds its way into the nucleus where it can finally integrate into the resident chromosome and be expressed. Whether it can also find its way into chloroplasts is not yet clear, but at least translation products can be targeted into this organelle. Regeneration of whole organisms from single cells is a special feature of plants and offers a unique tool to study genes in a multicellular organism. In addition, as in animal cells, transcription and translation of trans forming genes can be studied in plant cells during "transient expression".

Inhalt
1 The Molecular Biology of Cauliflower Mosaic Virus and Its Application as Plant Gene Vector.- I. Introduction.- II. The Biology of Cauliflower Mosaic Virus.- III. The Development of CaMV into a Plant Gene Vector.- IV. Elements of CaMV as Tools in Plant Genetic Engineering.- V. Vector Based on Other Plant Viruses.- VI. Conclusion and Outlook.- VII. References.- 2 The Structure, Expression, Functions and Possible Exploitation of Geminivirus Genomes.- I. Introduction.- II. Genome Organisation.- III. Gene Expression.- IV. Gene Functions.- V. The Potential of Geminiviruses as Gene Vectors.- VI. References.- 3 cDNA Cloning of Plant RNA Viruses and Viroids.- I. General Introduction.- II. Construction of Full-Length cDNA Clones.- III. DNA Copies as Tools to Study the Molecular Biology of Plant RNA Viruses.- IV. Viroids and Satellites.- V. Diagnosis of Plant Diseases Using DNA Copies of Plant Viruses and Viroids.- VI. Conclusions and Future Aspects.- VII. References.- 4 Agroinfection.- I. Introduction.- II. Potential Applications of Agroinfection.- III. Perspectives.- IV. References.- 5 The Mechanism of T-DNA Transfer from Agrobacterium tumefaciens to the Plant Cell.- I. General Introduction.- II. Early Events of Transformation.- III. T-DNA Processing.- IV. Conclusions.- V. References.- 6 Molecular Analysis of Root Induction by Agrobacterium rhizogenes.- I. Introduction.- II. Taxonomy.- III. Ri Plasmid Structure.- IV. Ri T-DNA Organization.- V. T-DNA of Ri Transformed Plants.- VI. Endogenous T-DNA of Plants.- VII. Conclusions and Further Speculations.- VIII. References.- 7 Pathways to Plant Genetic Manipulation Employing Agrobacterium.- I. Introduction.- II. Biology of Agrobacterium tumefaciens Ti Plasmid.- III. Strategies for Inserting Genes into T-DNA.- IV. Practical Catalogue.- V. Getting Genes into Plants.- VI. Novel Applications of Ti Transformation.- VII. Prospects.- VIII. References.- 8 Plant Transposable Elements: Unique Structures for Gene Tagging and Gene Cloning.- I. Introduction.- II. Isolation and Characterization of a Transposable Element.- III. Transposable Elements as Molecular Probes for Gene Isolation.- IV. Conclusions.- V. References.- 9 Direct Gene Transfer to Plants.- I. Direct Gene Transfer.- II. Other Vectorless Gene Transfer Systems.- III. Direct Gene Transfer in Theoretical and Applied Genetics.- IV. References.- 10 Microinjection: An Experimental Tool for Studying and Modifying Plant Cells.- I. Introduction.- II. Recipient Cell Systems.- III. Resolution of Intracellular Compartments.- IV. Microinjection Methodology.- V. Genetic Transformation.- VI. Other Applications.- VII. Concluding Remarks.- VIII. References.- 11 Transformation of Chlamydomonas Reinhardtii.- I. Introduction.- II. Nuclear Transformation.- III. Prospects of Chloroplast Transformation in C. reinhardtii.- IV. Conclusions.- V. References.- 12 Induction of Expression in and Stable Transformation of an Algal Cell by Nuclear Microinjection with Naked DNA.- I. Introduction.- II. Acetabularia.- III. Techniques.- IV. Expression of Genomic RNA.- V. Expression of Genomic DNA.- VI. Expression of Genes and Gene Constructions.- VII. Regulation of Expression.- VIII. Transformation.- IX. Genetics.- X. Discussion.- XI. References.- 13 Transient Expression of DNA in Plant Cells.- I. Overview of Transient Assay Applications.- II. Transient Assays in Plant Cells.- III. Transient Expression after Electroporation-Mediated Gene Transfer.- IV. Discussion.- V. References.- 14 Plastid Transformation: A Progress Report.- I. Introduction.- II. Construction of Vectors for the Transformation of Plastids.- III. General Conclusions.- IV. References.- 15 Targeting Nuclear Gene Products into Chloroplasts.- I. Introduction.- II. Binding of Precursors to the Outer Membrane of the Chloroplast.- III. Translocation of Polypeptides Across the Envelope Membranes.- IV. Processing of Precursors to the Nature Polypeptide.- V. The Transit Peptide Itself can Mediate Import of Foreign Polpeptides.- VI. Structural Analysis of Chloroplast Transit Peptides.- VII. Experimental Analysis of Transit Peptides.- VIII. Future Prospects.- IX. References.