Plant Genetic Engineering

1 Plant gene structure and expression.- 1.1 Introduction.- 1.2 Protein-coding genes.- 1.2.1 Structure of protein-coding genes.- 1.3 Regulation of plant gene expression.- 1.3.1 Transcriptional regulation.- 1.3.2 DNA methylation.- 1.3.3 Post-transcriptional regulation.- 1.3.4 mRNA-processing.- 1.4 Translational control.- 1.5 Differential expression.- 1.5.1 Multigene families.- 1.5.2 Pseudogenes.- 1.6 RNA-coding genes.- 1.7 RNA genes transcribed by RNA polymerase I.- 1.8 RNA genes transcribed by RNA polymerase II.- 1.9 RNA genes transcribed by RNA polymerase III.- References.- 2 Gene transfer to plants.- 2.1 Introduction.- 2.1.1 General concepts.- 2.1.2 Target plant cells for transformation.- 2.1.3 Transformation vector considerations.- 2.2 Vectors based on the Agrobacterium Ti plasmid.- 2.2.1 The Ti plasmid as a natural plant transformation vehicle.- 2.2.2 The process of T-DNA transfer.- 2.2.3 Vectors based on the Ti plasmid.- 2.2.4 Transformation techniques using Agrobacterium vectors.- 2.3 Physical DNA delivery methods.- 2.3.1 Chemically stimulated plasmid uptake into protoplasts.- 2.3.2 Transformation of protoplasts by electroporation.- 2.3.3 Microinjection, 'macroinjection' and microprojectiles.- 2.3.4 Virus vectors for gene transfer to plants.- 2.4 Uses of gene transfer technology.- 2.4.1 Properties of transformed plants.- 2.4.2 Plant variety improvement: addition of useful traits to crop species.- 2.4.3 Analysis of gene regulation and basic biochemical and molecular studies.- 2.4.4 Genetic mapping and gene cloning.- References.- 3 Developing herbicide resistance in crops by gene transfer technology.- 3.1 Introduction.- 3.2 Modification of the target of herbicide action.- 3.2.1 Glyphosate.- 3.2.2 Sulphonylureas and imidazolinones.- 3.2.3 l-Phosphinothricin.- 3.2.4 Atrazine.- 3.2.5 Conclusion.- 3.3 Detoxification or degradation of the herbicide.- 3.3.1 Plant detoxifying enzymes.- 3.3.2 Bacterial detoxifying enzymes.- 3.3.3 Conclusion.- 3.4 Perspectives.- References.- 4 Genetic engineering of plants for insect resistance.- 4.1 Introduction.- 4.1.1 Monoculture.- 4.1.2 Absence of inherent resistance.- 4.1.3 Agrochemicals.- 4.2 Defensive methods used by plants against insect attack.- 4.2.1 Defensive mechanisms and plant breeding.- 4.2.2 Insecticidal plant metabolites.- 4.3 Insecticidal compounds from other sources.- 4.3.1 Chemical insecticides.- 4.3.2 Bacterial toxins.- 4.3.3 Biological control.- 4.4 Constraints on the genetic engineering of plants for insect resistance.- 4.5 The production of insect-resistant transgenic plants: two case studies.- 4.5.1 Transgenic plants expressing Bt toxins.- 4.5.2 Transgenic plants expressing protease inhibitors.- 4.6 Future prospects.- References.- 5 Virus-resistant plants.- 5.1 Introduction.- 5.2 Basic concepts of resistance to plant virus infection.- 5.3 Key features of the infection cycles of positive-strand RNA plant viruses.- 5.3.1 Plant-to-plant spread of viruses.- 5.3.2 Virus entry, uncoating and early translation.- 5.3.3 Modes of gene expression.- 5.3.4 Replication of virus RNA.- 5.3.5 Virus assembly.- 5.3.6 Cell-to-cell and long-distance movement.- 5.4 Molecular bases and exploitation of naturally occurring virus resistance genes.- 5.4.1 Resistance operating by inhibition of virus replication in single cells.- 5.4.2 Resistance restricting virus cell-to-cell movement.- 5.4.3 Resistance mediated by induction of a host hypersensitive response.- 5.4.4 Prospects for cloning and manipulating naturally occurring virus resistance genes.- 5.5 Construction and expression of artificial resistance genes in transgenic plants.- 5.5.1 The cross-protection phenomenon as a source of potential resistance genes.- 5.5.2 Cross-protection in transgenic plants expressing a mild virus strain.- 5.5.3 Resistance in transgenic plants expressing virus coat protein genes.- 5.5.4 Disease attenuation in transgenic plants expressing satellite RNAs.- 5.5.5 The antisense RNA approach.- 5.5.6 Virus-resistant plants expressing sense RNA.- 5.5.7 Potential of ribozymes in the construction of artificial virus resistance genes.- 5.6 Future prospects.- References.- 6 Targeting of proteins to chloroplasts and mitochondria.- 6.1 Introduction.- 6.2 Structure and biogenesis of chloroplasts.- 6.3 Import of stromal proteins.- 6.3.1 Binding to import receptors in the chloroplast envelope.- 6.3.2 Translocation across the envelope membranes.- 6.3.3 Proteolytic maturation of imported stromal proteins.- 6.3.4 Structure and location of stroma-targeting signals.- 6.4 Transport of proteins into the thylakoid system.- 6.4.1 Biogenesis of thylakoid lumen proteins.- 6.4.2 Import and integration of the light-harvesting chlorophyll-binding protein.- 6.5 Import of proteins into the envelope membranes.- 6.6 Transport of proteins into mitochondria.- 6.6.1 Early stages in the import pathway.- 6.6.2 Transport across the mitochondrial membranes.- 6.6.3 Sorting of imported mitochondrial proteins.- 6.6.4 Transport of proteins into plant mitochondria.- References.- 7 Protein transport and targeting within the endomembrane system of plants.- 7.1 Introduction.- 7.2 Biogenesis of endomembrane compartments.- 7.2.1 Endoplasmic reticulum.- 7.2.2 Nuclear envelope.- 7.2.3 Golgi apparatus.- 7.2.4 Cell surface.- 7.2.5 Vacuole.- 7.2.6 Protein bodies.- 7.2.7 Lipid bodies.- 7.2.8 Peroxisomes.- 7.3 Mechanisms of protein transport.- 7.3.1 Endoplasmic reticulum entry.- 7.3.2 Endoplasmic reticulum-to-Golgi transport.- 7.3.3 Intra-Golgi transport.- 7.3.4 Post-Golgi transport.- 7.4 Mechanisms of protein sorting.- 7.4.1 Endoplasmic reticulum entry-the signal sequence.- 7.4.2 Endoplasmic reticulum retention.- 7.4.3 Secretion.- 7.4.4 Protein body/vacuole localisation.- 7.4.5 Peroxisome localisation.- 7.5 Glycosylation and post-translational modification.- 7.5.1 N-linked glycosylation.- 7.5.2 O-linked glycosylation.- 7.5.3 Proteolytic processing.- 7.5.4 Other post-translational modifications.- References.- 8 Identification and characterisation of tissue-specific genes from flowers.- 8.1 Introduction.- 8.2 Identification of flower-specific genes.- 8.3 Characterisation of gene expression in floral organs.- 8.4 Tissue and cell specificity of gene expression in flowers.- 8.5 Discussion.- References.