Genetic Improvement of Tomato

The esculent Lycopersicon esculentum, long thought to be poisonous, has become a major U. S. food crop and source of vitamins and minerals, thanks largely to genetic modification and new production technology Rick (1978) Tomato (Lycopersicon esculentum Mill. ) is one of the most important solana­ ceous vegetable crops grown worldwide under outdoor and indoor conditions. It has become an important commercial crop so far as the area, production, industrial values and its contribution to human nutrition is concerned. During the past few decades tremendous developments have contributed to the knowledge and understanding of various areas of genetics, breeding and biotechnology and voluminous literature has been generated. The purpose of preparing this monograph is to give a comprehensive up-to-date treatment to the various aspects of genetic improvement of tomato. The emphasis has been placed on cytology, classical and molecular genetics, reproductive biology, germplasm resources, hybrid seed production, use of wild taxa, selection/ breeding methods, breeding for abiotic and biotic stresses, processing and quality breeding, improvement for mechanical harvesting, and biotechnology: tissue culture, protoplast fusion, and genetic transformation. These topics are presented in 22 different chapters. However, a few aspects have been discussed in more than one chapter. For example, seed production is treated in chapters 1, 4 and 8; molecular biology/genetic engineering in chapters 3 and 22 and heterosis in chapters 8 and 16.

Contenu

1 Introduction.- 1.1 Origin and History.- 1.2 Taxonomy.- 1.3 Economic Importance.- 1.4 Area and Production.- 1.5 History of Improvement.- 1.6 An Ideal Research Material.- 1.7 Seed Production.- 2 Cytology of Lycopersicon.- 2.1 Introduction.- 2.2 Mitosis.- 2.3 Meiosis.- 3 Genetics of Lycopersicon.- 3.1 Tomato as a Research Vehicle.- 3.2 Variability.- 3.3 Mutants and Genetic Stocks.- 3.4 Gene Linkage.- 3.5 Genetics of Quantitative Traits.- 4 Reproductive Biology in Tomato.- 4.1 Introduction.- 4.2 Floral Biology.- 4.3 Incompatibility.- 4.4 Artificial Hybridization.- 4.5 Genetic Male Sterility.- 5 Germplasm Resources in Lycopersicon.- 5.1 Introduction.- 5.2 Collection and Exploration.- 5.3 Evaluation and Utilization.- 5.4 Maintenance and Conservation.- 5.5 Descriptor.- 5.6 Extinction.- 6 Selection Systems for Tomato Improvement.- 6.1 Introduction.- 6.2 Improving Pedigree-Based Selection Systems.- 6.3 Population Improvement Systems.- 6.4 Selection for Combining Ability.- 6.5 Gametophytic Selection.- 6.6 Selecting Superior Parents.- 6.7 Factors Affecting Selection and Genetic Advance.- 7 Interspecific and Intergeneric Hybridization in Tomato.- 7.1 Introduction.- 7.2 Crossability.- 7.3 Hybrids and Segregating Progenies.- 7.4 Sesquidiploids.- 7.5 Barriers.- 7.6 Overcoming the Barriers.- 7.7 Transfer of Economic Attributes from Wild Species to Commercial Cultivars.- 7.8 Breeding Strategies and Limitations.- 8 Heterosis in Tomato Breeding.- 8.1 Introduction.- 8.2 Meaning of Heterosis.- 8.3 The Causes of Heterosis.- 8.4 Breeding of Ft Tomato Hybrids.- 8.5 Development of Hybrid Seed Production.- 8.6 Summary.- 9 Disease Resistance in Tomato.- 9.1 Introduction.- 9.2 Fungal Diseases.- 9.3 Bacterial Diseases.- 9.4 Virus Diseases.- 9.5 Conclusions.- 10 Insect and Mite Resistance in Tomato.- 10.1 Introduction.- 10.2 Tomato Species in Which Resistance to Insects or Mites Is Known.- 10.3 Insects and Mites to Which Resistance Is Known in Tomato Species.- 10.4 Known Mechanisms of Resistance.- 10.5 Conclusions.- 11 Root-Knot Resistance in Tomato.- 11.1 Introduction.- 11.2 Distribution.- 11.3 Pathology.- 11.4 Biology and Life History.- 11.5 Nematode Control.- 11.6 Breeding for Resistance.- 11.7 Screening for Root-Knot Resistance.- 11.8 Genetics of Resistance.- 11.9 Stability of Resistance.- 11.10 Mechanism of Resistance.- 11.11 Relationship of Root-Knot Nematodes to Other Tomato Root Diseases.- 11.12 Summary.- 12 Breeding for Environmental Stress Resistance in Tomato.- 12.1 Introduction.- 12.2 Cold Resistance.- 12.3 Heat Resistance.- 12.4 Drought Resistance.- 12.5 Excessive Moisture Resistance.- 12.6 Salt Resistance.- 12.7 Efficient Mineral Nutrition Uptake.- 12.8 Resistance to Herbicides.- 12.9 Ozone Resistance.- 13 Parthenocarpy in Tomato.- 13.1 Introduction.- 13.2 Types of Parthenocarpy.- 13.3 Sources.- 13.4 Expression.- 13.5 Genetics.- 13.6 Physiology.- 13.7 Quality of the Parthenocarpic Fruits.- 13.8 Methods of Screening for Parthenocarpy.- 13.9 Use of Parthenocarpy in Tomato Breeding.- 14 Breeding for Carotenoid Pigments in Tomato.- 14.1 Introduction.- 14.2 Regulation of Carotenogenesis.- 14.3 Function of Carotenoids.- 14.4 Characteristics of Carotenogenesis in Interspecific and Intercultivar Hybridization of Tomato.- 14.5 Express Methods for Assessing the Carotenoid Composition of Tomato Fruits.- 15 Breeding Tomato for Quality and Processing Attributes..- 15.1 Introduction.- 15.2 Fruit Quality.- 15.3 Breeding Methods.- 15.4 Testing and Evaluation of Breeding Lines.- 15.5 General Breeding Objectives.- 15.6 Specific Breeding Objectives.- 15.7 Future Prospect.- 16 Some Aspects of Breeding Tomato for Greenhouse Conditions.- 16.1 Introduction.- 16.2 Development of Cultivars and Hybrids.- 17 Breeding Tomato for Mechanized Harvesting.- 17.1 Introduction.- 17.2 Requirements of Tomato Cultivars for Mechanized Harvesting.- 17.3 Breeding for Uniform Ripening of Fruits.- 17.4 Breeding Tomatoes for Enhanced Fruit Firmness and Marketable Yield.- 17.5 Tomato Breeding for Pedicel Characteristics.- 17.6 Conclusions.- 18 Cell, Tissue and Organ Culture in Lycopersicon.- 18.1 Introduction.- 18.2 Callus and Cell Suspension Cultures.- 18.3 Root, Shoot and Plant Regeneration from Vegetative Material.- 18.4 Culture of Reproductive Organs (Anthers, Flowers, Ovaries, Embryos).- 19 Protoplast Culture and Somatic Hybridization in Lycopersicon.- 19.1 Introduction.- 19.2 Isolation and Culture of Protoplasts.- 19.3 Regeneration of Shoots and Plantlets from Isolated Protoplasts.- 19.4 Protoplast Fusion and Production of Somatic Hybrids.- 20 Genetic Variation in in-Vitro Cultures and Regenerated Plants in Tomato and Its Implications.- 20.1 Introduction.- 20.2 In Vitro Differentiation and Nuclear Processes.- 20.3 Phenotypic and Genetic Variation in Regenerated Plants.- 20.4 Variants or Mutants from Cell and Callus Cultures.- 20.5 Factors Influencing Variation.- 20.6 Conclusions.- 21 Isozymes in Lycopersicon.- 21.1 Introduction.- 21.2 Variations in Lycopersicon species.- 21.3 Applications in Breeding Practices.- 22 Genetic Transformation of Tomato and Prospects for Gene Transfer.- 22.1 Introduction.- 22.2 The Ti-Plasmid as Natural Gene Vector.- 22.3 Agrobacterium-Medizted Plant Cell Transformation.- 22.4 Direct Gene Transfer.- 22.5 Application of Genetic Transformation in Lycopersicon.- 22.6 Concluding Remarks.- References.