Beschreibung
Inhaltsangabe1 Introduction.- 2 Methods for Inducing Mutations.- 2.1 Mutagenic Agents and Related Problems.- 2.2 The Chimerical Structure of the M1 Plants.- 3 The Selection Value of Mutant Genes.- 4 The Seed Production of Mutants and the Alteration of Quantitative Characters.- 4.1 The Alteration of Quantitative Characters.- 4.2 Mutants with Increased Seed Yield.- 4.3 Released or Approved Mutant Varieties.- 5 The Utilization of Mutants in Crossbreeding.- 5.1 The Incorporation of Mutant Genes into the Genomes of Varieties or Strains.- 5.2 The Joint Action of Mutant Genes.- 5.2.1 Negative Interactions.- 5.2.2 Positive Interactions.- 6 The Alteration of the Shoot System by Means of Mutations.- 6.1 Mutants with Reduced Plant Height: Erectoides Types, Semidwarfs, Dwarfs.- 6.1.1 Barley.- 6.1.2 Rice.- 6.1.3 Bread and Durum Wheat; Other Gramineae.- 6.1.4 Dicotyledonous Crops.- 6.2 Mutants with Increased Plant Height.- 6.3 Mutants with Altered Stem Structure.- 6.3.1 Branching, Tillering.- 6.3.2 Stem Bifurcation.- 6.3.2.1 Bifurcated Mutants.- 6.3.2.2 Bifurcated Recombinants.- 6.3.3 Stem Fasciation.- 6.3.3.1 Fasciated Mutants.- 6.3.3.2 Fasciated Recombinants.- 6.3.4 Mutations in Fiber Plants.- 7 Alterations of Flower Shape, Color and Function.- 7.1 Flower Shapes and Flower Colors in Ornamentals.- 7.2 Inflorescences.- 7.3 Genetic Male Sterility.- 8 Leaf Mutants of Agronomic Interest.- 9 Mutations Affecting the Root System.- 10 The Alteration of Flowering and Ripening Times.- 10.1 Earliness.- 10.2 Lateness.- 10.3 Changes of the Photoperiodic Reaction.- 11 Mutations in Vegetatively Propagated Crops and Ornamentals.- 12 Heterosis.- 13 Disease Resistance.- 13.1 Resistance Against Fungi, Bacteria, and Viruses.- 13.1.1 Barley.- 13.1.2 Rice.- 13.1.3 Bread and Durum Wheat.- 13.1.4 Oats.- 13.1.5 Maize.- 13.1.6 Pearl Millet.- 13.1.7 Sugarcane.- 13.1.8 Dicotyledonous Crops.- 13.2 Resistance Against Animal Pathogens.- 13.3 Herbicide Tolerance.- 14 Drought Resistance, Heat Tolerance, Winterhardiness.- 15 Shattering and Shedding Resistance.- 16 The Pleiotropic Gene Action as a Negative Factor in Mutation Breeding.- 16.1 The Alteration of Pleiotropic Patterns Under the Influence of Changed Genotypic Background or Environment.- 16.2 Mutations of Closely Linked Genes.- 17 The Penetrante Behavior of Mutant Genes as a Negative Factor.- 18 The Adaptability of Mutants to Altered Environmental Conditions.- 18.1 The Reaction of Mutants to Different Natural Environments.- 18.2 The Reaction of Mutants Under Controlled Phytotron Conditions.- 19 The Alteration of Morphological and Physiological Seed Characters.- 19.1 Seed Size.- 19.2 Seed Shape.- 19.3 Seed Color.- 19.4 Physiological Seed Characters.- 20 The Alteration of Seed Storage Substances.- 20.1 Seed Proteins.- 20.1.1 The Characterization of Seed Proteins.- 20.1.2 Factors Influencing Protein Content and Composition.- 20.1.2.1 Environmental Factors.- 20.1.2.2 Endogenous Factors.- 20.1.3 Seed Protein Content of Different Varieties of the Same Species.- 20.1.4 Alteration of Seed Proteins Through Mutant Genes.- 20.1.4.1 Protein Mutants in Cereals.- 20.1.4.2 Protein Mutants in Legumes.- 20.2 Seed Carbohydrates.- 20.2.1 Maize.- 20.2.2 Barley and Other Cereals.- 20.2.3 Peas.- 20.3 Seed Lipids.- 21 Other Plant Substances.- 22 The Nutritional Value of Mutants.- 22.1 Maize Mutants.- 22.2 Barley Mutants.- 22.3 Sorghum Genotypes.- 22.4 Pea Mutants.- 23 General Aspects of Mutation Breeding with Regard to the Improvement of Seed Storage Substances.- References.
Mutation breeding has been introduced into modern plant breeding in the early 1940's. In spite of pessimistic predictions, the application of experimental mutagenesis has led to encouraging results demonstrating that mutation breeding is a well-functioning method in many crops. So far, more than 500 varieties, developed by means of induced mutations, have been officially released; others have been approved for registration. Many mutants with characters of agronomic interest cannot be utilized directly because of their unsatisfying yielding capacities, or of other negative traits which are partly due to the pleiotropic action of the mutant genes. Sometimes their negative selection value can be overcome by transferring them into the genomes of other varieties. According to experience available, the efficiency of mutant genes can conSiderably vary depending on the genotypic background in which they become effective. The interactions between mutant genes and genotypic back ground cannot be predicted. Therefore, mutants with valuable traits should be crossed with many varieties and strains in order to discern positive and negative interactions. In this way, genotypes can be selected in which the mutant gene is able to express its action without showing negative by-effects. This procedure has been used for about 10 years by combining the methods of mutation and crossbreeding. Mutation breeding is predominantly used in annual diploid and allo polyploid self-fertilizing crops, while it causes much more difficulties in cross-pollinating species.
