Plant Breeding

Jack Brown, Full Professor, Plant Breeding & Genetics, University of Idaho, USA.  HNC Mathematics & Statistics, Napier College, Edinburgh, Scotland; MSc and PhD at St Andrews University, St Andrews, Scotland.  Professor Brown has over 40 years of experience working as a plant breeder in the public and private sector and has developed and released cultivars of barley, potato, canola, mustard and wheat.  Professor Brown currently teaches upper division and graduate classes in plant breeding, genetics, and field crop production. Peter Caligari, Full Professor, University of Talca, Chile.  BSc, PhD and DSc at University of Birmingham, UK.  Professor Caligari has over 40 years of research experience in, and application of, genetics and plant breeding in a range of crops including potatoes, cashew nuts, oil palm, lupins, strawberries and blueberries, and extensive teaching experience including plant breeding and genetics at the graduate and post-graduate level. Hugo Campos, Fellow, Monsanto, Chile. BSc at Universidad Austral de Chile, PhD at the John Innes Centre, UK, MBA at Universidad del Desarrollo, Chile. Dr Campos has over 24 years of experience in plant biotechnology, crop breeding and product development in industry, academia and international agricultural development.

• Preface xi About the companion website xiii1 Introduction 11.1 Requirements of plant breeders 11.2 Evolution of crop species 41.2.1 Why did hunter-gatherers become farmers? 41.2.2 What crops were involved? And when did they arise? 51.3 Natural and human selection 81.4 Contribution of modern plant breeders 8Think questions 112 Modes of Reproduction and Types of Cultivar 132.1 Introduction 132.2 Modes of reproduction 152.2.1 Sexual reproduction 152.2.2 Asexual reproduction 162.3 Types of cultivar 172.3.1 Pure-line cultivars 172.3.2 Open-pollinated cultivars 172.3.3 Hybrid cultivars 182.3.4 Clonal cultivars 182.3.5 Synthetic cultivars 182.3.6 Multiline cultivars 182.3.7 Composite-cross cultivars 192.4 Annuals and perennials 192.5 Reproductive sterility 19Think questions 193 Breeding Objectives 213.1 Introduction 213.2 People, politics and economic criteria 223.3 Grower profitability 253.3.1 Increasing harvestable yield 263.3.2 Selection for yield increase 273.4 Increasing end-use quality 283.4.1 Testing for end-use quality 303.5 Increasing pest and disease resistance 313.6 Types of plant resistance 343.7 Mechanisms for disease resistance 353.8 Testing plant resistance 363.9 Conclusions 38Think questions 384 Breeding Schemes 404.1 Introduction 404.2 Development of pure-line cultivars 404.2.1 Homozygosity 414.2.2 Breeding schemes for pure-line cultivars 434.2.3 Number of segregating families and selections 464.2.4 Seed increases for cultivar release 464.3 Developing multiline cultivars 474.3.1 Backcrossing 484.4 Development of open-pollinated population cultivars 494.4.1 Breeding schemes for open-pollinating population cultivars 494.4.2 Backcrossing in open-pollinated population cultivar development 514.5 Developing synthetic cultivars 514.5.1 Seed production of a synthetic cultivar 534.6 Developing hybrid cultivars 534.6.1 Heterosis 554.6.2 Types of hybrid 584.6.3 Breeding system for F1 hybrid cultivars 584.6.4 Backcrossing in hybrid cultivar development 594.6.5 Hybrid seed production and cultivar release 604.7 Development of clonal cultivars 614.7.1 Outline of a potato breeding scheme 614.7.2 Time to develop clonal cultivars 624.7.3 Sexual reproduction in clonal crops 634.7.4 Maintaining disease-free parental lines and breeding selections 644.7.5 Seed increase of clonal cultivars 644.8 Developing apomictic cultivars 644.9 Summary 65Think questions 655 Genetics and Plant Breeding 685.1 Introduction 685.2 Qualitative genetics 685.2.1 Genotype/phenotype relationships 705.2.2 Segregation of qualitative genes in diploid species 705.2.3 Qualitative loci linkage 725.2.4 Pleiotropy 765.2.5 Epistasis 765.2.6 Qualitative inheritance in tetraploid species 775.2.7 The chi-square test 795.2.8 Family size necessary in qualitative genetic studies 815.3 Quantitative genetics 825.3.1 The basis of continuous variation 825.3.2 Describing continuous variation 835.3.3 Relating quantitative genetics and the normal distribution 865.3.4 Quantitative genetics models 875.3.5 Testing the models 905.3.6 Quantitative trait loci 97Think questions 1016 Predictions 1046.1 Introduction 1046.1.1 Genotype × environment interactions 1046.1.2 Genetically based predictions 1056.2 Heritability 1066.2.1 Broad-sense heritability 1076.2.2 Narrow-sense heritability 1086.2.3 Heritability from offspring – parent regression 1096.3 Diallel crossing designs 1106.3.1 Griffing’s analysis 1116.3.2 Hayman and Jinks’ analysis 1166.4 Cross prediction 119Think questions 1207 Selection 1257.1 Introduction 1257.2 What to select and when to select 1257.2.1 Qualitative trait selection 1267.2.2 Quantitative trait selection 1267.2.3 Positive and negative selection 1267.3 Response to selection 1277.3.1 Association between traits or years 1297.3.2 Heritability and its limitations 1307.3.3 Methods of selection 1317.3.4 Errors in selection 1337.4 Applied selection 1367.4.1 Number of genotypes in initial populations 1367.4.2 Early generation selection 1397.4.3 Intermediate generation selection 1417.4.4 Advanced generation selection 1437.4.5 Analysis of location trials 1467.5 Cross prediction 1517.5.1 Univariate cross prediction 1527.5.2 Multivariate cross prediction 1577.6 Parental selection 1597.6.1 Phenotypic evaluation 1607.6.2 Genotypic evaluation 1607.6.3 Parental combinations 1617.6.4 Germplasm collections 162Think questions 1638 Broadening the Genetic Basis 1688.1 Induced mutations 1688.1.1 Methods of increasing the frequency of mutation 1698.1.2 Types of mutation 1698.1.3 Plant parts to be treated 1708.1.4 Dose rates 1708.1.5 Dangers of using mutagens 1718.1.6 Impact of mutation breeding 1718.1.7 Practical applications 1728.2 Interspecific and intergeneric hybridization 1748.2.1 Characters introduced to crops from wild related species 1748.2.2 Factors involved in interspecific or intergeneric hybridization 1758.2.3 Post-fertilization 1768.2.4 Hybrid sterility 1768.2.5 Backcrossing 1768.2.6 Increasing genetic diversity 1778.2.7 Creating new species 1778.3 Plant genetic transformation 1778.3.1 A glimpse at the genetic transformation of plants 1798.3.2 Some applications of genetic engineering to plant breeding 1818.3.3 Cautions and related issues 183Think questions 1839 Contemporary Approaches in Plant Breeding 1859.1 Introduction 1859.2 Tissue culture 1859.2.1 Doubled haploids 1859.2.2 Some potential issues 1869.2.3 In vitro multiplication 1889.3 Molecular markers in plant breeding 1889.3.1 Theory of using markers 1889.3.2 Types of marker systems 1909.3.3 Molecular markers 1919.3.4 Uses of molecular markers in breeding programmes 1929.3.5 Issues with markers 1959.3.6 The increasing availability of genome sequences 195Think questions 19710 Practical Considerations 19810.1 Introduction 19810.2 Experimental design 19810.2.1 Unreplicated designs 19910.2.2 Randomized designs 20110.2.3 The increasing role of linear mixed model approaches to analyse breeding data 20310.3 Greenhouse management 20410.3.1 Artificial hybridization 20410.3.2 Seed and generation increases 20610.3.3 Evaluation of breeding lines 20610.3.4 Environmental control 20710.3.5 Disease control 20710.3.6 Economics 20810.3.7 Experimental design in the glasshouse 20910.4 Field plot techniques 20910.4.1 Choice of land 20910.4.2 Plot size and replication 21110.4.3 Guard rows and discard rows 21210.4.4 Machinery 21210.5 Use of computers in plant breeding 21410.5.1 Data storage and retrieval 21510.5.2 Field plan design 21710.5.3 Clerical operations 21710.5.4 Data collection 21710.5.5 Data analysis 21810.5.6 Selection 21910.5.7 Data transfer 22010.5.8 Statistical consultation 22010.5.9 Ease of use 22010.6 Release of new cultivars 22010.6.1 Information needed prior to cultivar release 22110.6.2 Value in release 22110.6.3 Cultivar names 222Think questions 22211 Current Developments in Plant Breeding 22311.1 Intellectual property and ownership issues 22311.1.1 Patents 22311.2 The impact of biotechnology 22511.3 The regulation of genetically modified plants 22711.4 Plant breeding as a career 228Further Reading 229Suggested Answers to Think Questions 230Index 271

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