1;Chapter 1: Developmental Biology of Somatic Embryogenesis;22 1.1;Introduction;22 1.2;Basic Requirements for In Vitro SE;23 1.3;Explant and Stem Cell Biology;24 1.3.1;Genotype;24 1.3.2;Explant Cells;25 1.4;Earliest Event in Embryogenesis-Asymmetric Cell Division;27 1.4.1;Cell Wall in Establishment of Polarity, Division Asymmetry and Cell Fate;27 1.4.2;Division Asymmetry in the Initiation of SE;29 1.4.3;Asymmetric Division and the Suspensor in SE;29 1.5;Stress Component in the Initiation of SE;30 1.5.1;Reactive Oxygen Species;30 1.5.2;Stress-Related Hormone Signalling;31 1.6;Hormones and the Initiation of SE;32 1.7;Induction of SE by Over-Expression of Leafy Cotyledon Transcription Factors and Their Relationship to SE Induction and Repress;33 1.8;ABA, Stress and GA;35 1.9;Soluble Signals and Cell-Cell Interactions that Promote SE in Suspension Cultures;35 1.9.1;Secreted Proteins that Influence SE;35 1.9.2;AGP Signalling in SE: Mechanisms and Interactions Between Signalling Pathways;36 1.9.3;Cell-Cell Interaction and Relevance to SE in Suspension Cultures;37 1.10;Development Program After SE Induction;38 1.11;Concluding Remarks and a Model Based on Studies in Medicago truncatula;38 1.12;SE and Biotechnology;39 1.13;References;40 2;Chapter 2: Microspore Embryogenesis;46 2.1;Introduction;46 2.2;Discovery of the Production of Haploids by Anther Cultureanther culture;48 2.3;Strategies for the Induction of Microspore Embryogenesis;48 2.4;Influence of Different Factors in Microspore Embryogenesis;49 2.4.1;Genotype;49 2.4.2;Donor Plant Physiology;50 2.4.3;Stage of Pollen Development;50 2.4.4;Pre-treatments;51 2.4.5;Culture Conditions;51 2.4.6;Composition of the Medium;52 2.5;Cellular and Molecular Events Associated with Microspore Embryogenesis;53 2.5.1;Embryogenic Induction;53 2.5.2;Early Embryogenic Divisions;56 2.5.3;Development of Embryo Pattern;57 2.5.4;Plant Formation and Diploidization;58 2.6;Conclusions;58 2.7;References;59 3;Chapter 3: Stress and Somaclonal Variation;64 3.1;Introduction;64 3.2;Stress Responses in Plants;65 3.2.1;Short-Term Responses;65 3.2.2;Long-Term Responses;66 3.2.3;Modifications Induced by Stress Could be Inheritable;68 3.3;Tissue Culture Imposes a Stress to Cultivated In Vitro Cells;69 3.4;Cultured Cellscultured cells and Regenerated Plantsregenerated plants Show Variations;71 3.4.1;Heritable Changes Versus Non-Heritable Changes;73 3.4.2;Genetic Versus Epigenetic Changes;74 3.4.3;Variation Promoted by Tissue Culture is Not Randomly Distributed in the Genome;76 3.4.4;Are New Alleles Originated by In Vitro Stress Already Present in Other Plants of In Vivo Populations?;77 3.5;Concluding Remarks;77 3.6;References;77 4;Chapter 4: Photosynthate Partitioning;85 4.1;Introduction;85 4.2;Source and Sink;87 4.3;Sugars as Signalling Molecules;87 4.4;Key Metabolic Regulators;88 4.4.1;SNF1-Related Protein Kinase 1 (SnRK1);88 4.4.2;Hexokinase;92 4.4.3;The Trehalose Pathway;92 4.5;Applications in Biotechnology;93 4.6;Concluding Remarks;97 4.7;References;98 5;Chapter 5: Molecular Physiology of Seed Maturation and Seed Storage ProteinSeed Storage Protein Biosynthesis;101 5.1;Introduction;101 5.2;Seed MaturationSeed maturation;102 5.3;SucroseSucrose as a Maturation Signal;103 5.4;Synthesis and Deposition of Storage Proteins in Crop Seedscrop seeds;104 5.5;Storage Proteins in Cereals;105 5.5.1;Storage Proteins in the Different Grain Parts;105 5.5.2;Transcriptional RegulationTranscriptional regulation of Arabidopsis Seed MaturationArabidopsis seed maturation;107 5.5.3;Transcriptional Regulation of Arabidopsis Seed Maturation-a Model Also for Cereal Seeds?;107 5.5.4;Unravelling Transcriptional Regulation by Co-Expression Analysisco-expression analysis;108 5.5.5;DNA MethylationDNA methylation and Storage Protein Gene Expression in the Barley Endosperm;110 5.6;Metabolic ControlMetabolic control of Seed Storage Protein Synthesis;111 5.6.1;Nitrogen Availability and Signalling;111 5.6.1.1;Nitrogen TransportNitrogen transport into