What are plant growth regulators? In the title, and throughout the text, we have adopted this expression to describe a population of endogenous molecules and synthetic compounds of similar structure that are be­ lieved to play important roles in the regulation of plant differentiation and development. For many years, plant scientists have endeavoured to understand the nature and action of plant growth regulators and, as a result, an awesome quantity of written material now exists describing these chemicals and their effects. In this book we have aimed to distil this wealth of information into a more digestible form, and in particular we have focused our attention on a critical appraisal of the literature. The past few years have witnessed a change of emphasis in plant growth regulator research, which has been fuelled by powerful new techniques in molecular and cell biology. Today we can do more than just apply a plant growth regulator and quantify its effects; we have reached an exciting crossroads where plant scientists, molecular bio­ logists and chemists can pool their expertise and apply it to the out­ standing problems in this area. The combination of these three disciplines within the book is clear evidence of this. In keeping with a volume of this size, we have assumed that the reader has a sound knowledge of plant physiology and biochemistry. However, wherever possible, we have highlighted useful reviews which provide background information, along with recent publications that have contributed significantly to the literature.

Inhalt

1 Introduction - the challenge of PGR research.- 2 Biosynthesis and metabolism - more than making and breaking.- 2.1 Auxins.- 2.1.1 Background and biosynthesis.- 2.1.2 Metabolism.- 2.1.3 Biosynthesis of IAA in Agrobacterium tumefaciens tumours.- 2.2 Gibberellins.- 2.2.1 Background and biosynthesis.- 2.2.2 Metabolism.- 2.3 Cytokinins.- 2.3.1 Background and biosynthesis.- 2.3.2 Metabolism.- 2.4 Abscisic acid.- 2.4.1 Background and biosynthesis.- 2.4.2 Metabolism.- 2.5 Ethylene.- 2.5.1 Background and biosynthesis.- 2.5.2 Metabolism.- 2.6 Polyamines.- 2.7 More than making and breaking.- 3 Extraction, identification and quantification - the state of the art.- 3.1 Extraction.- 3.2 Purification.- 3.3 Identification and quantification.- 3.3.1 Bioassays.- 3.3.2 Chemical methods.- 3.3.3 Immunological methods.- 3.3.4 Gas chromatography.- 3.3.5 Gas chromatography-mass spectrometry.- 3.3.6 High performance liquid chromatography.- 3.4 The state of the art.- 4 Hormones and the concept of sensitivity - a rational approach.- 4.1 The hormone concept.- 4.1.1 Sites and regulation of biosynthesis.- 4.1.2 Transport and its regulation.- 4.1.3 Target cells.- 4.2 The concept of sensitivity.- 4.3 Hormones and the concept of sensitivity - a rational approach.- 5 Cellular differentiation and morphogenesis.- 5.1 Juvenility.- 5.2 Flowering.- 5.2.1 Photoperiodism.- 5.2.2 Vernalization.- 5.3 Sex expression.- 5.4 Vascular differentiation.- 5.5 Morphogenesis.- 5.6 Conclusions.- 6 Seed development, dormancy and germination.- 6.1 Seed development.- 6.2 Dormancy.- 6.3 Germination.- 6.4 Mobilization of storage reserves.- 6.5 Conclusions.- 7 Root and shoot development.- 7.1 Growth.- 7.2 Tropisms.- 7.2.1 Gravitropism.- 7.2.2 Phototropism.- 7.3 Apical dominance.- 7.4 Bud dormancy and tuberization.- 7.5 Conclusions.- 8 Leaf, flower and fruit development.- 8.1 Growth.- 8.2 Regulation of stomatal aperture.- 8.3 Epinasty and hyponasty.- 8.4 Ripening.- 8.5 Senescence.- 8.6 Abscission.- 8.7 Conclusions.- 9 Receptors - sites of perception or deception?.- 9.1 Binding studies.- 9.1.1 Theory.- 9.1.2 Practice.- 9.2 Binding sites for PGRs.- 9.2.1 Auxins.- 9.2.2 Gibberellins.- 9.2.3 Abscisicacid.- 9.2.4 Cytokinins.- 9.2.5 Ethylene.- 9.3 Sites of perception or deception?.- 10 Mechanisms of action - towards a molecular understanding.- 10.1 Regulation of ion movement.- 10.2 Regulation of gene expression.- 10.2.1 Auxins.- 10.2.2 Gibberellins.- 10.2.3 Abscisicacid.- 10.2.4 Ethylene.- 10.3 Second messengers.- 10.3.1 Calcium.- 10.3.2 Calmodulin.- 10.3.3 cAMP.- 10.3.4 Protein phosphorylation.- 10.3.5 Inositol phospholipids.- 10.4 Towards a molecular understanding.- 11 Commercial applications for PGRs - thought for food?.- 11.1 Auxins and related compounds.- 11.2 Gibberellins and growth retardants.- 11.3 Cytokinins and related compounds.- 11.4 Abscisic acid and anti-transpirants.- 11.5 Ethylene-generating or suppressing compounds.- 11.6 Thought for food - food for thought.- References and further reading.