Nectaries and Nectar

About this book

Nectar is the most important reward offered by plants to pollinating animals. This book is a modern and interdisciplinary text on nectar and nectaries, prompted by the expansion of knowledge, especially in the more ecological and now molecular fields, and the strong recent interest in pollination biology. The topics covered vary widely: they include historical aspects, the structure and ultrastructure of nectaries and relationships to plant systematics, the dynamics of nectar secretion, nectar chemistry and the molecular biology of defence proteins, adaptations to insect and vertebrate nectar consumers and consequences for pollination ecology, and broad-scale studies of nectar resources at the community level.

Contents

Contributing Authors. Preface. 1. Introduction; E. Pacini, S.W. Nicolson. 1.1 Evolutionary origins. 1.2 Secretions analogous to nectar. 1.3 Floral and extrafloral nectarines. 1.4 Nectar components. 1.5 Organization of this volume. 2. A Systematic Survey of Floral Nectaries; G. Bernardello. 2.1 Introduction. 2.2 Nectaries in gymnosperms. 2.3 Nectaries in angiosperms. 2.3.1 Diversity. 2.3.1.1 Nectar presentation. 2.3.1.2 Structure. 2.3.1.3 Fate. 2.3.1.4 Symmetry. 2.3.1.5 Number. 2.3.1.6 Colour. 2.3.2 Factors influencing nectary diversity. 2.3.3 Basic types of floral nectarines. 2.3.4 Nectariferous spurs. 2.3.5 Patterns of variability in nectarines. 2.3.5.1 Asteraceae. 2.3.5.2 Brassicaceae. 2.3.5.3 Cucurbitaceae. 2.3.5.4 Euphorbiaceae. 2.3.5.5 Ranunculaceae. 2.3.5.6 Solanaceae. 2.3.6 Nectaries and deceit pollination. 2.3.6.1 Apocynaceae. 2.3.6.2 Bignoniaceae. 2.3.6.3 Orchidaceae. 2.3.7 Relictual nectarines in anemophilous species. 2.3.8 Distribution of nectary types. 2.3.8.1 Early-branching lineages. 2.3.8.2 Magnoliids. 2.3.8.3 Early-branching monocots. 2.3.8.4 Monocots. 2.3.8.5 Commelinids. 2.3.8.6 Ceratophyllales. 2.3.8.7 Eudicots. 2.3.8.8 Core Eudicots. 2.3.8.9 Rosids. 2.3.8.10 Eurosids I. 2.3.8.11 Eurosids II. 2.3.8.12 Asterids. 2.3.8.13 Euasterids I. 2.3.8.14 Euasterids II. 2.3.9 Evolutionary trends. 3. Nectary Structure and Ultrastructure; M. Nepi. 3.1 Introduction. 3.2 Nectary structure and ultrastructure. 3.2.1 Epidermis. 3.2.1.1 Secretory trichomes. 3.2.1.2 Nectary-modified stomata. 3.2.2 Nectary parenchyma. 3.2.2.1 Patterns of plastid development in nectary parenchyma cells. 3.2.3 Subnectary parenchyma. 3.2.4 Nectary vasculature. 3.3 Gynopleural (septal) nectarines. 3.4 Extrafloral nectarines. 3.5 Nectary histochemistry. 4. Nectar Production and Presentation; E. Pacini, M. Nepi. 4.1 Introduction. 4.2 Nectar secretion mechanism and models of nectary function. 4.3 Dynamics of nectar components. 4.3.1 Nectar reabsortion: resource recovery and homeostasis. 4.3.2 Nectar standing crop. 4.4 The source of nectar components. 4.5 Ecophysiological significance of parenchyma plastids. 4.6 Nectar presentation. 4.6.1 Floral nectarines. 4.6.2 Extrafloral nectarines. 4.7 Fate of nectar and nectarines. 4.8 Variability of nectar characteristics. 4.8.1 Environmental variables. 4.8.2 Intraspecies variability. 4.8.3 Interpopulation differences. 4.8.4 Variability and experimental design. 5. Nectar Chemistry; S.W. Nicolson, R.W. Thornburg. 5.1 Introduction. 5.2 Water. 5.2.1 Nectar concentration. 5.2.2 Chemical and microclimatic influences on nectar concentration. 5.2.3 Viscosity and feeding rates. 5.3 Sugars. 5.3.1 Constancy of sugar composition within species. 5.3.2 The use of sugar ratios can be misleading. 5.3.3 Is sugar composition determined by floral visitors or common ancestry? 5.4 Inorganic ions. 5.5 Amino acids. 5.5.1 Non-protein amino acids. 5.5.2 Nectar amino acids are under the control of environmental factors. 5.5.3 Contribution of amino acids to the taste of nectar. 5.6 Proteins. 5.6.1 Proteins in leek nectar. 5.6.2 Nectar redox cycle. 5.7 Other nectar constituents. 5.7.1 Lipids. 5.7.2 Organic acids. 5.7.3 Phenolics. 5.7.4 Alkaloids. 5.7.5 Terpenoids. 5.8 Conclusion. 6. Molecular Biology of the Nicotiana Floral Nectary; R.W. Thornburg. 6.1 Introduction. 6.2 The ornamental tobacco nectary. 6.3 Developmental processes. 6.3.1 Origin of the floral nectary. 6.3.2 Conversion of chloroplasts into chromoplasts. 6.3.3 Filling of the nectary. 6.4 Protection of the gynoecium. 6.5 Gene expression. 6.5.1 Macroarray analysis indentifies defence genes. 6.5.1.1 Role of hydrogen peroxide in plant stress and defence. 6.5.1.2 Role of ascorbate in plant stress and defence. 6.5.2 EST analysis. 6.5.3 Nectary-specific gene expression. 6.6 Nectary molecular biology in other species. 6.6.1 Other nectary-expressed genes. 6.6.2 Metabolism and nectar secretion. 6.6.3 Hormones and nectar production. 6.6.4 CO2 and nectar. 7. Nectar Consumers; S.W. Nicolson. 7.1 Introduction. 7.2 Not all floral nectar drinkers are pollinators. 7.2.1 Generalisation and specialization in pollination systems. 7.2.2 Nectar robbing and nectar theft. 7.3 Insect nectar consumers. 7.3.1 Coleoptera. 7.3.2 Diptera. 7.3.3 Lepidoptera. 7.3.4 Hymenoptera. 7.3.4.1 Wasps. 7.3.4.2 Bees. 7.3.4.3 Ants. 7.4 Vertebrate nectar consumers. 7.4.1 Lizards. 7.4.2 Birds. 7.4.3 Bats. 7.4.4 Other mammals. 7.5 What happens to nectar during pollinator shifts? 7.6 Conclusion. 8. Ecological and Evolutionary Aspects of Floral Nectars in Mediterranean Habitats; T. Petanidou. 8.1 Nectar secretion in Mediterranean habitats. 8.2 Characteristics of Mediterranean nectars. 8.2.1 Nectar constituents of Mediterranean nectars. 8.2.1.1 Sugars. 8.2.1.2 Amino acids. 8.2.1.3 Minerals in floral nectars. 8.2.1.4 Secondary compounds. 8.2.1.5 Nectar viscosity. 8.2.2 Issues of nectar quantity and quality. 8.2.3 Plant Species with no nectar.8.3 Factors shaping nectar secretion and other characteristics. 8.3.1 Temperature. 8.3.2 Humidity. 8.3.3 Light intensity. 8.3.4 Water stress. 8.3.5 Nutrient stress. 8.3.6 Ecological succession. 8.4 Matching nectars and flower types. 8.5 Nectar and the pollinator interface. 8.5.1 Relating consumers to deep-flower nectars. 8.5.2 Nectar sugars and pollinators. 8.5.3 Nectar amino acids and pollinators. 8.5.4 Nectar minerals and pollinators. 8.5.5 Nectar secondary compounds and pollinators. 8.5.6 Floral nectar, floral diversity, and bee diversity. 8.5.7 What types of nectars do pollinators prefer? 8.6 Nectar management of Mediterranean habitats. 8.6.1 Introduced and invasive plants: effects on wild flowers and bees. 8.6.2 Invasive bees: beekeeping, bumblebee management, and wild bee conservation. Index to Scientific Names. Subject Index.

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Biography

Sue Nicolson is a New Zealander who obtained her PhD in insect physiology from the University of Cambridge. She is a professor in the Department of Zoology and Entomology at the University of Pretoria, South Africa, and her main research interest is in ecophysiological aspects of nectar feeding in insects and birds. Massimo Nepi was awarded a PhD in agricultural biology in 1995. He is currently employed as researcher at the Department of Environmental Sciences of the University of Siena, where he carries out studies concerning the reproductive biology of angiosperms. In recent years his main research interest has been nectar and nectary biology. Ettore Pacini graduated in botany in 1967 at the University of Siena, where he is still engaged as full professor of Botany. His main research interest has been higher plant reproduction, first from a cytological point of view and also from an ecological point of view during the last two decades. Recently he became a member of the prestigious Accademia dei Lincei, the first Scientific Academy, founded in 1604.