Plant Tropisms

About this book

Tropisms, the defined vectorial stimuli, such as gravity, light, touch, humidity gradients, ions, oxygen, and temperature, which provide guidance for plant organ growth, is a rapidly growing and changing field. The last few years have witnessed a true renaissance in the analysis of tropisms. As such the conception of tropisms has changed from being seen as a group of simple laboratory curiosities to their recognition as important tools/phenotypes with which to decipher basic cell biological processes that are essential to plant growth and development.

Plant Tropisms will provide a comprehensive, yet integrated volume of the current state of knowledge on the molecular and cell biological processes that govern plant tropisms.

Contents

ContributorsPreface 1. Mechanisms of Gravity Perception in Higher Plants: Aline H. Valster and Elison B. Blancaflor1.1 Introduction1.2 Identification and characterization of gravity perception sites in plant organs1.2.1 Roots1.2.2 Hypocotyls and inflorescence stems (dicotyledons)1.2.3 Cereal pulvini (monocotyledons)1.3 The Starch-statolith hypothesis1.3.1 A variety of plant organs utilize sedimenting amyloplasts to sense gravity1.3.2 Amyloplast sedimentation is influenced by the environment and developmental stage of the plant1.4 The gravitational pressure model for gravity sensing 1.5 The cytoskeleton in gravity perception1.6 Concluding remarks and future prospects 1.7 Acknowledgment1.8 Literature Cited 2. Signal Transduction in Gravitropism: Benjamin R. Harrison, Miyo T. Morita, Patrick H. Masson and Masao Tasaka2.1 Introduction2.2 Gravity signal transduction in roots and above-ground organs2.2.1 Do mechano-sensitive ion channels function as gravity receptors?2.2.2 Inositol 1,4,5 trisphosphate seems to function in gravity signal transduction2.2.3 Do pH changes contribute to gravity signal transduction?2.2.4 Proteins implicated in gravity signal transduction2.2.5 Global '-omic' approaches to the study of root gravitropism2.2.6 Re-localization of auxin transport facilitators or activity regulation?2.2.7 Could cytokinin also contribute to the gravitropic signal?2.3 Gravity signal transduction in organs that do not grow vertically2.4 Acknowledgments2.5 Cited Literature 3. Auxin Transport and the Integration of Gravitropic Growth: Gloria K. Muday and Abidur Rahman3.1 Introduction to auxins3.2 Auxin transport and its role in plant gravity response3.3 Approaches to Identify Proteins that Mediate IAA Efflux3.4 Proteins that Mediate IAA Efflux3.5 IAA influx carriers and their role in gravitropism3.6 Regulation of IAA efflux protein location and activity during gravity response3.6.1 Mechanisms that may control localization of IAA efflux carriers3.6.2 Regulation of IAA efflux by synthesis and degradation of efflux carriers3.6.3 Regulation of auxin transport by reversible protein phosphorylation3.6.4 Regulation of auxin transport by flavonoids3.6.5 Regulation of auxin transport by other signaling pathways3.6.6 Regulation of gravity response by ethylene3.7 Overview of the mechanisms of auxin induced growth3.8 Conclusions3.9 Acknowledgements3.10 Cited Literature 4. Phototropism and its Relationship to Gravitropism: Jack L. Mullen and John Z. Kiss 4.1 Phototropism: General Description and Distribution4.2 Light Perception4.3 Signal Transduction and Growth Response4.4 Interactions with Gravitropism4.5 Importance to Plant Form and Function4.6 Conclusions and outlook4.7 References 5. Touch Sensing and Thigmotropism: Gabriele B. Monshausen, Sarah J. Swanson and Simon Gilroy5.1 Introduction5.2 Plant mechanoresponses5.2.1 Specialized touch responses5.2.2 Thigmomorphogenesis and thigmotropism5.3 General principles of touch perception5.3.1 Gating through membrane tension: the mechanoreceptor for hypoosmotic stress in bacteria, MscL5.3.2 Gating through tethers: the mechanoreceptor for gentle touch in Caenorhabditis elegans5.3.3 Evidence for mechanically gated ion channels in plants5.4 Signal transduction in Touch & Gravity Perception5.4.1 Ionic signaling5.4.2 Ca2+ signaling in the touch and gravity response5.5 Insights from transcriptional profiling5.6 Interaction of touch and gravity signaling/response5.7 Conclusion and Perspectives5.8 Acknowledgements5.9 Cited Literature 6. Other Tropisms and their Relationship to Gravitropism: Gladys I. Cassab6.1 Introduction6.2 Hydrotropism6.2.1 Early studies of hydrotoprism6.2.2 Genetic analysis of hydrotropism6.2.3 Perception of moisture gradients and gravity stimuli by the root cap and the curvature response6.2.4 ABA and the hydrotropic response6.2.5 Future experiments6.3 Electrotropism6.4 Chemotropism6.5 Thermotropism and oxytropism6.6 Traumatropism6.7 Overview6.8 Acknowledgments6.9 Literature cited 7. Single-Cell Gravitropism and Gravitaxis: Markus Braun and Ruth HemmersbachIntroduction7.1 Definitions of responses to environmental stimuli that optimize the ecological fitness of single-cell organisms7.2 Occurrence and significance of gravitaxis in single-cell systems7.3 Significance of gravitropism in single-cell systems7.4 What makes a cell a biological gravity sensor?7.5 Gravity susception - the initial physical step of gravity sensing 7.6 Susception in the statolith-based systems of Chara 7.7 Susception in the statolith-based system Loxodes 7.8 Susception in the protoplast-based systems of Euglena and Paramecium 7.9 Graviperception in the statolith-based systems of Chara7.10 Graviperception in the statolith-based system Loxodes7.11 Graviperception in the protoplast-based systems Paramecium and Euglena7.12 Signal transduction pathways and graviresponse mechanisms in the statolith-based systems of Chara7.13 Signal transduction pathways and graviresponse mechanisms in Euglena and Paramecium7.14 Conclusions7.15 Acknowledgements7.18 Cited Literature 8. Space-Based Research on Plant Tropisms: Melanie J. Correll and John Z. Kiss8.1 Introduction - the variety of plant movements8.2 The microgravity environment8.3 Ground-based studies: mitigating the effects of gravity8.4 Gravitropism8.4.1 Gravitropism: gravity perception8.4.2 Gravitropism: signal transduction8.4.3 Gravitropism: the curving response8.5 Phototropism8.6 Hydrotropism, autotropism and oxytropism8.7 Studies of other plant movements in microgravity 8.8 Spaceflight hardware used to study tropisms8.9 Future outlook and prospects8.10 Cited Literature 9. Plan(t)s for Space Exploration: Christopher S. Brown, Heike Winter Sederoff, Eric Davies, Robert J. Ferl, and Bratislav StankovicIntroduction9.1 Human missions to space9.2 Life support9.3 Genomics and space exploration9.4 Nanotechnology9.5 Sensors, biosensors and intelligent machines9.6 Plan(t)s for space exploration9.7 Imagine...9.8 Literature cited

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Biography

Simon Gilroy, Ph.D., is Associate Professor of Biology at Pennsylvania State University. Patrick Masson, Ph.D., is Professor of Genetics at the University of Wisconsin.