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. <i>Plant Tropisms</i> will provide a comprehensive, yet integrated volume of the current state of knowledge on the molecular and cell biological processes that govern plant tropisms.
Contributors. <p>Preface.</p> <p>1. Mechanisms of Gravity Perception in Higher Plants: Aline H. Valster and Elison B. Blancaflor.</p> <p>1.1 Introduction.</p> <p>1.2 Identification and characterization of gravity perception sites in plant organs.</p> <p>1.2.1 Roots.</p> <p>1.2.2 Hypocotyls and inflorescence stems (dicotyledons).</p> <p>1.2.3 Cereal pulvini (monocotyledons).</p> <p>1.3 The Starch-statolith hypothesis.</p> <p>1.3.1 A variety of plant organs utilize sedimenting amyloplasts to sense gravity.</p> <p>1.3.2 Amyloplast sedimentation is influenced by the environment and developmental stage of the plant.</p> <p>1.4 The gravitational pressure model for gravity sensing.</p> <p>1.5 The cytoskeleton in gravity perception.</p> <p>1.6 Concluding remarks and future prospects.</p> <p>1.7 Acknowledgment.</p> <p>1.8 Literature Cited.</p> <p>2. Signal Transduction in Gravitropism: Benjamin R. Harrison, Miyo T. Morita, Patrick H. Masson and Masao Tasaka.</p> <p>2.1 Introduction.</p> <p>2.2 Gravity signal transduction in roots and above-ground organs.</p> <p>2.2.1 Do mechano-sensitive ion channels function as gravity receptors?.</p> <p>2.2.2 Inositol 1,4,5 trisphosphate seems to function in gravity signal transduction.</p> <p>2.2.3 Do pH changes contribute to gravity signal transduction?.</p> <p>2.2.4 Proteins implicated in gravity signal transduction.</p> <p>2.2.5 Global ‘-omic’ approaches to the study of root gravitropism.</p> <p>2.2.6 Re-localization of auxin transport facilitators or activity regulation?.</p> <p>2.2.7 Could cytokinin also contribute to the gravitropic signal?.</p> <p>2.3 Gravity signal transduction in organs that do not grow vertically.</p> <p>2.4 Acknowledgments.</p> <p>2.5 Cited Literature.</p> <p>3. Auxin Transport and the Integration of Gravitropic Growth: Gloria K. Muday and Abidur Rahman.</p> <p>3.1 Introduction to auxins.</p> <p>3.2 Auxin transport and its role in plant gravity response.</p> <p>3.3 Approaches to Identify Proteins that Mediate IAA Efflux.</p> <p>3.4 Proteins that Mediate IAA Efflux.</p> <p>3.5 IAA influx carriers and their role in gravitropism.</p> <p>3.6 Regulation of IAA efflux protein location and activity during gravity response.</p> <p>3.6.1 Mechanisms that may control localization of IAA efflux carriers.</p> <p>3.6.2 Regulation of IAA efflux by synthesis and degradation of efflux carriers.</p> <p>3.6.3 Regulation of auxin transport by reversible protein phosphorylation.</p> <p>3.6.4 Regulation of auxin transport by flavonoids.</p> <p>3.6.5 Regulation of auxin transport by other signaling pathways.</p> <p>3.6.6 Regulation of gravity response by ethylene.</p> <p>3.7 Overview of the mechanisms of auxin induced growth.</p> <p>3.8 Conclusions.</p> <p>3.9 Acknowledgements.</p> <p>3.10 Cited Literature.</p> <p>4. Phototropism and its Relationship to Gravitropism: Jack L. Mullen and John Z. Kiss.</p> <p>4.1 Phototropism: General Description and Distribution.</p> <p>4.2 Light Perception.</p> <p>4.3 Signal Transduction and Growth Response.</p> <p>4.4 Interactions with Gravitropism.</p> <p>4.5 Importance to Plant Form and Function.</p> <p>4.6 Conclusions and outlook.</p> <p>4.7 References.</p> <p>5. Touch Sensing and Thigmotropism: Gabriele B. Monshausen, Sarah J. Swanson and Simon Gilroy.</p> <p>5.1 Introduction.</p> <p>5.2 Plant mechanoresponses.</p> <p>5.2.1 Specialized touch responses.</p> <p>5.2.2 Thigmomorphogenesis and thigmotropism.</p> <p>5.3 General principles of touch perception.</p> <p>5.3.1 Gating through membrane tension: the mechanoreceptor for hypoosmotic stress in bacteria, MscL.</p> <p>5.3.2 Gating through tethers: the mechanoreceptor for gentle touch in Caenorhabditis elegans.</p> <p>5.3.3 Evidence for mechanically gated ion channels in plants.</p> <p>5.4 Signal transduction in Touch & Gravity Perception.</p> <p>5.4.1 Ionic signaling.</p> <p>5.4.2 Ca2+ signaling in the touch and gravity response.</p> <p>5.5 Insights from transcriptional profiling.</p> <p>5.6 Interaction of touch and gravity signaling/response.</p> <p>5.7 Conclusion and Perspectives.</p> <p>5.8 Acknowledgements.</p> <p>5.9 Cited Literature.</p> <p>6. Other Tropisms and their Relationship to Gravitropism: Gladys I. Cassab.</p> <p>6.1 Introduction.</p> <p>6.2 Hydrotropism.</p> <p>6.2.1 Early studies of hydrotoprism.</p> <p>6.2.2 Genetic analysis of hydrotropism.</p> <p>6.2.3 Perception of moisture gradients and gravity stimuli by the root cap and the curvature response.</p> <p>6.2.4 ABA and the hydrotropic response.</p> <p>6.2.5 Future experiments.</p> <p>6.3 Electrotropism.</p> <p>6.4 Chemotropism.</p> <p>6.5 Thermotropism and oxytropism.</p> <p>6.6 Traumatropism.</p> <p>6.7 Overview.</p> <p>6.8 Acknowledgments.</p> <p>6.9 Literature cited.</p> <p>7. Single-Cell Gravitropism and Gravitaxis: Markus Braun and Ruth Hemmersbach.</p> <p>Introduction.</p> <p>7.1 Definitions of responses to environmental stimuli that optimize the ecological fitness of single-cell organisms.</p> <p>7.2 Occurrence and significance of gravitaxis in single-cell systems.</p> <p>7.3 Significance of gravitropism in single-cell systems.</p> <p>7.4 What makes a cell a biological gravity sensor?.</p> <p>7.5 Gravity susception - the initial physical step of gravity sensing.</p> <p>7.6 Susception in the statolith-based systems of Chara.</p> <p>7.7 Susception in the statolith-based system Loxodes.</p> <p>7.8 Susception in the protoplast-based systems of Euglena and Paramecium.</p> <p>7.9 Graviperception in the statolith-based systems of Chara.</p> <p>7.10 Graviperception in the statolith-based system Loxodes.</p> <p>7.11 Graviperception in the protoplast-based systems Paramecium and Euglena.</p> <p>7.12 Signal transduction pathways and graviresponse mechanisms in the statolith-based systems of Chara.</p> <p>7.13 Signal transduction pathways and graviresponse mechanisms in Euglena and Paramecium.</p> <p>7.14 Conclusions.</p> <p>7.15 Acknowledgements.</p> <p>7.18 Cited Literature.</p> <p>8. Space-Based Research on Plant Tropisms: Melanie J. Correll and John Z. Kiss.</p> <p>8.1 Introduction - the variety of plant movements.</p> <p>8.2 The microgravity environment.</p> <p>8.3 Ground-based studies: mitigating the effects of gravity.</p> <p>8.4 Gravitropism.</p> <p>8.4.1 Gravitropism: gravity perception.</p> <p>8.4.2 Gravitropism: signal transduction.</p> <p>8.4.3 Gravitropism: the curving response.</p> <p>8.5 Phototropism.</p> <p>8.6 Hydrotropism, autotropism and oxytropism.</p> <p>8.7 Studies of other plant movements in microgravity.</p> <p>8.8 Spaceflight hardware used to study tropisms.</p> <p>8.9 Future outlook and prospects.</p> <p>8.10 Cited Literature.</p> <p>.</p> <p>9. Plan(t)s for Space Exploration: Christopher S. Brown, Heike Winter Sederoff, Eric Davies, Robert J. Ferl, and Bratislav Stankovic.</p> <p>Introduction.</p> <p>9.1 Human missions to space.</p> <p>9.2 Life support.</p> <p>9.3 Genomics and space exploration.</p> <p>9.4 Nanotechnology.</p> <p>9.5 Sensors, biosensors and intelligent machines.</p> <p>9.6 Plan(t)s for space exploration.</p> <p>9.7 Imagine….</p> <p>9.8 Literature cited</p>
<b>Simon Gilroy</b>, Ph.D., is Associate Professor of Biology at Pennsylvania State University.<br /> <p><b>Patrick Masson</b>, Ph.D., is Professor of Genetics at the University of Wisconsin.</p>
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. <i>Plant Tropisms</i> will provide a comprehensive, yet integrated, volume of the current state of knowledge on the molecular and cell biological processes that govern plant tropisms.