1;Preface;6 2;Contents;7 3;Ion Channels and Plant Stress: Past, Present, and Future;9 3.1;Introduction;10 3.2;Plasma Membrane K+ Channels in Guard Cells;12 3.2.1;Characterization of K+ Channel and Transporter cDNAs;13 3.3;Critical Roles of Plasma Membrane Anion Channels in Plant Stress Responses;14 3.4;Roles of Anion Channels in Stress Responses and Identification of Anion Channel Gene Families;15 3.5;Ca2+ Channels and Intracellular Ca2+ Elevations;16 3.6;Gene Candidates for Plasma Membrane Ca2+ Channels;17 3.7;Properties of Vacuolar Cation Channels;18 3.8;Sodium Transport Systems in Plants;18 3.9;Future Prospects;21 3.10;References;22 4;The Role of Ion Channels in Plant Salt Tolerance;31 4.1;Introduction;32 4.2;The Role of Ion Channels in Na+ Uptake: A Simple Model;33 4.2.1;Electrochemical Gradients and Fluxes;33 4.2.2;Fundamental Characteristics of Different Channel Types;35 4.2.3;Contribution of Different Channel Types to Na+ Uptake;37 4.3;The Role of Ion-Channels in Salt Tolerance: Experimental Evidence;43 4.3.1;Ion Channels and Salt Tolerance in Crops;43 4.3.2;Ion Channels and Salt Tolerance in Arabidopsis thaliana;44 4.3.3;Ion Channels and Salt Tolerancesalt tolerance in Halophytic Higher Plants;45 4.3.4;Ion Channels and Salt Tolerance in Charophytescharophytes;47 4.4;Summary and Conclusions;50 4.5;References;50 5;Cation Channels and the Uptake of Radiocaesium by Plants;55 5.1;Background;56 5.2;Historical Studies;57 5.3;Caesium Transport Proteins in Root Cells;58 5.4;Molecular Mechanisms for Cs Uptake by Roots of Non-Mycorrhizal Plants;63 5.4.1;K-Replete Plants;63 5.4.2;K-Starved Plants;65 5.4.3;Differences between Plant Species;66 5.5;Molecular Mechanisms for Cs Uptake by Roots of Mycorrhizal Plants;67 5.6;Prospects for the Generation of Safer Crops;68 5.7;References;69 6;Ion Channels in Plant Development;76 6.1;Ion Channels in Plant Development;77 6.1.1;Molecular Identification of K+- and Anion Channels in Plant Development;77 6.1.2;Molecular Identification of Mechanosensitive Channels;78 6.1.3;Glutamate Receptor-Like Channels and Cyclic-Nucleotide Gated Channels;79 6.2;Ion Channels Acting in Concert;82 6.2.1;Ion Channels in Root Hair Development;82 6.2.2;Ion Channels in Pollen Tube Growth;84 6.2.3;Ion Channels in Algal Development;86 6.2.4;Ion Channels in Nodule Development;86 6.3;Conclusions;87 6.4;References;88 7;Potassium and Potassium-Permeable Channels in Plant Salt Tolerance;94 7.1;Introduction;95 7.1.1;Salinity as an Issue;95 7.1.2;Physiological Constraints Imposed by Salinity;96 7.2;Potassium Homeostasis in Plants;96 7.2.1;Potassium Essentiality and Functions in Plants;96 7.2.2;Tissue- and Organelle-Specific Potassium Compartmentation;97 7.2.3;Major Potassium Transport Systems: A Brief Overview;98 7.2.4;Potassium and Potassium-Permeable Channels;98 7.3;Regulation of K+ Channel Activity Under Saline Conditions;99 7.3.1;K+ Channels and ``Osmotic´´ and ``Ionic´´ Components of Salt Stress;99 7.3.2;GORK and AKT Channels as Downstream Targets of Salinity Effects;101 7.3.3;Voltage Gating and the Role of H+-ATPases;102 7.3.4;Maintaining the Optimal Cytosolic K+/Na+ Ratio;102 7.3.5;Long-term Salinity Exposure and Regulation of K+ Transport;103 7.3.6;Tonoplast (Vacuolar) Channels;105 7.3.6.1;Properties of K+-Permeable Vacuolar Channels;105 7.3.6.2;Vacuolar Channels and Cytosolic K+ Homeostasis;106 7.3.6.3;Regulation of Vacuolar Channel Activity Under Saline Conditions;106 7.3.7;Chloroplasts and Mitochondria;108 7.3.7.1;Salinity and Photosynthesis;108 7.3.7.2;Photosynthetic Activity, Stromal pH, and Membrane Transport in Chloroplasts;108 7.3.7.3;Role of the Envelope K+(Na+)/H+ Antiport in Salt Tolerance;109 7.3.7.4;Mitochondrial Channels;109 7.4;Concluding Remarks and Future Prospects;110 7.5;References;111 8;Regulation of Ion Channels by the Calcium Signaling Network in Plant Cells;118 8.1;Introduction;118 8.2;CDPKs, Plant Calcium ``Sensor-Responders´´ that Regulate Ion Channels;120 8.2.1;Structural Diversity and Regula