This book aims to provide a range of perspectives on an area that is very topical at present in plant biology: the role of ion channels in plant stress responses. Functions of cation and anion channels in the sensing and encoding of major biotic and abiotic stimuli, stress signal transduction and metabolism adjustment are examined at the cellular and molecular levels. Particular emphases of the book are on new insights into plant Ca2+ signaling, salinity tolerance mechanisms, cyclic nucleotide gated channels and the regulation of stress reactions among oxygen-derived species.