Temperature sensing by plants: a review and hypothesis

Abstract. The different effects which fast versus slow cooling have on such fundamental plant processes as ion transport, protoplasmic streaming, phloem translocation, growth, cell motility, water absorption and membrane potential are reviewed. When plant cells are rapidly cooled to non-injurious temperatures, many of the physiological ramifications of rapid-cooling stimulation are only transiently observed. It is proposed that these transient rapid-cooling-induced responses, sometimes elicited by temperature drops of only a few degrees centigrade, are manifestations of temperature sensing. The hypothesis is advanced that graded potentials, produced in response to rapidly falling temperature, are associated with graded increases in cytosolic free calcium. These transient increases in cytosolic free calcium give rise to many of the physiological effects elicited by rapid cooling. Other effects, however, such as those associated with alterations in membrane composition, gene expression and post-translational modifications of proteins, may persist longer. The questions of the possible physiological advantage of temperature sensing, and its implications for the study of chilling injury, are discussed.