19 - Molecular responses to extreme temperatures

Abstract

From the temperature change sensing to the temperature-responsive gene expression, with the signal transduction pathways in between, there are many levels at which cold and heat responses overlap. This chapter presents a general view of the current knowledge of how plants perceive and transduce the cold signal, and how low temperature response is regulated. It also discusses what has been reported on how plant responds to low and high temperatures, interact, and integrate, and on the potential common mechanisms and components that can mediate such an integration. Temperatures above the optimum are also highly stressful for plants, disturbing cellular homeostasis and leading to severe retardation in growth and development, and even death. Exposure to low temperature initiates numerous physiological perturbations; the first includes changes in cell membrane fluidity state and fatty acid composition. The content of sugar is also altered in plants in response to low temperature. The chapter also provides a general overview of how the cold signal is perceived, decoded, and transduced, and about the regulatory mechanisms controlling plant response to low temperature. Further, it is to be noted that some intermediates have been identified that seem to be particularly relevant and would constitute important nodes of integration between low- and high-temperature responses.