Water-deficit stress signal transduction pathways in plants: From sensing to response

Abstract

As sessile organisms plants have to cope with changing environmental conditions. Drought and salinity, which causes water-deficit in plant cells, are common adverse factors that limit plant growth and productivity. Understanding the mechanisms by which plants perceive environmental signals and transmit them to cellular machinery to activate adaptive responses is of great importance to biology and to rational engineering of crop plants. This chapter reviews the signal transduction mechanisms that activate water-deficit stress responses and the regulation of transcription factors that control the expression of stress-responsive genes. The general components of stress signal transduction pathway for drought and salt stress are considered. Signal perception, receptor-coupled phosphorelay, phosphoinositol-induced Ca2+ changes, Ca2+-coupled phosphoprotein cascades, mitogen-activated protein kinase cascade and transcriptional activation of stress responsive genes are the main signal transduction steps addressed. Abscisic acid (ABA) plays a pivotal role in stress responses in plants. Therefore, the hormone implications are also reviewed. The transcription factors responsible for reprogramming gene expression in response to stress are described. Finally, the physiological and biochemical responses that lead to plant tolerance to water-deficit stress are addressed.