Protein phosphorylation and dephosphorylation in environmental stress responses in plants

Abstract

This chapter discusses the biological roles of protein phosphorylation and dephosphorylation in environmental stress responses and explains the role of mitogen-activated protein (MAP) kinase in environmental stress signal transduction in higher plants. Protein kinases are essential for cellular activities. Genetic, biochemical, and pharmacological analyses have shown that protein kinases and protein phosphatases play important roles in environmental stress responses, including responsiveness to stress-induced phytohormones in plants. Protein phosphorylation/dephosphorylation has been shown to regulate diverse cellular processes in eukaryotes. Thousands of protein kinases have been reported and classified into several groups based on their structures, substrate specificities, and regulatory ligands. Recently, forward and reverse genetic approaches have led to the isolation of genes encoding protein kinases and protein phosphatases that play important roles in stress signaling in plants. The yeast two-hybrid system and the functional complementation tests with yeast mutants will be powerful tools for the isolation of regulators and substrates of the protein kinases and phosphatases.