Functional Roles of Plant Protein Kinases in Signal Transduction Pathways during Abiotic and Biotic Stress

A process whereby a cell communicates and responses to external stimuli to alter plant growth, development, physiology and morphology is known as signal transduction. The integration of various signaling information and activities is important to generate a final response to the external stimuli. Protein kinases of protein phosphorylation are implicated in different signal transduction pathways in response to abiotic and biotic stress. Plants are always subjected to various ranges of abiotic and biotic stress. Protein phosphorylation is a post-translational modification process in which an amino acid residue of a protein is covalently modified by addition of a phosphate group involving an enzyme known as protein kinase. Protein kinases are among the most common cellular regulatory components of signal transduction in plants. Many studies demonstrate the prominent roles of protein kinases in the regulation of cell differentiation, growth and development of plant system. Plant growth is greatly affected by abiotic factors including low temperature, high salinity, osmotic stress, drought and biotic factors such as wounding as a result of invasion of various pathogens that eventually triggers the activation of plant defense system. Thus, this paper summarizes plant regulatory mechanisms of protein kinases via signal transduction process during abiotic and biotic stress. This paper also assesses the functional roles of protein kinases of phosphorylation in plant signaling pathways in response to abiotic and biotic stress. In a nutshell, in-depth knowledge about the roles of protein kinases is a prerequisite for the plant growth and development with their ability against various hostile environments.