Role of calcium-mediated CBL-CIPK network in plant mineral nutrition and abiotic stress

Abstract

In plants like other organisms, nutrition plays a vital role in biological processes such as growth, development and reproduction. Extensive studies done in the field of plant nutrition signalling using Arabidopsis thaliana as a model system have unravelled the calcium-mediated regulation of various ion transporters and channels involved in mineral nutrient acquisition and assimilation. Unlike animals, the immobile nature of plants makes them more vulnerable to the unavoidable environmental conditions in which they grow and are exposed to numerous biotic as well as abiotic stresses. Nutrition deprivation severely affects soil productivity, crop yield, and quality and stress resistance. So, a rapid and efficient signalling mechanism in response to disturbances in nutrient levels is crucial for the survival of organisms from bacteria to humans. Plants have, therefore, evolved a host of molecular pathways that can sense nutrient concentrations, both intracellular and extracellular, and quickly regulate gene expression and protein modifications to respond to any such changes. Ion channels and transporters present in the plasma membrane aid in acquisition of these nutrients. Nutrient deprivation acts as a trigger for the activation of calcium-mediated CBL-CIPK complex signalling pathways that integrate adaptive responses in plants. Several members of CBL-CIPK family such as CBL1, CBL9, CIPK6, CIPK8, CIPK16 and CIPK23 work in combination in multiple nutrient-sensing pathways to confer specific responses during uptake and transport of minerals especially nitrate and potassium. The regulatory circuit of these ion channels and transporters involves multiple post-translational modifications like phosphorylation by CBL-CIPK complex, which modulates the nutrient uptake properties in response to changes in soil nutrient concentration. This chapter concisely discusses the imperative role of newly identified CBL-CIPK members as crucial components of potassium- and nitrate-sensing mechanisms during nutrition uptake, allocation and signalling.