Plant protein phosphatases 2C: from genomic diversity to functional multiplicity and importance in stress management

Protein phosphatases (PPs) counteract kinases in reversible phosphorylation events during numerous signal transduction pathways in eukaryotes. Type 2C PPs (PP2Cs) represent the major group of PPs in plants, and recent discovery of novel abscisic acid (ABA) receptors (ABARs) has placed the PP2Cs at the center stage of the major signaling pathway regulating plant responses to stresses and plant development. Several studies have provided deep insight into vital roles of the PP2Cs in various plant processes. Global analyses of the PP2C gene family in model plants have contributed to our understanding of their genomic diversity and conservation, across plant species. In this review, we discuss the genomic and structural accounts of PP2Cs in plants. Recent advancements in their interaction paradigm with ABARs and sucrose nonfermenting related kinases 2 (SnRK2s) in ABA signaling are also highlighted. In addition, expression analyses and important roles of PP2Cs in the regulation of biotic and abiotic stress responses, potassium (K+) deficiency signaling, plant immunity and development are elaborated. Knowledge of functional roles of specific PP2Cs could be exploited for the genetic manipulation of crop plants. Genetic engineering using PP2C genes could provide great impetus in the agricultural biotechnology sector in terms of imparting desired traits, including a higher degree of stress tolerance and productivity without a yield penalty.