CPK signaling orchestrates the plant nitrate regulatory network

Nitrate is the limiting nitrogen nutrient enabling photosynthetic plants to support the conversion of inorganic elements to organic biomass, which sustains all lives. Plants evolved multifaceted nitrate responses to modulate global gene expression, metabolism and developmental programs. However, primary nitrate signaling mechanisms remained elusive. Using an ultrasensitive Ca2+ biosensor, unique nitrate-induced Ca2+ signaling was illuminated in Arabidopsis cells and plants. Integrative functional genomic screens, chemical genetics, genome-wide transcript sequencing, and analyses of nitrate-associated traits uncovered the surprising roles of Ca2+ sensor protein kinases (CPKs) in orchestrating diverse primary and long-term nitrate responses. Nitrate specifies CPK signaling to reprogram transcriptome and govern N-assimilation, metabolism, transport, hormones, shoot growth, and root system architecture. CPKs may be targeted to enhance nitrogen-use-efficiency, reduce fertilizer demands, and alleviate ecosystem pollution. genome-wide survey of the wild type and icpk mutant in response to nitrate