Arabidopsis CPK6 regulates drought tolerance under high nitrogen by the phosphorylation of NRT1.1.

Nitrogen is an essential macronutrient for plant growth and development, and its availability to some extent is regulated by drought stress. Calcium-dependent protein kinases (CPKs) are a unique family of Ca 2+ sensors with diverse functions in nitrogen uptake and drought tolerance signaling pathways. However, how CPKs involve in the crosstalk between drought stress and nitrogen transportation remains largely unknown. Here we identify the drought tolerant function of Arabidopsis CPK6 under high nitrogen condition. CPK6 expression is induced by the treatments of ABA and drought. The mutant cpk6 is insensitive to the ABA treatment and low nitrogen, but sensitive to drought only under high nitrogen condition. CPK6 interacts with NRT1.1 protein and phosphorylates the Thr447 residue, which then represses the NO3  - transporting activity of Arabidopsis under HN and drought stress. Taken together, we showed the evidences that CPK6 regulates Arabidopsis drought tolerance through changing NRT1.1 phosphorylation states, and that enriches the knowledge of nitrogen uptake in plants during drought stress.