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 Ca2+ sensors with diverse functions in nitrogen and drought signaling pathways. However, which and how CPKs involve in the crosstalk between drought stress and nitrogen transportation remains largely unknown. Here we identified the drought tolerant function of Arabidopsis CPK6 under high nitrogen condition. The CPK6 expression is induced by the treatments of ABA and drought. The mutant cpk6 is insensitive to the ABA treatment, but sensitive to drought only under high nitrogen condition. CPK6 interacts with and phosphorylates the Thr571 in NRT1.1 protein, and thus represses its NO3- transporting activity under drought stress. Taken together, we showed the evidences that CPK6 regulates Arabidopsis drought tolerance through the phosphorylation of NRT1.1, and that enriches the knowledge of nitrogen uptake in plants during drought stress.