Overexpression of CBL-Interacting Protein Kinases 23 Improves Tolerance to Low-Nitrogen Stress in Potato Plants

CBL-interacting protein kinases (CIPKs) play important regulatory roles in plant growth development and abiotic stress tolerance. However, the biological roles of these genes in response to low-nitrate (LN) stress in potato plants have not been determined. Here, we reported that StCIPK23 was expressed mainly in roots and leaves. StCIPK23 was located mainly in the cell membrane, nucleus, and cytoplasm. Further research suggested that, compared with wild-type (WT) plants, StCIPK23-overexpressing plants were taller and had significantly greater nitrate and ammonium nitrogen contents under LN stress. StCIPK23 overexpression can increase StAT, StNRT2.1, StNR, StGS1-3, and StGOGAT expression levels in StCIPK23 transgenic seedlings compared to those in WT plants under LN stress. The results of yeast two-hybrid and luciferase complementation imaging experiments suggested that StCIPK23 could interact with StCBL3. Real-time reverse transcription–PCR revealed the StCIPK23 expression level peaked at 6 h and the StCBL3 expression level peaked at 9 h in the roots under LN stress. In conclusion, we found that StCIPK23 and StCBL3 form a complex to regulate the expression of key genes in the nitrogen metabolism pathway to improve LN tolerance in potato plants.