A tonoplast-localized TPK-type K transporter (TPKa) regulates potassium accumulation in tobacco.

Potassium ion (K) is one of the most essential nutrients for the growth and development of tobacco (Nicotiana tabacum L.), however, the molecular regulation of K concentration in tobacco remains unclear. In this study, a two-pore K (TPK) channel gene NtTPKa was cloned from tobacco, and NtTPKa protein contains the unique K selection motif GYGD and its transmembrane region primarily locates in the tonoplast membrane. The expression of NtTPKa gene was significantly increased under low-potassium stress conditions. The concentrations of K in tobacco were significantly increased in the NtTPKa RNA interference lines and CRISPR/Cas9 knockout mutants. In addition, the transport of K by NtTPKa was validated using patch clamp technique, and the results showed that NtTPKa channel protein exclusively transported K in a concentration-dependent manner. Together, our results strongly suggested that NtTPKa is a key gene in maintaining K homeostasis in tobacco, and it could provide a new genetic resource for increasing the concentration of K in tobacco.