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.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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