Rice Na + absorption mediated by OsHKT2;1 affected Cs + translocation from root to shoot under low K + environments.

¹³⁷ Cs diffused into the environment due to a nuclear power plant accident has caused serious problems for safe crop production. In plants, Cs ⁺ is similar in its ionic form to K ⁺ . Cs ⁺ is absorbed and transported mainly by the K ⁺ transport mechanism. However, the full picture of the genes contributing to Cs ⁺ transport and the transport mechanism of rice is still unclear. This study focused on OsHKT2;1, a candidate Cs ⁺ transporter under low K ⁺ conditions. To verify the ability of OsHKT2;1 to transport Cs ⁺ , the OsHKT2;1 mutant ( hkt2;1 ) was grown in a ¹³⁷ Cs-contaminated paddy field in Fukushima. The ¹³⁷ Cs concentration in hkt2;1 aboveground was higher than in the wild type (WT), and the K concentration in these samples did not change between WT and hkt2;1 , whereas the Na concentration was lower in hkt2;1 . Uptake experiments with radioactive tracers ( ²² Na ⁺ , ⁴³ K ⁺ , and ¹³⁷ Cs ⁺ ) in hydroponic systems with different elemental compositions showed a negative correlation between Na ⁺ and Cs ⁺ accumulation in rice shoot cultivated under low K ⁺ conditions. These results indicated that OsHKT2;1 does not directly contribute to Cs ⁺ uptake but is an important factor in regulating Cs ⁺ translocation by controlling Na ⁺ accumulation. This indicates the possibility of controlling rice Cs content by regulating the Na ⁺ environment during cultivation.
Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision.
(Copyright © 2024 Kanno, Fujimura, Takahashi, Li, Shinano, Nakamura, Leonhardt and Furukawa.)