¹³⁴Cs Uptake and Growth at Various Cs⁺ and K⁺ Levels in Arabidopsis AtKUP7 Mutants

Radiocaesium is a pollutant with a high risk for the environment, agricultural production, and human health. It is mobile in ecosystems and can be taken up by plants via potassium transporters. In this study, we focused on the role of potassium transporter AtKUP7 of the KT/HAK/KUP family in Cs⁺ and K⁺ uptake by plants and in plant tolerance to caesium toxicity. We detected that Arabidopsiskup7 mutant accumulates significantly lower amounts of ¹³⁴Cs in the root (86%) and in the shoot (69%) compared to the wild-type. On the other hand ability of the mutant to grow on media with toxic (100 and 200 µM) concentrations of Cs⁺ was not changed; moreover its growth was not impaired on low K⁺. We further investigated another mutant line in AtKUP7 and found that the growth phenotype of the kup7 mutants in K⁺ deficient conditions is much milder than previously published. Also, their accumulation of K⁺ in shoots is hindered only by severe potassium shortage.