ATP binding cassette proteins ABCG37 and ABCG33 function as potassium-independent cesium uptake carriers in Arabidopsis roots

Radiocesium accumulated in the soil by nuclear accidents is a major environmental concern. The transport process of cesium (Cs+) tightly linked to indispensable plant nutrient potassium (K+) as they both belong group I alkali metals with similar chemical properties. Most transporters that had been characterized date Cs+ are directly or indirectly K+. Using combinatorial approach physiology, genetics, cell biology, and root uptake assay, here we identified two ATP-binding cassette (ABC) proteins, ABCG37 ABCG33, facilitators influx. A gain-of-function mutant (abcg37-1) showed increased sensitivity Cs+-induced growth inhibition, while double knockout ABCG33 (abcg33-1abcg37-2) resistance, whereas single loss-of-function mutants did not show any alteration response. In planta short-term radioactive Cs+-uptake assay along assays heterologous system confirmed carriers. Potassium response content were unaffected double-mutant background yeast cells lacking potassium-uptake carriers transformed failed grow absence K+, confirming independent Collectively, this work ABC proteins new Cs+-influx act redundantly K+-uptake pathway.