A Role for the AKT1 Potassium Channel in Plant Nutrition

TLDR

Potassium is essential for plant osmotic balance and charge transport, yet the mechanisms of root uptake remain poorly defined. The study aimed to determine the role of potassium channels in planta by performing a reverse genetic screen that identified an Arabidopsis thaliana mutant lacking the AKT1 channel gene. The reverse genetic screen identified an Arabidopsis thaliana mutant with a disrupted AKT1 channel gene. The AKT1‑deficient mutant lacked inward‑rectifying potassium channels, exhibited reduced potassium uptake, grew poorly on low‑potassium media, and membrane potential data indicate that AKT1 mediates uptake from solutions as low as 10 µM potassium.

Abstract

In plants, potassium serves an essential role as an osmoticum and charge carrier. Its uptake by roots occurs by poorly defined mechanisms. To determine the role of potassium channels in planta, we performed a reverse genetic screen and identified an Arabidopsis thaliana mutant in which the AKT1 channel gene was disrupted. Roots of this mutant lacked inward-rectifying potassium channels and displayed reduced potassium (rubidium-86) uptake. Compared with wild type, mutant plants grew poorly on media with a potassium concentration of 100 micromolar or less. These results and membrane potential measurements suggest that the AKT1 channel mediates potassium uptake from solutions that contain as little as 10 micromolar potassium.