Influence of Nutritional Environment on Plant Potassium and Organic Carbon Fractionation in Arabidopsis thaliana Plants

Abstract

Potassium is integral to many biological processes in plants. Without sufficient K content, stomata cannot open, gas exchange is halted, and photosynthesis cannot proceed, resulting in chlorosis and premature death. Potassium availability in the environment, however, varies significantly across the globe and is quickly depleted on heavily farmed soils. In this paper, we apply stable isotope geochemistry to hydroponically grown Arabidopsis thaliana plants to elucidate the relationship between environmental K availability, influx, carbon fixation, and plant growth. We find that two transport mechanisms are responsible for plant K (high affinity vs low affinity), distinguishable by their distinctive δ41K isotopic signatures. Plants grown at 0.10 mM environmental K exhibited δ41K values in line with the high affinity transport system employed under stressed conditions without showing significant reductions in plant K acquisition relative to plants grown in more replete potassium environments. If species variation can be parameterized, these results suggest that K efficient crop growth can be achieved by amending soil K to optimize the high affinity transport system.