Hydrogen peroxide mediates plant root cell response to nutrient deprivation

Abstract

Potassium (K⁺) is an essential nutrient required by plants in large quantities, but changes in soil concentrations may limit K⁺ acquisition by roots. It is not known how plant root cells sense or signal the changes that occur after the onset of K⁺ deficiency. Changes in the kinetics of Rb⁺ uptake in Arabidopsis roots occur within 6 h after K⁺ deprivation. Reactive oxygen species (ROS) and ethylene increased when the plants were deprived of K⁺. ROS accumulated in a discrete region of roots that has been shown to be active in K⁺ uptake and translocation. Suppression of an NADPH oxidase in Arabidopsis (rhd2), which is involved in ROS production, prevented the up-regulation of genes that are normally induced by K⁺ deficiency, but the induction of high-affinity K⁺ transport activity was unchanged. Application of H₂O₂ restored the expression of genes induced by K⁺ deficiency in rhd2 and was also sufficient to induce high-affinity K⁺ transport activity in roots grown under K⁺-sufficient conditions. ROS production is an early root response to K⁺ deficiency that modulates gene expression and physiological changes in the kinetics of K⁺ uptake.