Hydroxyl radical-activated potassium channels are involved in stress-induced apoptosis

Reactive oxygen species (ROS) are important toxic and regulatory substances in plants, and are induced by a series of biotic and abiotic stresses, hormones, development and gravity signals, and loss of mineral metabolism. At present, many reactive oxygen sensing systems including MAPK kinases, transcription factors and the like have been discovered. In addition, plasma membrane ion channels may also be involved in plant reactive oxygen species sensing and reactive oxygen species mediated regulation. The important role of plasma membrane ion channels of reactive oxygen species in key physiological functions of animals has been well established, but in plants, the nature and function of such ion channels, especially hydroxyl radical (HR) -activated K+ channels, are unclear.

On April 7, 2010, British scientist Demidchik et al used Arabidopsis thaliana (WT) and K+ outflow channel gene deletion mutant ( gork1-1 ) as the research object, using non- invasive micro-test technology, electronic paramagnetic Resonance (EPR), patch clamp, and cell imaging methods were used to study the K+ flow rate, oxygen free radicals, membrane potential, and apoptotic cell morphology of Arabidopsis roots and their protoplasts under different treatment conditions. The study found that both HR and stress can cause significant K+ efflux in the roots of Arabidopsis seedlings, but the outflow in the mutants is significantly weaker. NaCl induces HR production in the roots and activates the K+ channel. The wild type Arabidopsis root cells treated with the mutant gork1-1 and K+ channel inhibitor or HR scavenger had slower apoptosis. It follows that HR-activated K+ channels in plants are also involved in apoptosis.

This study presents a new perspective on ROS regulation of plant cation transport and illustrates the physiological role of HR-activated K+ channels in plants.