Potassium homeostasis and signalling: from the whole plant to the subcellular level
Lars H. Wegner, Igor Pottosin, Ingo Drèyer, Sergey Shabala
Abstract
Abstract Potassium is an essential macronutrient required for plant growth and development. Over the recent decade, an important signalling role of K + has emerged. Here, we discuss some aspects of such signalling at the various levels of plant functional organisation. The topic covered include: (1) mechanisms of long-distant K + transport in the xylem and phloem and the molecular identity and regulation of K + loading and unloading into plant vasculature; (2) essentiality and physiological roles of K + cycling between shoots and roots; (3) plant sensing and signalling of low K + ; (4) maintenance of K + homeostasis at the cellular level; (5) stress-induced modulation of cytosolic K + as a signal in plant adaptive responses to hostile environment; (6) stress-specific K + “signatures” and mechanisms of their decoding by regulation of purine metabolism and H + -ATPase activity; (7) cytosolic K + loss as a metabolic switch and a regulator of autophagy; and (8) vacuolar K + transport and sensing.