Modulation of potassium transport to increase abiotic stress tolerance in plants.

Potassium is the major cation responsible for the maintenance of the correct ionic environment in plant cells. Stable potassium homeostasis is indispensable for virtually all cellular functions, and, concomitantly, viability. Plants must cope with environmental changes, such as salt or drought, which can alter ionic homeostasis. Potassium fluxes are required to regulate the essential process of transpiration, so a constraint in potassium transport may also affect the plant's response to heat, cold or oxidative stress. Sequencing data and functional analyses have defined the potassium channels and transporters present in the genomes of different species, so we know most of the proteins directly participating in potassium homeostasis. The still unanswered questions are how these proteins are regulated and the potential cross-talk with other signaling pathways controlling growth, development and stress responses. As we gain knowledge regarding the molecular mechanisms underlying potassium homeostasis regulation in plants, we can take advantage of this information to increase the efficiency of potassium transport and generate plants with enhanced tolerance to abiotic stress through genetic engineering or new breeding techniques. Here, we review the published information on how modifying genes related to potassium homeostasis in plants affects abiotic stress tolerance at the whole plant level.