Genomic & structural diversity and functional role of potassium (K) transport proteins in plants.

Potassium (K) is an essential macronutrient for plant growth and productivity. It is the most abundant cation in plants and is involved in various cellular processes. Variable K availability is sensed by plant roots, consequently K transport proteins are activated to optimize K uptake. In addition to K uptake and translocation these proteins are involved in other important physiological processes like transmembrane voltage regulation, polar auxin transport, maintenance of Na/K ratio and stomata movement during abiotic stress responses. K transport proteins display tremendous genomic and structural diversity in plants. Their key structural features, such as transmembrane domains, N-terminal domains, C-terminal domains and loops determine their ability of K uptake and transport and thus, provide functional diversity. Most K transporters are regulated at transcriptional and post-translational levels. Genetic manipulation of key K transporters/channels could be a prominent strategy for improving K utilization efficiency (KUE) in plants. This review discusses the genomic and structural diversity of various K transport proteins in plants. Also, an update on the function of K transport proteins and their regulatory mechanism in response to variable K availability, in improving KUE, biotic and abiotic stresses is provided.