Characterization of Sorghum Potassium Transport Genes under Abiotic Stress

Potassium (K+) is a vital macronutrient in Sorghum bicolor and other plants, playing a fundamental part in processes such as ion homeostasis, plant growth, development, transport, and signaling. It is of paramount importance for regulating plants exposed to abiotic stresses. Since plants can only absorb potassium in its ionic form, which typically is below the needed concentration near the roots, they rely on two mechanisms for uptake: a low affinity system that functions when extracellular K+ concentration is high (> 200 μM to mM) and a high affinity system that functions when extracellular concentration is low (20 μM Rb+) (Gierth et al., 2005). In an effort to understand the sorghum K+ transport gene family, Kumar and colleagues from Vignan’s Foundation for Science, Technology & Research, Florida A&M University, ICRISAT, Florida State University and the National Institute of Nutrition (India) performed homology and phylogenetic analyses starting from a set of 49 known K+ encoding rice genes. The sorghum gene family was enriched by functional analyses and expression profiling. Of the 47 K+ transport gene homologs that have been identified in Sorghum bicolor, 33 were K+ transporters and 14 were K+ channels. The researchers identified 9 genes on chromosome 2 associated with K+ transporters. Analysis of expression data revealed that expression of certain genes was higher during the milk (SbHAK17, SbHAK11, SbHAK18, and SbHAK7), flowering (SbHAK18, SbHAK10), and tillering stages (23 additional genes). This indicates that K+ transport genes play an integral part in the growth and development of the plant. In addition, differential expression was also observed in root, stem, and leaf tissues and under varying abiotic stresses such as salt, drought, heat, and cold.

SorghumBase example:

Figure1: SORBI_3002G220600 (Sb02g026170, Sobic.002G220600) or SbHAK17 is probably similar to potassium transporter 17. Shown in the image is a gene expression profile highlighting with a study with highest expression (27 TPM) in pistil and anthers.


Anil Kumar S, Hima Kumari P, Nagaraju M, Sudhakar Reddy P, Durga Dheeraj T, Mack A, Katam R, Kavi Kishor PB. Genome-wide identification and multiple abiotic stress transcript profiling of potassium transport gene homologs in Sorghum bicolor. Front Plant Sci. 2022 Sep 2;13:965530. PMID: 36119582. DOI: 10.3389/fpls.2022.965530. Read more

Gierth M, Mäser P, Schroeder JI. The potassium transporter AtHAK5 functions in K(+) deprivation-induced high-affinity K(+) uptake and AKT1 K(+) channel contribution to K(+) uptake kinetics in Arabidopsis roots. Plant Physiol. 2005 Mar;137(3):1105-14. PMID: 15734909. DOI: 10.1104/pp.104.057216.