Barley sodium content is regulated by natural variants of the Na+ transporter HvHKT1;5
Kelly Houston, Jiaen Qiu, Stefanie Wege, Mária Hrmová, Helena Oakey, Yue Qu, Pauline Smith, Apriadi Situmorang, Malcolm Macaulay, Paulina Flis, Micha Bayer, Stuart J. Roy, Claire Halpin, Joanne Russell, Miriam Schreiber, Caitlin S. Byrt, Matthew Gilliham, David E. Salt, Robbie Waugh
Abstract
Abstract During plant growth, sodium (Na + ) in the soil is transported via the xylem from the root to the shoot. While excess Na + is toxic to most plants, non-toxic concentrations have been shown to improve crop yields under certain conditions, such as when soil K + is low. We quantified grain Na + across a barley genome-wide association study panel grown under non-saline conditions and identified variants of a Class 1 HIGH-AFFINITY-POTASSIUM-TRANSPORTER ( HvHKT1;5 )-encoding gene responsible for Na + content variation under these conditions. A leucine to proline substitution at position 189 (L189P) in HvHKT1;5 disturbs its characteristic plasma membrane localisation and disrupts Na + transport. Under low and moderate soil Na + , genotypes containing HvHKT1:5 P189 accumulate high concentrations of Na + but exhibit no evidence of toxicity. As the frequency of HvHKT1:5 P189 increases significantly in cultivated European germplasm, we cautiously speculate that this non-functional variant may enhance yield potential in non-saline environments, possibly by offsetting limitations of low available K + .