RT Journal Article SR Electronic T1 A Grain of Salt JF bioRxiv FD Cold Spring Harbor Laboratory SP 2020.01.23.916742 DO 10.1101/2020.01.23.916742 A1 Kelly Houston A1 Jiaen Qiu A1 Stefanie Wege A1 Maria Hrmova A1 Helena Oakey A1 Yue Qu A1 Pauline Smith A1 Apriadi Situmorang A1 Malcolm Macaulay A1 Paulina Flis A1 Micha Bayer A1 Stuart Roy A1 Claire Halpin A1 Joanne Russell A1 Caitlin Byrt A1 Matt Gilliham A1 David E. Salt A1 Robbie Waugh YR 2020 UL http://biorxiv.org/content/early/2020/01/23/2020.01.23.916742.abstract AB We quantified grain sodium (Na+) content across a barley GWAS panel grown under optimal conditions. We identified a strong association with a region containing two low and one high Na+ accumulating haplotypes of a Class 1 HIGH-AFFINITY POTASSIUM TRANSPORTER (HKT1;5) known to be involved in regulating plant Na+ homeostasis. The haplotypes exhibited an average 1.8-fold difference in grain Na+ content. We show that an L189P substitution disrupts Na+ transport in the high Na+ lines, disturbs the plasma membrane localisation typical of HKT1;5 and induces a conformational change in the protein predicted to compromise function. Under NaCl stress, lines containing P189 accumulate high levels of Na+, but show no significant difference in biomass. P189 increases in frequency from wild-species to elite cultivars leading us to speculate that the compromised haplotype is undergoing directional selection possibly due to the value of Na+ as a functional nutrient in non-saline environments.