A Grain of Salt

Houston, K.; Qiu, J.; Wege, S.; Hmrova, M.; Oakey, H.; Qu, Y.; Smith, P.; Situmorang, A.; Macaulay, M.; Flis, P.; Bayer, M.; Roy, S.; Halpin, C.; Russell, J.; Byrt, C.; Gilliham, M. J.; Salt, D. E.; Waugh, R.

doi:10.1101/2020.01.23.916742

bioRxiv · 10.1101/2020.01.23.916742

A Grain of Salt

Houston, K.·Qiu, J.·Wege, S.·Hmrova, M.·Oakey, H.·Qu, Y.·Smith, P.·Situmorang, A.·Macaulay, M.·Flis, P.·Bayer, M.·Roy, S.·Halpin, C.·Russell, J.·Byrt, C.·Gilliham, M. J.·Salt, D. E.·Waugh, R.

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Abstract

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.

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Houston, K., Qiu, J., Wege, S., Hmrova, M., Oakey, H., Qu, Y., Smith, P., Situmorang, A., Macaulay, M., Flis, P., Bayer, M., Roy, S., Halpin, C., Russell, J., Byrt, C., Gilliham, M. J., Salt, D. E., Waugh, R.. 2020-01-23. A Grain of Salt. https://doi.org/10.1101/2020.01.23.916742

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