Na+ efflux

Roots of intact seedlings were immersed for 1 h in growth solution supplemented with ²⁴Na⁺, before seedlings were removed and secured to the inside of glass efflux funnels (Coskun et al., 2014). Roots were then eluted of radioactivity with successive 13 ml aliquots of non-radioactive growth solution every 1.5 min, for a total of 39 min of elution. A subset of efflux experiments was conducted with the final 12 eluates (from the 22.5 min point onwards in the elution protocol) being supplemented with 1 mM KCN and 1 mM salicylhydroxamic acid (SHAM), standard inhibitors of the cytochrome c oxidase and alternative oxidase respiratory pathways, respectively. Unidirectional influx and efflux were determined according to the method of Siddiqi et al., 1991.