Amiloride reduces sodium transport and accumulation in the succulent xerophyte Zygophyllum xanthoxylum under salt conditions.

To investigate the effects of amiloride, which is an inhibitor of Na(+)/H(+) antiporter (NHX), on Na(+) accumulation and transport at the whole plant level, in this study, 3-week-old Zygophyllum xanthoxylum plants were exposed to 25, 50 and 100 mM NaCl with or without 0.5 mM amiloride. After 72 h of treatment, dry weight, tissue water content, Na(+) and K(+) concentrations, and transcript levels of ZxNHX were determined. The results indicated that, under salt conditions, leaf Na(+) concentration, total Na(+) quantity and root net Na(+) uptake rate in plants treated with amiloride are significantly lower than those in control plants. Amiloride remarkably increased Na(+) proportion in stem and decreased Na(+) proportion in leaf of Z. xanthoxylum. Furthermore, our results showed that the transcript levels of ZxNHX are down-regulated by amiloride. It is clear that the inhibition of vacuolar Na(+)/H(+) antiporter by amiloride could disrupt Na(+) accumulation of leaf, and reduce Na(+) uptake by root and Na(+) transport from stem to leaf, thus resulting in the growth inhibition of Z. xanthoxylum exposed to salt.